Power plant technology (lecture notes)

1

POWER PLANT TECHNOLOGY

BY. ENGR YURI G. MELLIZA

Table of Contents

Introduction ..................................................................................................................................................................... 7

Introduction to Thermodynamics ..................................................................................................................................... 8

Law of Conservation of Mass ........................................................................................................................................... 8

Continuity Equation ......................................................................................................................................................... 8

Forms of Energy ............................................................................................................................................................... 9

Internal Energy: ........................................................................................................................................................... 9

Flow Energy or Flow Work:........................................................................................................................................... 9

Heat: ............................................................................................................................................................................ 9

Work: ........................................................................................................................................................................... 9

Kinetic Energy: ........................................................................................................................................................... 10

Potential Energy: ........................................................................................................................................................ 10

Zeroth Law of Thermodynamics: .................................................................................................................................... 10

Specific Heat or Heat Capacity: ................................................................................................................................... 10

Sensible Heat: ............................................................................................................................................................ 11

Heat of Transformation .............................................................................................................................................. 11

A. Latent Heat of Vaporization: ........................................................................................................................... 11

Phase Change ................................................................................................................................................................ 11

Ideal or Perfect Gas ........................................................................................................................................................ 12

2

IDEAL GAS MIXTURE ...................................................................................................................................................... 14

1. Total moles of a mixture ......................................................................................................................................... 14

2. Mole Fraction ......................................................................................................................................................... 14

3. Total mass of a mixture .......................................................................................................................................... 14

4. Mass Fraction ......................................................................................................................................................... 14

5. Equation of State .................................................................................................................................................... 14

6. Amagat's Law: ........................................................................................................................................................ 15

7. Dalton's Law: .......................................................................................................................................................... 15

8. Molecular Weight of a Mixture ............................................................................................................................... 16

9. Gas Constant of a mixture ...................................................................................................................................... 16

10. Specific Heats of a mixture ................................................................................................................................... 16

11. Gravimetric and Volumetric Analysis: ................................................................................................................... 16

Law of conservation of Energy (The First Law of Thermodynamics): ............................................................................... 17

Application of the Law of Conservation of Energy....................................................................................................... 17

B. Open System ...................................................................................................................................................... 17

Processes of Fluids ......................................................................................................................................................... 18

1. Isobaric Process: ................................................................................................................................................. 18

2. Isometric Process: .............................................................................................................................................. 19

3. Isothermal Process: ............................................................................................................................................ 20

4. Isentropic Process: ............................................................................................................................................. 21

5. Polytropic Process: ............................................................................................................................................. 22

6. Throttling Process:.............................................................................................................................................. 23

3

Properties of Pure Substance: ........................................................................................................................................ 23

Terms and Definition .............................................................................................................................................. 25

Throttling Calorimeter ................................................................................................................................................... 26

Fuels and Combustion .................................................................................................................................................... 29

Combustion Chemistry ............................................................................................................................................... 30

Combustion of Combustible elements with Air: .......................................................................................................... 31

Theoretical Air: .......................................................................................................................................................... 32

Excess Air: .................................................................................................................................................................. 32

Hydrocarbon Fuel: ..................................................................................................................................................... 32

COMBUSTION OF HYDROCARBON FUEL(CnHm) ......................................................................................................... 32

COMBUSTION OF SOLID FUELS ................................................................................................................................... 33

DEW POINT TEMPERATURE .................................................................................................................................... 33

ULTIMATE ANALYSIS ............................................................................................................................................... 33

PROXIMATE ANALYSIS ............................................................................................................................................ 33

ORSAT ANALYSIS .................................................................................................................................................... 33

MASS FLOW RATE OF FLUE GAS ............................................................................................................................. 33

a) Without considering Ash loss: ............................................................................................................................. 33

b) Considering Ash loss ........................................................................................................................................... 34

MOLECULAR WEIGHT OF PRODUCTS ...................................................................................................................... 34

GAS CONSTANT OF PRODUCTS ............................................................................................................................... 34

SPECIFIC HEATS OF PRODUCTS ............................................................................................................................... 34

PARTIAL PRESSURE OF COMPONENTS .................................................................................................................... 35

4

HEATING VALUE ............................................................................................................................................................. 38

For Liquid Fuels ...................................................................................................................................................... 38

For Gasoline ........................................................................................................................................................... 38

For Fuel Oils ........................................................................................................................................................... 38

For Fuel Oils (From Bureau of Standard Formula) ................................................................................................... 38

Properties of Fuels and Lubricants ................................................................................................................................. 39

Cycle .............................................................................................................................................................................. 40

Steam Power Plant Cycle................................................................................................................................................ 40

Rankine Cycle ............................................................................................................................................................. 40

Reheat Cycle Steam Power Plant: ............................................................................................................................... 42

Regenerative Cycle: .................................................................................................................................................... 43

Reheat – Regenerative Cycle: ..................................................................................................................................... 45

STEAM RATE ........................................................................................................................................................... 46

HEAT RATE ............................................................................................................................................................. 46

Turbine Efficiency ................................................................................................................................................... 47

Pump Efficiency ...................................................................................................................................................... 47

Boiler or Steam Generator Efficiency ...................................................................................................................... 47

GENERAL BOILER DESCRIPTION ...................................................................................................................................... 47

Boiler Auxiliaries and Accessories ............................................................................................................................... 49

BOILER PERFORMANCE .............................................................................................................................................. 50

BOILER HEAT BALANCE ............................................................................................................................................... 52

CONDENSERS ................................................................................................................................................................. 57

Direct - contact or Open, condensers ......................................................................................................................... 57

Surface Condenser ..................................................................................................................................................... 58

5

GEOTHERMAL POWER PLANT ........................................................................................................................................ 60

The Diesel Power Plant .................................................................................................................................................. 63

ENGINE PERFORMANCE ............................................................................................................................................. 68

1. Heat supplied by fuel (Qs):.................................................................................................................................. 68

2. Indicated Power (IP): .......................................................................................................................................... 68

3. Brake or Shaft Power (BP): 68

4. Friction Power (FP): ............................................................................................................................................ 69

5. Brake Torque ...................................................................................................................................................... 69

6. Indicated Mean Effective Pressure (Pmi):............................................................................................................ 69

7. Displacement Volume (VD): ................................................................................................................................. 70

8. Specific Fuel Consumption .................................................................................................................................. 70

9. Heat Rate (HR): ................................................................................................................................................... 70

10. Thermal Efficiency ............................................................................................................................................ 71

11. Mechanical Efficiency ....................................................................................................................................... 71

12. Generator Efficiency ......................................................................................................................................... 71

13. Generator Speed .............................................................................................................................................. 71

14. Volumetric Efficiency ........................................................................................................................................ 71

15. Correction Factor for Non-Standard Condition .................................................................................................. 72

16. Engine Heat Balance ......................................................................................................................................... 72

Diesel Engine Maintenance ........................................................................................................................................ 73

Hydroelectric Power Plant.............................................................................................................................................. 83

TERMS AND DEFINITION ............................................................................................................................................ 83

A. IMPULSE TYPE (Pelton type) ................................................................................................................................... 84

B. REACTION TYPE (Francis Type) ............................................................................................................................... 85

6

PUMP STORAGE HYDRO-ELECTRIC PLANT .................................................................................................................. 86

FUNDAMENTAL EQUATIONS .................................................................................................................................. 86

GAS TURBINE POWER PLANT ......................................................................................................................................... 88

Closed Cycle Gas Turbine Cycle .................................................................................................................................. 89

WIND POWER ................................................................................................................................................................ 93

7

POWER PLANT TECHNOLOGY

By. Engr. Yuri G. Melliza

Introduction

This book was designed as standard learning materials intended for graduating technology students in a course of Power Plant technology. This was written with my goal

in mind to focus on the study of different types of electric generating power plant facility used commonly in different parts of the world. With the fast growing global technological

advancement, this book gives the students a wide array of understanding the different

concepts and principles of electrical energy production as well as the analytical and technical design of the different power plant system. On the other hand this book adopts to used the SI system of units, which is now used worldwide as the standard system of units.

TOPIC OUTLINE

1. Introduction to Thermodynamics

2. Fuels and Combustion

3. The Steam Power Plant Cycle

4. The Internal Combustion Engine Power Plant

5. The Hydro-Electric Power Plant

6. The Gas Turbine Power Plant 7. The Geothermal Power Plant

8. The Wind Energy 9. The Solar Energy

10. Energy From the Ocean 11. Cogeneration Power Plant

12. Environmental Aspects of Power Generation

8

υ=

υ=

υ

ρ=ρ=ρ==

υ=ρ=

AvvAvA

AvvAvA

mmm

AvAvm

2

22

1

11

222111

21

Introduction to Thermodynamics

Law of Conservation of Mass

Mass is indestructible, in applying this law we must except nuclear processes during which mass is converted into energy.

Verbal Form:

Mass Entering – Mass Leaving = Change of Mass stored in the system

Equation Form: m1 – m2 = ∆m

For a steady-state, steady flow ∆m = 0, hence

m1= m2

Continuity Equation

For one dimensional flow

Where: m – mass flow rate in kg/sec

A – cross sectional area in m2 v – velocity in m/sec

ρ - density in kg/m3

υ - specific volume in m3/kg

1 2 m m

9

∫ ⋅= dxFW

Forms of Energy

• Internal Energy • Flow Energy or Flow Work

• Heat • Work • Kinetic Energy • Potential Energy

Internal Energy: It is the energy due to the overall molecular interaction.

∆U = m(u2 – u1) KJ

Where: u – specific internal energy, KJ/kg

U – total internal energy, KJ (KW if m in kg/sec) m – mass in kg (kg/sec, mass flow rate)

Flow Energy or Flow Work: It is the energy required in pushing a fluid into the system or out from the system.

∆(PV) = (P2V2 – P1V1) KJ

∆(Pυ) = (P2υ2 – P1υ1) KJ/kg

Where: P – pressure, KPa V – volume, m3

υ - specific volume, m3/kg

PV – flow work, KJ (KW if V in m3/sec) Heat: Heat is the energy that srosses a system’s boundary because of a temperature

difference between the system and the surrounding. Q = m(q) KJ Where:

Q – Total heat, KJ (KW if m in kg/sec)

q – heat in KJ/kg Note: Q is positive if heat is added to the system and negative if heat is rejected

from the system

Work: Work is define as the force multiplied by the displacement in the direction of the force.

10

( )KJ

2(1000)

)vvmΔKE

2

1

2

2 −=

( )KJ

(1000)

zzmgΔPE 12 −=

Ckg

KJor

K-kg

KJ

°−°=

dT

dQC

Kinetic Energy: It is the energy due to the motion of a body.

Where:

v – velocity, m/sec m – mass, kg

KE – Kinetic energy, KJ (KW if m in kg/sec)

Potential Energy: It is the energy by virtue of its configuration or elevation.

Where: z – elevation measured from a chosen datum, meters

+ z if measured above the datum - z if measured below datum

g – gravitational acceleration, m/sec2 g = 9.81 m/sec2 (at sea level condition)

PE – potential energy, KJ (KW if m in kg/sec)

Zeroth Law of Thermodynamics:

If two bodies are in thermal equilibrium with a third body, they are in thermal

equilibrium with each other and hence their temperatures are equal. Specific Heat or Heat Capacity:

Specific heat is the amount of heat required to raise the temperature of a 1 kg

mass of a substance 1°K or 1°C.

dQ = C dT If C is constant

Q = C(T2 – T1) KJ/kg

Considering m; Q = mC(T2 – T1) KJ (KW if m in kg/sec)

11

Sensible Heat: It is the amount of heat added to heat a substance, or the amount of

heat removed to cool a substance. Q = mC(T2 – T1) KJ (KW if m in kg/sec

Heat of Transformation

A. Latent Heat of Vaporization: It is the amount of heat added to vaporize a

liquid, or the amount of heat removed to condense a gas (Vapor) Qv = m(Hv) KJ (KW if m in kg/sec)

Where:

m – mass in kg (kg/sec) Hv – heat of vaporization in KJ/kg

B. Latent Heat of Fusion: It is the amount of heat added to melt a solid or

removed to solidify a liquid. QF = m(HF) KJ (KW if m in kg/sec)

Where:

HF – latent heat of fusion in KJ/kg

Phase Change

A. Vaporization: Liquid to Vapor

B. Condensation: Vapor to liquid C. Freezing or Solidifying: Liquid to solid

D. Melting: Solid to liquid E. Sublimation: Change from solid directly to vapor without passing the liquid

state.

12

CT

VP

T

VP

CT

PV

RTP

mRTPV

2

22

1

11 ==

=

==

υ

K-kg

KJ

oM

3143.8R =

2211 VPVP

CPV

==

)( TmChQ

T

V

T

V

CT

V

P

2

2

1

1

∆=∆=

=

=

)( TmCUQ

T

P

T

P

CT

P

V

2

2

1

1

∆=∆=

=

=

Ideal or Perfect Gas

Fundamental equations:

1. Equation of State or Perfect Gas Equation

2. Gas Constant

3. Boyles Law (At constant temperature, T = C)

4. Charle’s Law

a. At Constant Pressure

b. At Constant Volume

13

1k

RkCP −

=

v

p

vp

V

C

Ck

RCC

1k

RC

=

+=−

=

∫=∆T

dQS

2

1

2

1

M

M=

γγ

5. Avogadro’s Law: All gases at the same temperature and pressure have the

same number of molecules per unit of volume. It follows that the specific weight is directly proportional to its molecular weight.

6. Specific Heat

a. At Constant pressure

b. At Constant volume

7. Entropy Change

14

∑= inn

n

ny i

i =

∑= imm

m

mx i

i =

mRTPV =

iiiii TRmVP =

TRnPV =

iiii TRnVP =

IDEAL GAS MIXTURE

Gas Mixture: A gaseous substance consisting two or more type of gases. The gases in a gas mixture are called “components” or “constituents” of a mixture.

1. Total moles of a mixture

2. Mole Fraction

3. Total mass of a mixture

4. Mass Fraction

5. Equation of State

A. Mass Basis a. For the mixture

b. For the components

B. Mole Basis a. For the mixture

b. For the components

15

V

Vy

VV

VVVV

P

TR

TR

PV

TR

PV

TR

PV

TR

PV

TR

PV

TR

PV

TR

PV

TR

PV

nnnn

ii

i

321

321

321

321

=

=

++=

++=

++=

++=

∑

P

Py

PP

PPPP

V

TR

TR

VP

TR

VP

TR

VP

TR

PV

TR

VP

TR

VP

TR

VP

TR

PV

nnnn

ii

i

321

321

321

321

=

=++=

++=

++=

++=

∑

6. Amagat's Law: The total volume V of a mixture is equal to the sum of the volume

occupied by each component at the mixture pressure P, and temperature T.

7. Dalton's Law: The total pressure of a mixture P is equal to the sum of the partial

pressure that each gas would exert at the mixture volume V and temperature T.

1

n1 V1

2

n2 V2

3

n3 V3

P, T P = P1 = P2 = P3 T = T1 = T2 = T3

1

n1 P1

2

n2 P2

3

n3 P3

mixture

n2

P2

V = V1 = V2 = V3 T = T1 = T2 = T3

16

mol

ii

kg

kg

R

31438

R

RM

MyM

.==

=∑

K-kg

KJ

M

31438

M

RR

RxR ii

°==

=∑.

K-kg

KJ

1k

RC

K-kg

KJ

1k

RkC

K-kg

KJ RCC

K-kg

KJ CxC

K-kg

KJ CxC

V

P

VP

ViiV

PiiP

°−=

°−=

°+=

°=

°=

∑

∑

M

My

My

Myx ii

ii

iii ==∑

8. Molecular Weight of a Mixture

9. Gas Constant of a mixture

10. Specific Heats of a mixture

11. Gravimetric and Volumetric Analysis: Gravimetric Analysis gives the mass

fractions of the components in the mixture. Volumetric Analysis gives the volumetric

or molal fractions of the components in the mixture. A . Volumetric or Molal analysis to Gravimetric analysis

17

PdVdUdQ

dVPdW

+=⋅=

⋅=

+=

∫ dVPW

WΔUQ

∑=

i

i

i

i

i

M

x

M

x

y

B. Gravimetric analysis to volumetric or Molal analysis

Law of conservation of Energy (The First Law of Thermodynamics):

“Energy can neither be created nor destroyed but can only be converted from one form to another.”

Verbal Form: Energy Entering – Energy Leaving = change of energy stored in the system

Equation Form:

E1 – E2 = ∆Es

Application of the Law of Conservation of Energy

A. Closed System (Nonflow System): A system closed to matter or mass flow.

B. Open System (Steady-State, Steady-Flow System): A system opens to

matter flow in which there’s an exchange of mass between the system and the surrounding.

Gas

∆U

Q

W

System

Q

W

1

2

11111 PEKEVPU +++

22222 PEKEVPU +++

18

2

2

1

1

v

p

v

p

T

V

T

V

C

Ck

1k

RC

1)k

RkC

=

=

−=

−=

From First Law;

E1 – E2 = ∆Es

For an Open system, ∆Es = 0, hence

E1 = E2 or Energy entering = Energy leaving

Enthalpy: Sum of internal and flow energy

h= U + PV

Processes of Fluids

1. Isobaric Process: Reversible Constant Pressure Process

A. Closed System Q = ∆U + W

W = P(V2 – V1) Q = m(h2 – h1)

∆U = m(u2 – u1)

For Ideal Gas

Q = mCp(T2 – T1) ∆U = mCv(T2 – T1)

W = mR(T2 – T1)

WPEPEKEKEVPVPUUQ

WPEKEVPUQPEKEVPU

1212112212

2222211111

+−+−+−+−=++++=++++

)()()()(

[ ]-PE-KE-h-QW

PEPEKEKEhh-QW

WPEPEKEKEhhQ

WPEKEhQPEKEh

121212

121212

222111

∆∆∆=−+−+−=

+−+−+−=+++=+++

)()()(

)()()(

19

B. Open System (Steady-state,steady-flow)

W = -∆KE - ∆PE

If ∆KE = 0 & ∆PE = 0

W = 0 Q = m(h2 – h1)

C. Entropy change

2. Isometric Process: Reversible Constant Volume Process.

A. Closed System (Non-Flow) Q = ∆U + W

W = 0 ∆U = m(u2 – u1)

Q = ∆U = m(u2 – u1)

For Ideal Gas

Q = mCv(T2 – T1) Q = ∆U = mCv(T2 – T1)

W = 0

2

2

1

1

v

p

v

p

T

P

T

P

C

Ck

1k

RC

1)k

RkC

=

=

−=

−=

B. For Open System (Steady flow)

)P--V(PW

h-QW

0PE& 0KE If

PE-KE-)P--V(PW

-PE-KE-h-QW

12

12

=∆=

=∆=∆∆∆=

∆∆∆=

gas idealFor T

Tln

PmCΔS

SSΔS

1

2

12

→=

−=

20

For Ideal Gas

C. Entropy Change

3. Isothermal Process: Reversible Constant Temperature Process

A. Closed System (Nonflow System) Q = ∆U + W

∆U = m(u2 – u1)

For Ideal Gas

P1V1 = P2V2 = C ∆U = mCv(T2 – T1)

T2 – T1 = 0 ∆U = 0

Q = W

B. For Open System (Steady Flow)

)TmR(T)PV(P

)PV(P)PV(P

2112

2112

−=−−−=−−

1

211

2

111

1

211

2

111

p

V

Vln VP

P

Pln VPW

QW

0ΔPE& 0ΔKE If

V

Vln VP

P

Pln VPQ

ΔPE-ΔKE-QW

0 Δh

0 ΔT

T)( mCh

Gas IdealFor

ΔPE-ΔKE-Δh-QW

==

===

==

===

∆=∆

=

gas idealFor T

TlnmCΔS

SSΔS

1

2V

12

→=

−=

111

2

111

1

211

mRTVP

P

PlnVP

V

VlnVPW

=

==

21

1

2

1

1

1

2

1

2

2211

−−

=

=

==k

k

k

kk

V

V

P

P

T

T

CVPVP

ΔUW

0Q

WΔUQ

−==

+=

−

−==∆=

==

−

−==

−∆==

−−−=

−

−

1P

P

k1

kmRT

k-1

)VP-Vk(Ph-W

0ΔPE& 0ΔKE If

1P

P

k1

kmRT

k-1

)VP-Vk(PΔh-

gas idealFor

ΔPEΔKE-h-W

0Q

ΔPEΔKEΔhQW

k

1k

1

211122

k

1k

1

211122

−

−=

−−

=

−−=−=−

1P

P

k1

mRT

k1

)VPV(PW

)T(TmCΔUW

k

1k

1

211122

12v

C. Entropy change

4. Isentropic Process: An isentropic process is an internally reversible adiabatic process in which the entropy remains constant (S = C or PVk = C, for ideal or

perfect gas) P, V, & T relationships for Ideal or Perfect gas

A. Closed System (Non-Flow)

For Ideal Gas

B. Open System (Steady state, steady flow)

gas perfector idealFor T

W

T

QΔS

T

QΔS

SSΔS 12

==

=

−=

22

1n

2

1n

1n

1

2

1

2

n

22

n

11

V

V

P

P

T

T

CVPVP

−−

=

=

==

−−=

−=

−

−=

−−

=

−=+=

−

n1

nkCC

)T(TmCQ

1P

P

n)(1

mRT

n1

)VPV(PW

)TmCv(TΔU

WΔUQ

Vn

12n

n

1n

1

211122

12

ΔhQW

0ΔPE&0KE If

n1

nkCC

)T(TmCQ

1P

P

n)(1

nmRT

n1

)VPVn(PΔhQ

)T(TmCΔh

ΔPEΔKEΔhQW

Vn

12n

n

1n

1

211122

12P

−===∆

−−=

−=

−

−=

−−

=−

−=−−−=

−

1

2n

T

Tln mCΔS =

C. Entropy change ∆S = 0

5. Polytropic Process: A polytropic process is an internally reversible process of an Ideal or Perfect Gas in which PVn = C, where n stands for any constant but

not equal to zero.

P,V, & T relationship:

A. Closed System

B. Open System

C. Entropy Change

23

6. Throttling Process: A throttling process is a steady-state, steady-flow process in which W= 0, ∆KE = 0,∆PE = 0 where h = C.

h1 = h2

Properties of Pure Substance: A pure substance is a substance that is

homogeneous in nature and is homogeneous.

a - sub-cooled liquid b - saturated liquid c - saturated mixture d - saturated vapor

e - superheated vapor

Considering that the system is heated at constant pressure where P = 101.325 KPa, the 100°C is the saturation temperature corresponding to 101.325 KPa, and 101.325 KPa

pressure is the saturation pressure at 100°C.

Saturation Temperature (tsat) - is the highest temperature at a given pressure in

which vaporization takes place. Saturation Pressure (Psat) - is the pressure corresponding to the temperature.

Sub-cooled Liquid - is one whose temperature is less than the saturation temperature corresponding to the pressure.

Compressed Liquid - is one whose pressure is greater than the saturation pressure corresponding to the temperature.

Saturated Mixture - a mixture of liquid and vapor at the saturation temperature. Superheated Vapor - a vapor whose temperature is greater than the saturation

temperature.

30°C 100°C

100°C

100°C

100°C

t>100°C

P P P

P P

(a) (b) (c) (d) (e)

Q Q Q Q Q

24

Temperature - Specific volume Diagram (T-υ diagram)

F(critical point)- at the critical point the temperature and pressure is unique. For Steam: At Critical Point, P = 22.09 MPa; t = 374.136°C

Temperature-Entropy Diagram (T-S Diagram)

Region I - sub-cooled or compressed liquid region

Region II- saturated mixture region Region III- superheated vapor region

T

υ

•

a

b c d

e

F

P = C

t > tsat

tsat

tsc

Critical Point

Saturation Curve

T

S

•

a

b c d

e

F

P = C

t > tsat

tsat

tsc

Critical Point

Saturation Curve I

II

III

25

yurigmelliz

Enthalpy-Entropy Diagram (h-S Diagram or Mollier Chart)

The properties h,S,U,and υ at saturated liquid, saturated vapor, sub-cooled or

compressed liquid and superheated vapor condition, can be determined using the Steam

Table. For the properties at the saturated mixture condition, its properties is equal to r = rf + xrfg where r stands for any property, such as h, S, U,and υ, where subscript f refers to

saturated liquid condition and fg refers to the difference in property between saturated

vapor and saturated liquid and x is called the quality.

QUALITY

where: m - mass v - refers to vapor

l - refers to liquid Note: For sub-cooled liquid, its properties are approximately equal to the properties at

saturated liquid which corresponds to the sub-cooled temperature. Terms and Definition

a. Saturated Liquid – a liquid existing at the saturation temperature corresponding the pressure.

b. Saturated Vapor – a vapor existing at the saturation temperature corresponding the pressure.

c. Superheated Vapor – a vapor whose temperature is greater than the saturation temperature corresponding to the pressure.

d. Subcooled Liquid – a liquid whose temperature is less than the saturation temperature corresponding to the pressure.

m

m

mm

mx v

lv

v =+

=

h

S

• F

P = C

Critical Point

Saturation Curve

I

II

III

t = C(constant temperature curve)

26

main steam line

calorimeter

throttling valve

thermometer

calorimeter pressure gauge

main steam line pressure

to main steam line

e. Saturated Mixture – a mixture of liquid and vapor at the saturation temperature

and pressure. f. Saturated Temperature – it is the highest temperature reached by a liquid

heated at certain pressure in which vaporization takes place. g. Saturated Pressure – a pressure corresponding the saturation temperature.

Example: When water is heated at standard pressure (P = 101.325 KPa) it will

boil at 100°C. This temperature is the saturation temperature corresponding 101.325 KPa and the pressure 101.325 KPa is the saturation pressure

corresponding 100°C temperature.

Throttling Calorimeter: An apparatus that is used to determine the quality of

a desuperheated steam flowing in a steam line.

A throttling process is one that is a constant enthalpy process. Steam from the main steam line expands in the calorimeter to the calorimeter pressure and temperature. A

throttling calorimeter is an instrument used to determine the quality of steam flowing in

the main steam line.

27

1.4R

RCvCp

406.11.10

2.14k

1.10

At

2.14Cp

)1595(C

At

p

=+=

==

==

==

=

−==

==

v

v

12v

1212

12p

C

15)-(95C808

)T-(TCQ

C V

1136

t-tT-T

)T-(TCQ

CP

KJ

m 3

7.91W

9.2P

VPV

3.11

2

3.1

112

=

=

=

kg 1)20(5.0V

mV

m

V

n1

VPVPW

CVPVP

1

1122

3.1

22

3.1

11

==υ=

=υ

−−=

==

Example (Constant Pressure – Ideal Gas) When a certain perfect gas is heated at constant pressure from 15ºC to 95ºC, the heat required

is 1136 KJ/kg. When the same gas is heated at constant volume between the same temperatures the heat required is 808 KJ/kg. Calculate Cp, Cv, k, and M of the gas.

Example 2 – (Polytropic – Ideal Gas) A closed system consisting of 2 kg of a gas undergoes a polytropic process during which the value of n = 1.3. The process begins with P1 = 100 KPa, υ1 = 0.5 m3/kg and ends with P2 = 25

KPa. Determine the final volume, in m3, and the work. Given

m = 2 kg P1 = 100 KPa ; P2 = 25 KPa υ1 = 0.5 m3/kg

Process: PV1.3 = C

28

KPa 15.337P

RTmVP

kg 66.45m

)300)(1172.0)(3m()5(300

RTmVP

mRTPV

1

1111

1

1

2222

==

=−=

==

Example 3 – (Ideal Gas) A 5 m3 tank contained chlorine (R = 0.1172 KJ/kg-K) at 300 KPa and 300K after 3 kg of chlorine

has been used. Determine the original mass and pressure if the original temperature was 315 K. (45.66 kg ; 337.15 KPa)

Given V1 = V2 = 5 m3 ; R = 0.1172 KJ/kg-°K

m1 = ? ; P1 = ? ; T1 = 315°K

P2 = 300 KPa ; T2 = 300°K

m2 = (m1 – 3)

Example 4 – (Constant Temperature/Ideal Gas) A mass of kg of air contained in cylinder at 800 KPa, 1000°K expands in a reversible isothermal

process to 100 KPa. Calculate

a. the heat Q b. the entropy change Given: Process T = C or PV = C (for Air: R = 0.287 KJ/kg-°K and k = 1.4)

m = 1 kg ; P1 = 800 KPa ; T1 = 1000°K ; P2 = 100 KPa

a. At T = C for ideal Gas, Q = W

KJ597WQ

100

800ln)1000)(287.0(1

P

PlnmRT

V

VlnmRTWQ

2

11

1

21

==

====

b. K

KJ597.0

1000

597

T

Q S

°===Δ

Example 5 – (Polytropic Process) One kg of oxygen are compressed polytropically from a pressure of 96.5 KPa and 21°C to 675.5

KPa. The ratio of the specific heat k = 1.395 and the compression is according to PV1.3= C. Determine the change of entropy in KJ/K.(∆S = -0.94 KJ/K)

Given: P1 = 96.5 KPa ; P2 =675.5 KPa

k= 1.395 PV1.3 = C

−−=

=∆

n1

nkCC

T

TlnmCS

vn

1

2n

29

Fuels and Combustion

Fuel: A substance composed of chemical elements which in rapid chemical union with

oxygen produced “combustion”. Combustion: Is that rapid chemical union with oxygen of an element whose exothermic heat of reaction is sufficiently great and whose rate of reaction is sufficiently fast

whereby useful quantities of heat are liberated at elevated temperature.

Types of Fuel 1. Solid Fuels

a. Coal b. Wood

c. charcoal 2. Liquid Fuels

a. Diesel

b. Gasoline c. Kerosene

3. Gaseous Fuels a. LPG

b. Natural Gas c. Methane

4. Nuclear Fuels a. Uranium

b. Plutonium Combustible Elements

1. Carbon (C) 2. Hydrogen (H2)

3. Sulfur (S) Complete Combustion: Occurs when all the combustible elements has been fully

oxidized.

Ex. C + O2 → CO2

Incomplete combustion: Occurs when some of the combustible elements has not been fully oxidized.

Ex. C + O2 → CO

30

Molecular Weight of combustion Gases

Gas Molecular Weight

C 12

H 1

H2 2

O 16

O2 32

N 14

N2 28

S 32

Combustion Chemistry

A. Oxidation of Carbon

C + O2 → CO2

Mole Basis

1 + 1 → 1 Mass Basis

1(12) + 1(32) → 1(44)

3 + 8 → 11

B. Oxidation of Hydrogen H2 + ½ O2 → H2O

Mole Basis 1 + ½ → 1

Mass Basis 1(2) + ½(32) → 1(18)

2 + 16 → 18

1 + 8 → 9

C. Oxidation of Sulfur S + O2 → SO2

Mole Basis

1 + 1 → 1

Mass Basis 1(32) + 1 (32) → 1(64)

1 + 1 → 2

31

76321

79

O Mol

N Mols

2

2 .==

C of kg

air of kg4411

3

77638

Carbon of kg

air of kg.

)(. =+=

2

21

H of kg

air of kg 3234

1

147638

Hydrogen of kg

air of kg.

))(.( =+=

Composition of Air: (in theoretical combustion)

%age by Volume (or by mole) O2 = 21

N2 = 79 %age by mass

O2 = 23 N2 = 77

Mole Ratio

Combustion of Combustible elements with Air:

A. Combustion of Carbon with Air C + O2 + 3.76N2 → CO2 + 3.76N2

Mole Basis 1 + 1 + 3.76 → 1 + 3.76

Mass Basis

1(12) + 1(32) + 3.76(28) → 1(44) + 3.76(28)

3 + 8 + 3.76(7) → 11 + 3.76(7)

B. Combustion of Hydrogen with air H2 + ½ O2 + (½)3.76N2→ H2O + (½)3.76N2

Mole Basis 1 + ½ + (½)3.76 → 1 + (½)3.76

Mass basis 1(2) + ½(32) + (½)3.76(28) → 1(18) + (½)3.76(28)

2 + 16 + (½)3.76(28) → 18 + (½)3.76(28) 1 + 8 + (½)3.76(14) → 9 + (½)3.76(14)

32

S of kg

air of kg 294

32

2876332

Sulfur of kg

air of kg.

))(.( =+=

C. Combustion of Sulfur with air

S + O2 + (3.76)N2 → SO2 + 3.76N2

Mole Basis 1 + 1 + 3.76 → 1 + 3.76

Mass Basis 1(32) + 1(32) + 3.76(28) → 1(64) + 3.76(28)

32 + 32 + 3.76(28) → 64 + 3.76(28)

Theoretical Air: It is the minimum amount of air required to oxidized the reactants. With theoretical air alone, no O2 is found in the product.

Excess Air: It is an amount of air in excess of the theoretical air requirement in order to influence complete combustion. With excess air O2 is found in the product.

Hydrocarbon Fuel: Fuels containing the element Carbon and Hydrogen. Chemical Formula: CnHm

Family of Hydrocarbon:

1. Paraffin (CnH2n+2) 2. Olefins (CnH2n) 3. Diolefin (CnH2n-2) 4. Naphthene (CnH2n): this type of fuel has the same formula as olefins but

at different structure. 5. Aromatics ((CnH(2n-6)) COMBUSTION OF HYDROCARBON FUEL(CnHm)

A) Combustion of CnHm with 100% theoretical air

CnHm + aO2+ a(3.76)N2 → bCO2 + cH2O + a(3.76)N2

where:

a = n + 0.25m b = n

c = 0.5m

B) With excess air CnHm + (1+e)aO2 + (1+e)a(3.76)N2 → bCO2 + cH2O +dO2 + (1+e)a(3.76)N2

where:

d = e(n + 0.25m) Note: The values of a,b,c, and d above in terms of n and m is applicable only for the combustion of one type of hydrocarbon.

where: e - excess air in decimal

33

+= 1F

Amm

Fg

Theoretical Air-Fuel Ratio: Ratio of Kg of Air to Kg of fuel

Actual Air-fuel Ratio: Ratio of actual kgs of Air (theoretical + excess) to kg of fuel

COMBUSTION OF SOLID FUELS

Components of Solid Fuels: C, H2, O2, N2, S, and Moisture

A) Combustion with 100% theoretical air

aC + bH2 + cO2 + dN2 + eS + fH2O + xO2 + x(3.76)N2 →

gCO2 + hH2O + iSO2 + jN2

B) Combustion with excess air (e’ - excess air in decimal)

aC + bH2 + cO2 + dN2 + eS +fH2O + (1+e’)xO2 + (1+e’)x(3.76)N2 →

gCO2 + hH2O + iSO2 + kO2 + lN2

The theoretical and actual air-fuel ratio of solid fuels can be computed based on their

balance combustion equation above.

DEW POINT TEMPERATURE The Dew Point Temperature (tdp) is the saturation temperature corresponding the partial pressure of the water vapor in the mixture (products of combustion).

ULTIMATE ANALYSIS

Ultimate Analysis gives the amount of C, H2, O2, N2, S and moisture in percentages by mass, sometimes the percentage amount of Ash is given.

(A/F)t = 11.44C + 34.32(H- O/8) + 4.29S kg of air/kg of fuel

where: C, H, O and S are in decimals obtained from the Ultimate Analysis

PROXIMATE ANALYSIS Proximate Analysis gives the percentage amount of Fixed Carbon, Volatiles, Ash and

Moisture. ORSAT ANALYSIS

Orsat Analysis gives the volumetric or molal analysis of the products of combustion or exhaust gases on a Dry Basis. MASS FLOW RATE OF FLUE GAS

a) Without considering Ash loss:

34

+= loss Ash-1F

Amm

Fg

b) Considering Ash loss

where ash loss in decimal

MOLECULAR WEIGHT OF PRODUCTS

moloductsPr

NNSOSOOOOHOHCOCO

kg

kg

n

nM. . . MnMnMnMnMnM 2222222222

++++++=

K-kg

KJConstant Gas-R

Constant Gas Universal K-kg

KJ 3143.8R

kg

kg

R

RM

mol

mol

°

→°

=

=

GAS CONSTANT OF PRODUCTS

M

RR

K-kg

KJ

m

mR. . . RmRmRmRmRmR

oductsPr

NNSOSOOOOHOHCOCO 2222222222

=

°++++++

=

SPECIFIC HEATS OF PRODUCTS

V

P

VP

ViiV

oductsPr

VNVNSOVSOOVOOHVOHCOVCO

V

PiiP

oductsPr

PNPNSOPSOOPOOHPOHCOPCO

P

C

Ck

RCC

CxC

K-kg

KJ

m

mC. . . CmCmCmCmCmC

CxC

K-kg

KJ

m

mC. . . CmCmCmCmCmC

2222222222

2222222222

=

+=Σ=

°++++++

=

Σ=°

++++++=

Where:

CP – specific heat at constant pressure in KJ/kg-°K or KJ/kg-°C

CV – specific heat at constant volume in KJ/kg-°K or KJ/kg-°C

k – ratio of specific heat

35

5.38.93

3.3M

9.18.93

8.1S

%2.18.93

1.1N

6.28.93

4.2O

%8.42.6100

5.4H

%862.6100

7.80C

2

2

2

==

==

==

==

=−

=

=−

=

PARTIAL PRESSURE OF COMPONENTS

mixture the in components the of pressure partial -P

mixture the of pressure

PP

PyP

i

i

ii

totalP −Σ=

=

EXAMPLE 1 The ultimate analysis of a coal fuel is as follows:

C = 80.7% ; H2 = 4.5% ; O2 = 2.4% ; N2 = 1.1% ; S = 1.8%; M = 3.3% and Ash = 6.2%. Determine

a. The combustion equation b. The air – fuel ratio

c. The HHV and LHV of the fuel d. The M and R of the products

SOLUTION

Reduce the analysis to an ashless basis

36

%91.1937.9

194.0M

%6.0937.9

06.0S

%43.0937.9

043.0N

81.0937.9

08.0O

%2.24937.9

4.2H

%05.72937.9

16.7C

937.9194.006.0043.008.04.216.7Mi

xi

18

5.3

32

9.1

28

2.1

32

6.2

2

8.4

12

86

Mi

xi

2

2

2

==

==

==

==

==

==

=+++++=Σ

+++++=Σ

Converting to molal analysis

Combustion with 100% theoretical air (Basis: 100 moles of fuel)

2222

222222

2

2

2222

222222

N0444.316SO6.0OH11.26CO05.72

N6144.315O94.83)OH91.1S6.0N43.0O81.0H2.24C05.72(

0444.316

N

94.83

d2

11.2605.72x

2

91.1

O

11.26

Hydrogen

b05.72

nceCarbonBala

eNdSOOcHbCO

N)76.3(xxO)OH91.1S6.0N43.0O81.0H2.24C05.72(

+++→+++++++

==+

=

=

→++=++

==+

=

+++→+++++++

e

e)83.94(3.760.43

Balance

x

1 eq. From

d 0.6

Balance S

1 eq. 0.81

Balance

c

c1.9124.2

Balance

37

fuelofkg5.11

54.1004

2832.11523

)18(91.1)32(6.0)28(43.0)32(81.0)2(2.24)12(05.72

)28(6144.315)32(94.83

F

A

air of kg ==

++++++=

EXAMPLE 2 An Ultimate analysis of coal yields the following composition:

C = 74% ; H2 = 5%; O2 = 6%; N2 = 1.2%; S = 1%; M = 3.8% and Ash = 9%. If this coal is burned with 25% excess air, determine

a. The combustion equation

b. The actual air – fuel ratio in kg/kg

Fuel Components

Ultimate analysis

Ashless %

M x/M Molal Analysis

Combustion w/ 100% Theo. air

O2 N2 CO2 H2O SO2 O2 N2

C 74 81.3 12 6.78 67.5 79.44 298.7 67.47 29.66 0.34 299.17

H2 5 5.5 2 2.75 27.4 Combustion w/ excess air e = 0.25

O2 6 6.6 32 0.21 2.1 99.3 373.4 67.5 29.7 0.3 19.9 373.8

N2 1.2 1.3 28 0.05 0.5

S 1 1.1 32 0.03 0.3 Air-Fuel Ratio

M 3.8 4.2 18 0.23 2.3 13.7 kg/kg

Ash 9 10.04 100

100

EXAMPLE 3

A gas turbine generating unit produces 600 KW of power and uses a liquid fuel represented by C8H18 and requires 300% excess air for complete combustion. For a fuel rate of 0.234 kg/KW-hr, determine

a. The combustion equation b. The volume of air required at P = 1500 KPa and T = 310°K

EXAMPLE 4

An unknown hydrocarbon fuel has the following Orsat Analysis: CO2 = 12.5%; CO = 0.3%; O2 = 3.1%; N2 = 84.1% Determine

a. The value of n and m

b. The combustion equation c. The percent excess air (e = 15%)

d. The percent C and H in the fuel

38

HEATING VALUE

Heating Value - is the energy released by fuel when it is completely burned and the products of combustion are cooled to the original fuel temperature.

Higher Heating Value (HHV) - is the heating value obtained when the water in the products is liquid. Lower Heating Value (LHV) - is the heating value obtained when the water in the products is vapor.

For Solid Fuels HHV = 33,820C + 144,212 (H- O/8) + 9304S KJ/kg

where: C, H2, O2, and S are in decimals from the ultimate analysis For Coal and Oils with the absence of Ultimate Analysis

For Liquid Fuels HHV = 31,405C + 141 647H KJ/kg

HHV = 43,385 + 93(°Be - 10) KJ/kg Be - degrees Baume

For Gasoline HHV = 41,160 + 93 (°API) KJ/kg

LHV = 38,639 + 93 (°API) KJ/kg

For Kerosene

HHV = 41,943 + 93 (°API) KJ/kg

LHV = 39,035 + 93 (°API) KJKkg

For Fuel Oils

HHV = 41,130 + 139.6(°API) KJ/kg

LHV = 38,105 + 139.6(°API) KJ/kg

API - American Petroleum Institute

For Fuel Oils (From Bureau of Standard Formula)

Be130

140S

API5.131

5.141S

+=

°+=

HHV = 51,716 – 8,793.8 (S)2 KJ/kg LHV = HHV - QL KJ/kg

QL = 2,442.7(9H2) KJ/kg

H2 = 0.26 - 0.15(S) kg of H2/ kg of fuel S @ t = S - 0.0007(t-15.56)

Where:

S - specific gravity of fuel oil at 15.56 °C H2 - hydrogen content of fuel oil

QL - heat required to evaporate and superheat the water vapor formed by the combustion of hydrogen in the fuel

S @ t - specific gravity of fuel oil at any temperature t

39

Oxygen Bomb Calorimeter - instrument used in measuring heating value of solid and

liquid fuels. Gas Calorimeter - instrument used for measuring heating value of gaseous fuels.

Properties of Fuels and Lubricants

a) Viscosity - a measure of the resistance to flow that a lubricant offers when it is subjected to shear stress. b) Absolute Viscosity - viscosity which is determined by direct measurement of shear resistance.

c) Kinematics Viscosity - the ratio of the absolute viscosity to the density d) Viscosity Index - the rate at which viscosity changes with temperature. e) Flash Point - the temperature at which the vapor above a volatile liquid forms a combustible mixture with air.

f) Fire Point - The temperature at which oil gives off vapor that burns continuously when ignited. g) Pour Point - the temperature at which oil will no longer pour freely.

h) Dropping Point - the temperature at which grease melts. i) Condradson Number(carbon residue) - the percentage amount by mass of the

carbonaceous residue remaining after destructive distillation. j) Octane Number - a number that provides a measure of the ability of a fuel to resist

knocking when it is burnt in a gasoline engine. It is the percentage by volume of iso- octane in a blend with normal heptane that matches the knocking behavior of the fuel.

k) Cetane Number - a number that provides a measure of the ignition characteristics of a diesel fuel when it is burnt in a standard diesel engine. It is the percentage of

cetane in the standard fuel.

40

Boiler or Steam Generator

Steam Turbine

Condenser

Feedwater Pump

1

2

3

ms

QA

QR

W t

W P

1 kg

T P1

1

4'

4 P2 = P3

3 2 2'

S

Cycle

A cycle is a series of two or more processes in which the final state is the same as the initial state.

Steam Power Cycle: A power generating cycle that uses steam or water vapor as the working substance. This cycle differ with an internal combustion engine cycle because the combustion occurs in the boiler, unlike that of an IC engine that combustion occurs inside the working cylinders.

Steam Power Plant Cycle

Rankine Cycle

Components:

a. Steam Turbine b. Condenser

c. Pump d. Steam Generator or boiler

Processes: 1 to 2 – Isentropic Expansion (S = C) 2 to 3 – constant pressure Heat Rejection (P = C)

3 to 4 – Isentropic pumping (S = C) 4 to 1 – Constant pressure Heat Addition (P = C)

41

100% xQQe

S

AB =

A. Turbine Work (Wt) (considering S = C; Q = 0; ∆KE = 0; ∆PE = 0)

Wt = ms(h1 – h2) KW

Where: ms – steam flow rate, kg/sec

h – enthalpy, KJ/kg Wt – turbine power, KW

B. Heat Rejected in the Condenser (QR)

QR = m(h2 – h3) KW

C. Pump Work (WP) WP = m(h4 – h3)

D. Heat added to Boiler (QA)

QA = m(h1 – h4) KW

E. Thermal efficiency

F. Net Work W = Wt - Wp

G. Boiler Efficiency (EB)

100% xQWe

100% xHeat Added

WorkNet e

A

=

=

42

Reheat Cycle Steam Power Plant: In a reheat cycle, after partial expansion of steam

in the turbine the steam re-enters a section in the steam generator called the re-heater and re-heating the steam almost the same to initial temperature and then re-expands

again to the turbine. This will result to an increase in thermal efficiency of the cycle, with significant increase in turbine work and heat added.

WP

QR

Wt

QA

1 2 3

4

5

6

1 kg

To Reheater

From Reheater

T

1

S

2

3

4 5

6

43

[ ] KW hhhhmW 4321st −+−= ()(

KW )hh(mQ 54sR −=

KW hhmW 56sP )( −=

[ ] KW hhhhmQ 2361sA )() −+−=

Turbine Work

Heat Rejected

Pump Work

Heat Added

Where: ms – mass flow rate of steam, kg/sec

Regenerative Cycle: In a regenerative cycle some of the steam after initial expansion

is extracted for feed-water heating by mixing the bled steam with the condensate or

drains from other heater. The remaining steam re-expands again in the turbine. The

thermal efficiency also increases due to the decrease in heat added to boiler.

WP2

QR

Wt

QA

1

2 3

4

5 6

1 kg

Open Heater

WP1

7

m1

44

[ ]KW hhm1hhmW 3221st ))(()( −−+−=

[ ]KW hhm1mQ 43sR ))(( −−=

KW hhmW

KW hhm1mW

WWW

67s2P

45s1P

2P1PP

)((

))((

−=−−=

+=

[ ]KW hhmQ 71sA )( −=

Let: m – fraction of steam extracted for feed-water heating, kg/kg Turbine Work

Heat Rejected

Pump Work a. Condensate pump (WP1) b. Feed-water pump WP2)

Heat Added

T

1

S

2

3 4

5

6

7

m

(1-m)

(1-m)

1 kg

1 kg

45

Reheat – Regenerative Cycle: In a reheat – regenerative cycle further increase in

thermal efficiency will occur because of the combine effects of reheating and regenerative feed-water heating. Significantly heat added decreases, total pump work

decreases while turbine work increases. Single stage reheat and single stage regenerative cycle that uses an open type feedwater heater

WP2

QR

Wt

QA

1

2

3

4

5

6

1 kg

Open Heater

WP1

7

m1

2

8

(1-m1)

(1-m1)

T

S

1

2

3

4 5

6

7

8

m

1 kg

(1-m)

(1-m)

(1 kg)

46

[ ]KW hhm1hhmW 4321st ))(()( −−+−=

[ ]KW hhm1mQ 54sR ))(( −−=

[ ][ ]

P2P1P

78sP2

56s1P

WWW

KW )h-(hmW

KW hhm1mW

+==

−−= ))((

[ ]KW hhm1hhmQ 2381sA ))(()( −−+−=

KW inwork turbineW

kg/sec in rate flow steamm

where

hr-KW

kg

W

3600mSR

power turbine the on based isSR when

hr-KW

kg

Produced KW

Rate Flow SteamSR

-t

s

t

s

−

=

=

:

KW inwork turbineW

KW in added Heat Q

where

hr-KW

KJ

W

3600QHR

power turbine the on based isHR when

hr-KW

KJ

Produced KW

Supplied HeatHR

-t

A

t

A

:

=

=

Turbine Work

Heat Rejected

Pump Work

Heat Added

STEAM RATE

HEAT RATE

47

100% x W

Wt

100% x Work TurbineIdeal

Work TurbineActual

t

t'

t

=

=

η

η

100% x W

W

100% x Work Pump Actual

Work Pump Ideal

P

PP

P

'

=

=

η

η

100% x Q

Qe

100% x Boiler to supplied Heat Actual

Boiler by Absorbed Heate

s

AB

B

=

=

Turbine Efficiency

Pump Efficiency

Boiler or Steam Generator Efficiency

EXAMPLE

A coal fired steam power plant operates on the Rankine Cycle. The steam enters the turbine at 7000 KPa and 550°C with

a velocity of 30 m/sec. It discharges to the condenser at 20 KPa with a velocity of 90 m/sec. For a mass flow rate of

steam of 37.8 kg/sec, Determine

a. The ideal turbine work in KW

b. The net power produced in KW

c. The thermal efficiency of the cycle

d. The cooling water required in the condenser if cooling water enters at 20°C and leaves at 35°C

e. The coal consumption in kg/hr if the boiler efficiency is 82% and heating value of coal is 32,000 KJ/kg

From Steam Table

h1 =3529.8 ; S1 = 6.9465

h2 = 2288.3 ;x2 = 86.4%

h3 = 251.33; S3 = 0.8321

h4 = 258.43

Solution:

a. W = Q - ∆h - ∆KE - ∆PE

Q = 0 ; ∆PE = 0

Wt = (h1 – h2) - ∆KE

Wt = 46,792.6 KW

b. Wp = 268.38 KW

W = 46,524.2 KW

c. QA = 123,657.8 KW

e = 37.62%

d. QR = 76,997.5 KW

MW = 1225.99 kg/sec

e. mf = 16,965.25 KG/hr

48

GENERAL BOILER DESCRIPTION

1. Fire-Tube boiler: Hot gas is inside the tubes while water on the outside. 2. Water-Tube boiler: Water is inside the tube while hot gas is on the outside.

The fire-tube boiler design uses tubes to direct the hot gases from the combustion process through the boiler to a safe point of discharge. The tubes are submerged in the boiler water and transfer the heat from the hot gases into the water.

Inside a firetube boiler the hot gases travel down the furnace during the combustion process, (first pass). The rear head seals the gasses in the lower portion of the head. The gas is redirected through the second pass tubes. In the front head the hot gasses are sealed from escaping out the stack and turned and redirected through the third pass

tubes. The hot gas travels toward the upper portion of the rear head where it’s turned and directed through the fourth pass tubes. From there, after giving up most of the energy from the combustion process, the gas is directed into the stack and vented to the atmosphere.

The water-tube boiler design uses tubes to direct the boiler water through the hot gases from the combustion process, allowing the hot gases to transfer its heat through the tube wall into the water. The boiler water flows by convection from the lower drum

to the upper drum. Either of the fire-tube or water-tube boiler design concepts is available in what is

popularly known as the packaged boiler, a concept introduced by Cleaver- Brooks in 1931. A packaged boiler is shipped from the manufacturer as a complete assembly, with

burner, control systems, operating and safetycontrols, all piped and/or wired into the assembly. Equipment of this type needs only to be positioned into its intended location,

utility connections made and a means provided to direct the flue gases to a safe point of discharge. Most packaged firetube boilers are available in capacities of 500,000 Btu/hr

up to 26,800,000 Btu/hr output. These boilers are normally rated on the basis of boiler horsepower (BHP) output. One boiler horsepower = 33,472 Btu per hour.

Packaged water-tube boilers, designed for commercial applications, are normally available in sizes as small as 1,200,000 Btu/hr output. Industrial watertube boilers can be provided in packaged format in capacities of up to 134,000,000 Btu/hr.

49

Boiler Auxiliaries and Accessories Superheater – a heat exchanger that is used to increase the temperature of the water vapor greater than the saturation temperature corresponding the boiler pressure.

Evaporator – a heat exchanger that changes saturated liquid to saturated vapor. Economizers – is the heat exchanger that raises the temperature of the water leaving the highest pressure feedwater heater to the saturation temperature corresponding to the boiler pressure.

Air Preheater – is a heat exchanger use to preheat air that utilizes some of the energy left in the flue gases before exhausting them to the atmosphere. Fans – a mechanical machine that assist to push the air in, pull the gas out or both. Stoker – combustion equipment for firing solid fuels (used in water tube boilers)

Burners – combustion equipment for firing liquid and gaseous fuels.

Feedwater pump – a pump that delivers water into the boiler. Pressure Gauge – indicates the pressure of steam in the boiler. Safety Valve – A safety device which automatically releases the steam in case of over pressure.

Temperature Gauge – indicates the temperature of steam in the boiler. Fusible Plug – a metal plug with a definite melting point through which the steam is released in case of excessive temperature which is usually caused by low water level.

Water Walls – water tubes installed in the furnace to protect the furnace against high temperature and also serve as extension of heat transfer area for the feed-water. Gage Glass (Water column) – indicates the water level existing in the boiler. Baffles – direct the flow of the hot gases to effect efficient heat transfer between the hot

gases and the heated water.

50

Furnace – encloses the combustion equipment so that the heat generated will be utilized

effectively. Soot blower – device which uses steam or compressed air to remove the soot that has

accumulated in the boiler tubes and drums. Blowdown Valve – valve through which the impurities that settle in the mud drum are

remove. Sometimes called blow 0ff valve. Breeching – the duct that connects the boiler and the chimney.

Chimney or Smokestack – a structure usually built of steel or concrete that is used to dispose the exhaust gases at suitable height to avoid pollution in the vicinity of

the plant.

BOILER PERFORMANCE

1.Heat Generated by Fuel

Qs = mf (HHV) KJ/hr

Where: mf – fuel consumption, kg/hr

HHV – higher heating value of fuel KJ/kg

2. Rated Boiler Horsepower(RBHp)

a) For Water Tube Type

RBHp = 0.91

HS

b) For Fire Tube Type

RBHp = 1.1

HS

Where: HS – required heating surface, m2

3. Developed Boiler Horsepower (DBHp)

)15.65(2257

)h(hm fss −=HP.Bo.Dev

35,322

)h(hm fss −=HP Bo. Dev.

51

One Boiler Horsepower is equivalent to the generation of 15.65 kg/hr of steam

from water at 100°C to saturated steam at 100°C. The latent heat of vaporization of

water at 100°C was taken at 2257 KJ/kg.

4. Percentage Rating

100% x Bo.Hp Rated

Dev.Bo.Hp%R=

5. ASME Evaporation Units

ASME Evap. Units = ms(hs – hf) KJ/hr

6.Factor of Evaporation (FE)

(2257 ))h(hFE fs −=

7. Boiler Efficiency

100% x (HHV)m

)h(hmη

f

fssB

−=

8. Net Boiler Efficiency

100% x (HHV)m

-)h(hmη

f

fssN

sAuxiliarie−=

9. Actual Specific Evaporation

fuel of kg

steam of kg

mf

Evap. Sp. smActual =

10. Equivalent Evaporation

Equiv. Evap. = ms (FE)

11. Equivalent Specific Evaporation

Equiv. Sp. Evap. = ( ) ms FEmf

52

BOILER HEAT BALANCE

Energy supplied to the boiler by 1 kg of fuel is distributed among the following items in the ASME short-form heat balance, all expressed in units of KJ/kg of fuel.

1. Heat absorbed by steam generating unit

Q1 = fm

)h-(hm fss KJ/kg

Where: ms – steam flow rate in kg/hr

mf – fuel consumption in kg/hr

hs – enthalpy of steam, KJ/kg

hf – enthalpy of fed water, KJ/kg

2. Heat loss due to Dry Flue Gas

Q2 = mdg(1.026)(tg – ta) KJ/kg

Where: mdg – mass of dry flue gas, Kggas/Kgfuel

3. Heat loss due to Moisture in Fuel

Q3 = M(h’- hf’) KJ/kg

Where: h’ – enthalpy of superheated steam at flue gas Temperature, KJ/kg

hf’ – enthalpy of liquid at temperature of fuel entering furnace, KJ/kg

Q3 = M(2493 + 1.926tg – 4.187tf) KJ/kg when tg < 302°C

Q3 = M(2482 + 2.094tg – 4.187tf) KJ/kg when tg > 302°C

4. Heat loss due to moisture from the combustion of hydrogen

Q4 = 9H2(h’- hf’) KJ/kg

Q4 = 9H2 (2493 + 1.926tg – 4.187tf) KJ/kg when

tg < 302°C

Q4 = 9H2 (2482 + 2.094tg – 4.187tf) KJ/kg when

tg > 302°C

53

5. Heat loss due to moisture in air supplied

Q5 = W(1.926)maa(tg – ta) KJ/kg

Q5 = %age saturation(Ws)(1.926)maa(tg – ta) KJ/kg

6. Heat loss due to incomplete combustion

Q6 = 23516Ci KJ/kg

Q6 = 23516 ab

2

C COCO

CO

+ KJ/kg

7. Heat loss due to unconsumed carbon in the refuse

Q7 = 33,820(C - Cab)

Wher: (C - Cab) = (Wr – A)

(Wr – A) = WrCr

Wr = rC-1

A

C – carbon in fuel, kg/kg

Cab – carbon actually burned, kg/kg

Wr – weight of dry refuse kg/kg

Cr – weight of combustible in the refuse, kg/kg

8. Heat loss due radiation and unaccounted-for losses

Q8 = HHV –(Q1 + Q2 + Q3 + Q4 + Q5 + Q6 + Q7)

54

Problems (Steam Generators) 1. A steam generator uses coal as fuel having the ultimate analysis as follows:

C = 72% ; H2 = 5%; O2 = 10%; N2= 1.2%; S = 3.3%; M = 0.1% & A = 8.4% If this coal is burned with 20% excess air, Determine

a) the A/F ratio in kga/kgf b) the volume of wet flue gas at101 KPa and 282°C per kg of coal

c) the %age of CO2 by volume in the dry flue gas

d) the dew point of the products e) the fuel consumption in Metric tons per hour for a steaming capacity of 100 Metric

tons/hour, Factor of Evaporation of 1.15 and a steam generator efficiency of 73%. 2. A water tube boiler generates 7,300 kg of steam per hour at a pressure of1.4 MPa and a quality of 98% when the feed-water is 24°C. Find

a) Factor of Evaporation b) Equivalent Evaporation c) Developed Boiler Horsepower

d) %rating developed if the heating surface is 190 m2 e) Overall efficiency if coal having a HHV of 5000 KCal/kg as fired is used at the rate of

3000 L/hr. 3. A water tube boiler generates 8,000 kg of steam per hour at a pressure of 1.4 MPa and a quality of 985 when the feed-water is 24°C. Find

a) Factor of Evaporation b) Equivalent Evaporation in kg/hr

c) Boiler horsepower developed d) Percent rating developed if the heating surface is 185.9 m2 e) Overall efficiency if coal having a HHV of 20,940 KJ/kg as fired is used at a rate of

1500 kg/hr 4. At a load of 43,000 KW in a steam turbine generating set, 3600 RPM, the following data

appear in the log sheet. Steam flow -190 Metric Tons/hour Steam pressure - 8.93 MPaa

Steam temperature - 535C Feed-water temperature - 230C

Fuel Flow: Bunker Oil -3.4 Metric Tons/hr

HHV =10,000 KCal/hr

Local coal -18 Metric Tons/hr HHV = 5350 KCal/hr

Determine thee overall boiler efficiency. h at 8.93 MPa and 535°C - 3475.7 KJ/kg

hf at 230°C- 990.12 KJ/kg

5. A coal fired steam boiler uses 3000 kg of coal per hour. Air required for combustion is 15.5 kg/kg of coal at a barometric pressure of 98.2 KPa. The flue gas has a temperature of 285°C

and an average molecular weight of 30. Assuming an ash loss of 11% and allowable gas

velocity of 7.5 m/sec, find the diameter of the chimney. (D = 1.91 m) 6. Two boilers are operating steadily on 136,500 kg of coal contained in a bunker. One boiler is

producing 2386 kg of steam/hr at 1.15 FE and an efficiency of 75%, and the other boiler produces 2047 kg of steam/hr at 1.10 FE and an efficiency of 70%. How many hours will the coal in the bunker run the boilers if the heating value of the coal is 32,000 KJ/kg. (281.5 hrs)

55

7. An industrial plant is to be designed based upon the following requirements; 5000 KW output

and generator efficiency of 98%. Steam is extracted at the rate of7.6 kg/sec at 0.2 MPa for industrial use. Turbine inlet pressure is 1.2 MPa and temperature of 260C, exhaust at 0.014

MPa. Brake turbine efficiency is 75%. Extracted and exhaust steam are returned to the boiler as liquid at 93C, respectively. Determine a) Supplied steam to the turbine in kg/hr

b) Total heat supplied to the boiler in KJ/hr At 1.2 MPa and 260C

h = 2957.6 KJ/kg S = 6.8721 KJ/kg-K At 93C; hf = 389.54 KJ/kg

At 0.014 MPa Sf = 0.7366 KJ/kg-K ; sfg = 7.2959 KJ/kg-K

hf = 219.99 KJ/kg ; hfg = 2376.6 KJ/kg At 0.2 MPa sf = 1.55301 KJ/kg-K ; sfg = 5.5970 KJ/kg-K

hf = 504.7 KJ/kg ; hfg = 2201.9 KJ/kg At S1 = S2 to 0.20 MPa ;

h2 = 2606.28 KJ/kg At S3 = S4 to 0.014 MPa

h3 = 2218.596 KJ/kg 8. In a test of a Bobcock and Wilcox boiler with hand-fired furnace, the following date were taken;

Rated HP - 350 Grate Surface - 2.323 m2

Duration of test - 24 hours Steam pressure - 1.2 MPa Feed-water temperature - 34C

Quality of steam formed - 99% Total weight of coal fired (wet) - 7110 kg

Moisture in coal - 7.5%

Total weight of water fed to boiler - 54,000 kg Determine:

a) Factor of Evaporation b) Dry coal per m2 of grate surface per hour

c) Equivalent evaporation per hr - m2 of heating surface d) Equivalent evaporation per hour e) Boiler HP Developed

f) Percentage of Rated capacity developed g) The equivalent evaporation per kg of dry coal

h) Combined efficiency of boiler, furnace and grate if the coal has a heating value of 28,590 KJ/kg 9. Coal with HHV = 6700 KCal/kg is consumed at the rate of 600 kg/hr in a steam generator

with a Rated Boiler HP of 200. The feed-water temperature is 82C and steam generator is at 1.08 MPaa saturated. The Developed Boiler HP is equivalent to 305. Determine:

a) Heating Surface, m2 b) Rate of steam generated, kg/hr c) Percentage Rating

d) ASME Evaporation units, J/hr

56

e) Factor of Evaporation f) Overall thermal efficiency

g) Actual specific evaporation, kg steam/kg of coal h) Equivalent specific evaporation

10. The boiler, furnace and grate efficiency of a steam generator is 82%. Coal with a moisture content of 12% is burned at the rate of 10,000 kg per hour. The heating value per kg of dry coal is 28,000 KJ. Steam is generated at 3.2 MPa and a temperature of 320C. Feed-water

temperature is 95C. Determine: a) the kg of steam generated per hour

b) the Developed Boiler Hp. c) the Equivalent evaporation in kg per kg of coal as fired d) the cost to evaporate 500 kg of steam if coal costs P 150 per Metric Ton

57

CONDENSERS

Direct - contact or Open, condensers

This type of condenser are used in special cases, such as when dry cooling towers are used in

geothermal power plants and in power that use temperature differences in ocean waters

(OTEC). Modern direct contact condensers are of the spray type. Early designs were of the

barometric or jet type.

By mass balance m2 = m4

m3 = m2 + m5

By Energy balance m2h2 + m5h5 = m3 = h3

And the ratio of circulating water to steam flow

Turbine

exhaust

Dry cooling

tower

Condenser

Noncondensables

to SJAE

Pump

To plant feedwater

system

2

3 4

5

Schematic Diagram of a Direct - contact condenser

of the Spray type

53

32

2

5

hh

hh

m

m

−−=

58

Surface Condenser

Let Q = QR = Qw

QR – heat rejected by steam

Qw – heat absorbed by cooling water ms – steam flow rate in kg/sec mw – cooling water flow rate in kg/sec twA – inlet temperature of cooling water in °C

twB – outlet temperature of cooling water in °C

Cpw = 4.187 KJ/kg-°C (specific heat of water)

QR = Qw

QR = ms(h2 – h3) KW

Qw = mw Cpw (twB – twA)

Water in mw twA

Water out mw twB

Water box

Turbine

exhaust h2

Condensate

h3

Tubes

Support

Plate

ms

ms

59

In terms of Overall coefficient of heat transfer U:

Csteam, of etemperatur saturation

LMTD

tubes ofnumber total - N

m tubes, of length -L

m tubes, ofdiameter outside

m area, surfacetransfer heat

C,difference etemperatur mean log

K-m

Wor

C-m

W intransfer heat of tcoefficien overall - U

:where

KW

t

2

22

°−−−−

=

−π=

−°−

°

=

s

wBs

wAs

wAwB

t

t

tt

ttln

tt

D

)N(DLA

totalA

LMTD

1000

)LMTD(UAQ

TTD – Terminal Temperature difference TTD = ts - twB

TEMPERATURE – AREA DIAGRAM

1

2

12

wBs1

wAs2

ln

LMTD

tt

tt

θθ

θ−θ=

−=θ−=θ

T

A

twA

ts

twB θ2

θ1

60

Problem A 10,000 KW turbine generator uses 5 kg/KW-hr of steam at rated load. Steam supply pressure is 4.5 MPa and 370°C and the pressure in the surface condenser is 3.4 KPa (tsat = .

Temperature of inlet circulating water is 16°C and outlet of 22°C. Combined efficiency of the

turbo-generator set is 92%. The condenser tubes are 2 mm; 1.2 mm thickness. Water velocity is 3.5 m/sec. Overall coefficient of heat transfer U = 4 W/m2-°C. Tube sheet thickness is 10 mm.

Determine:

a. Cooling water required in L/min

b. Number of tubes for 2-Pass design c. Actual length of tubes

Other Data are as follows: h1 = 3131.4 ;S1 = 6.5897

h2 = 1967.1 ;S2 = 6.5897 x2 = 76.17 h3 = 109.75 ;S3 = 0.3836 h4 = 114.27

GEOTHERMAL POWER PLANT

Geothermal energy is the power obtained by using heat from the Earth's interior. Most geothermal resources are in regions of active volcanism. Hot springs, geysers, pools of boiling mud, and fumaroles (vents of volcanic gases and heated groundwater) are the

most easily exploited sources of such energy The most useful geothermal resources are hot water and steam trapped in subsurface formations or reservoirs and having temperatures ranging from 176° to 662° F (80° to 350° C). Water and steam hotter than 356° F (180° C) are the most easily exploited for

electric-power generation and are utilized by most existing geothermal power plants. In these plants hot underground water is drilled from wells and passes through a separator-collector where the hot water is flashed to steam, which is then used to drive a steam turbine whose mechanical energy is then converted to electricity by a

generator.

61

IDEAL TURBINE WORK Wt = ms(h1 – h2) KW

ACTUAL TURBINE WORK Wt’ = ηTms(h1 – h2) KW

Well bottom pressure

well head pressure

Flasher – separator pressure 0

H

1

2

T

S

3

B

62

wells 788,400

N

kg/hr 788,400 kg/sec

)hm-(mhmhm

1 eq.

mmm

collector -flasher the on balance energy and mass By

kg/sec

wells

Bso1soo

Bso

4000,195

219)hh

)hh(mm

mmm

45m

)1.23414.2786)(80.0(m16000

)hh(m80.0W

Bo

B1so

soB

s

s

21s0

==

==−

−=

+=→−=

+=

=−=

−=

GENERATOR POWER OUTPUT

W0 = ηGηTms(h1 – h2) KW

where ms – steam flow rate in kg/sec

ηT - turbine efficiency

ηG – generator efficiency

o– underground water H – well head condition

1 – saturated vapor condition leaving flasher – separator B – saturated liquid condition leaving flasher – separator

2 – turbine exhaust 3 – saturated liquid leaving condenser

Example A geothermal power plant has an output of 16,000 KW and mechanical - electrical efficiency of 80%. The pressurized groundwater at 17.0 MPa, 280°C leaves the well to enter the flash

chamber maintained at 1.4 MPa. the flash vapor passes through the separator - collector to enter the turbine as saturated vapor at 1.4 MPa. the turbine exhaust at 0.1 MPa. The unflashed water runs to waste. If one well discharges 195,000 kg/hr of hot water, how many wells are

required. ( 4 wells)

From Steam Table At 17,000 KPa and 280°C

ho = 1231.7 KJ/kg

At 1400 KPa Saturated Vapor h1 = 2786.4 KJ/kg ; S1 = 6.4642 KJ/kg-K

At S1 = S2 to 100 KPa h2 = 2341.1 KJ/kg At 1400 KPa saturated Liquid

hB = 829.6 KJ/kg

63

Fuel Tank

Engine Generator

Cooling Tower

Fuel Pump

Cooling water Pump

Air in

Air out The Diesel Power Plant

Two stroke cycle engine: An engine that completes one cycle in one revolution of the crankshaft. Four stroke cycle engine: An engine that completes one cycle in two revolution of the

crankshaft. TERMS AND DEFINITIONS

Diesel engine is a type of internal combustion engine that uses low grade fuel oil and which burns this fuel inside the cylinder by heat of compression. It is used chiefly for heavy-duty work. Diesel engines drive huge freight trucks, large buses, tractors, and heavy road-building equipment. They are also used to power submarines and ships, and

the generators of electric-power stations in small cities. Some motor cars are powered by diesel engines.

Gasoline engine - is a type of internal combustion engine, which uses high grade of oil. It uses electricity and spark plugs to ignite the fuel in the engine's cylinders.

Kinds of diesel engines. There are two main types of diesel engines. They differ according to the number of piston strokes required to complete a cycle of air compression, exhaust, and intake of fresh air. A stroke is an up or down movement of a piston. These engines are (1) the four-stroke cycle engine and (2) the two-stroke cycle

engine. Four Stroke Cycle Engine 1. Intake 2. Compression

3. Power 4. Exhaust In a four-stroke engine, each piston moves down, up, down, and up to complete a cycle. The first down stroke draws air into the cylinder. The first upstroke compresses the air.

64

The second down stroke is the power stroke. The second upstroke exhausts the gases

produced by combustion. A four-stroke engine requires exhaust and air-intake valves. It completes one cycle in two revolutions of the crankshaft.

Two Stroke Cycle Engine

1. Intake-Compression stroke 2. Power-exhaust stroke

In a two-stroke engine, the exhaust and intake of fresh air occur through openings in the cylinder near the end of the down stroke, or power stroke. The one upstroke is the

compression stroke. A two-stroke engine does not need valves. These engines have twice as many power strokes per cycle as four-stroke engines, and are used where high

power is needed in a small engine. It completes one cycle in one revolution of the crankshaft.

Governor - is a device used to govern or control the speed of an engine under varying

load conditions. Purifier - a device used to purify fuel oil and lube oil. Generator - a device used to convert mechanical energy.

Crank scavenging - is one that the crankcase is used as compressor. Thermocouple - is made of rods of different metal that are welded together at one end.

Centrifuge - is the purification of oil for separation of water. Unloader - is a device for automatically keeping pressure constant by controlling the

suction valve. Planimeter - is a measuring device that traces the area of actual P-V diagram.

Tachometer - measures the speed of the engine. Engine indicator - traces the actual P-V diagram.

Dynamometer - measures the torque of the engine. Supercharging - admittance into the cylinder of an air charge with density higher than

that of the surrounding air. Bridge Gauge - is an instrument used to find the radial position of crankshaft motor

shaft.

Piston - is made of cast iron or aluminum alloy having a cylinder form. Atomizer - is used to atomize the fuel into tiny spray which completely fill the furnace in the form of hollow cone. Scavenging - is the process of cleaning the engine cylinder of exhaust gases by forcing

through it a pressure of fresh air. Flare back - is due the explosion of a maximum fuel oil vapor and air in the furnace. Single acting engine - is one in which work is done on one side of the piston. Double acting engine - is an engine in which work is done on both sides of the piston.

Triple-expansion engine - is a three-cylinder engine in which there are three stages of expansion. The working pressure in power cylinder is from 50 psi to 500 psi. The working temperature in the cylinder is from 800°F to 1000°F.

Air pressure used in air injection fuel system is from 600 psi to 1000 psi.

65

Effect of over lubricating a diesel engine is:

Carbonization of oil on valve seats and possible explosive mixture is produced. The average compression ratio of diesel engine is from 14:1 to 16:1.

Three types of piston: 1. barrel type

2. trunk type 3. closed head type

Three types of cam follower:

1. flat type 2. pivot type

3. roller type Methods of mechanically operated starting valve:

1. the poppet 2. the disc type

Three classes of fuel pump: 1. continuous pressure 2. constant stroke

c. variable stroke Type of pump used in transferring oil from the storage to the service tanks:

1. rotary pump 2. plunger pump

3. piston pump 4. centrifugal pump

Valve that is found in the cylinder head of a 4-stroke cycle engine: 1. fuel valve

2. air starting valve 3. relief valve

4. test valve 5. intake valve

6. exhaust valve

Four common type of governors used on a diesel engine: 1. constant speed governor 2. variable speed governor 3. speed limiting governor

4. load limiting governor Kinds of piston rings used in an internal combustion engines: 1. compression ring 2. oil ring

3. firing ring 4. oil scraper ring Reasons of smoky engine: 1. overload

2. injection not working 3. choked exhaust pipe

66

4. fuel or water and leaky things

Methods of reversing diesel engines: 1. sliding camshaft

2. shifting roller c. rotating camshaft

Arrangements of cylinders: 1. in-line

2. radial 3. opposed cylinder

4. V 5. opposed piston

Position of cylinders:

1. vertical 2. horizontal

3. inclined Methods of starting: 1. manual, crank, rope, and kick

2. electric (battery) 3. compressed air

4. using another engine Applications:

1. automotive 2. marine

3. industrial 4. stationary power

5. locomotive 6. aircraft

Types of internal combustion engine: 1. Gasoline engine

2. Diesel engine

3. Kerosene engine 4. Gas engine 5. Oil-diesel engine Methods of ignition:

1. Spark 2. Heat of compression Reasons for supercharging: 1. to reduce the weight to power

ratio 2. to compensate the power loss due to high altitude Types of superchargers:

1. engine-driven compressor 2. exhaust-driven compressor

67

3. separately-driven compressor

Auxiliary systems of a diesel engine: 1. Fuel system

a. fuel storage tank b. fuel filter

c. transfer pump d. day tank

e. fuel pump 2. Cooling system

a. cooling water pump b. heat exchanger

c. surge tank d. cooling tower

e. raw water pump

3. Lubricating system: a. lub oil tank

b. lub oil pump c. oil filter

d. oil cooler e. lubricators

4. Intake and exhaust system a. air filter

b. intake pipe c. exhaust pipe

d. silencer 5. Starting system

a. air compressor b. air storage tank

Advantages of diesel engine over other internal combustion engines:

1. low fuel cost 2. high efficiency 3. needs no large water supply 4. no long warm-up period

5. simple plant layout Types of scavenging: 1. direct scavenging 2. loop scavenging

3. uniflow scavenging Color of the smoke: 1. efficient combustion - light brown baze 2. insufficient air - black smoke

3. excess air - white smoke Causes of black smoke:

68

hr

KJ HVmQs F )(=

KW 604

NnLDPIP

2mi

)(

'π=

KW 604

NnLDPBP

2mb

)(

'π=

1. fuel valve open too long

2. too low compression pressure 3. carbon in exhaust pipe

4. overload on engine Causes of white smoke:

1. one or more cylinders not getting enough fuel 2. too low compression pressure

3. water inside the cylinder

ENGINE PERFORMANCE

1. Heat supplied by fuel (Qs): Total heat supplied by fuel.

Where: mF – fuel consumption in kg/hr

HV – heating value of fuel in KJ/kg

2. Indicated Power (IP): Power developed within the working cylinders.

Where: Pmi – indicated mean effective pressure in KPa

L – length of stroke in meters D – diameter of bore in meters

N – no. of RPM

n’ – no. of cylinders Note: N = (RPM) for 2-stroke, single acting N = 2(RPM) for 2-stroke, double acting

N = (RPM) for 4-stroke, single acting 2 N = (RPM) for 4-stroke, double acting

3. Brake or Shaft Power (BP): Power delivered by the engine to the shaft.

69

KW 00060

TN2BP

,

π=

BPIPFP −=

m-N RTarePT )( −=

KPa L

SAPmi '

''=

Where:

Pmb – brake mean effective pressure in KPa Note:

N = (RPM) for 2-stroke, single acting N = 2(RPM) for 2-stroke, double acting

N = (RPM) for 4-stroke, single acting 2

N = (RPM) for 4-stroke, double acting

Brake Power in Terms of torque:

Where: T – brake torque in Newton – meter (N-m)

Note: N - RPM

4. Friction Power (FP): Power due to friction.

5. Brake Torque

Where:

P – Gross load on scales in Newton Tare – tare weight, N

R – Length of brake arm in meters

6. Indicated Mean Effective Pressure (Pmi): Average pressure exerted by the

working substance (air-fuel mixture) on the piston to produce the indicated power.

Where: A’ – area of indicator card, cm2 S’ – spring scale in KPa/cm

L’ – length of indicator card, cm

70

sec

m

604

NnLDV

sec

m

P

BPV

sec

m

P

IPV

32

D

3

mb

D

3

mi

D

)(

'π=

=

=

hr-KW

kg

IP

mm F

Fi =

hr-KW

kg

BP

mm F

Fb =

KW inpower generator - GP

where

hr-KW

kg

GP

mm F

Fc

:

=

hr-KW

KJ

IP

HVm

IP

QsHRi F )(

==

7. Displacement Volume (VD):

Note: N = (RPM) for 2-stroke, single acting N = 2(RPM) for 2-stroke, double acting

N = (RPM) for 4-stroke, single acting 2 N = (RPM) for 4-stroke, double acting

8. Specific Fuel Consumption

a. Indicated Specific Fuel consumption

b. Brake Specific Fuel consumption

c. Combined Specific Fuel Consumption

9. Heat Rate (HR): Heat rate is the amount of heat supplied divided by the KW produced.

a. Indicated Heat Rate

b. Brake Heat Rate

71

hr-KW

KJ

BP

HVm

BP

QsHRb F )(==

hr-KW

KJ

GP

HVm

GP

QsHRc F )(==

100% x Q

IP3600e

s

i

)(=

100% x Q

BP3600e

s

b

)(=

100% x Q

GP3600e

s

C

)(=

100% x P

P

100% x IP

BP

mi

mbm

m

=η

=η

100% x BP

GPg =η

polesgenerator of no. - n

Hertz of cps in frequency -f

where

RPM n

f120N =

100% x Volume ntDisplaceme

entering airof Volume Actualv =η

c. Combined Heat Rate

10. Thermal Efficiency

a. Indicated Thermal Efficiency (ei)

b. Brake Thermal Efficiency

c. Combined Thermal Efficiency

11. Mechanical Efficiency

12. Generator Efficiency

13. Generator Speed

14. Volumetric Efficiency

72

s

h

h

ssh

T

T

B

BPP =

s

hsh

T

TPP =

h

sshB

BPP =

Be130

140S

API5.131

5.141S

°+=

°+=

15. Correction Factor for Non-Standard Condition

a. Considering Temperature and Pressure Effect

b. Considering Temperature Effect alone

c. Considering Pressure Effect alone

16. Engine Heat Balance

QS = Q1 + Q2 + Q3 + Q4

Q1 - heat converted to useful work

Q2 - heat loss to cooling water Q3 - heat loss to exhaust gases Q4 - heat loss due to friction, radiation and unaccounted for Q1 = 3600(BP) KJ/hr

Q2 = mwCpw(two - twi) KJ/hr Q3 = Qa + Qb KJ/hr Qa = mgCpg(tg - ta) KJ/hr Qb = mf(9H2)(2442.7) KJ/hr

Q4 = QS - (Q1 + Q2 + Q3) KJ/hr H2 = 0.26 - 0.15S kgH/kgfuel

Engine Qs

Q4 Q3

Q2

Q1

73

where:

Qa - sensible heat of products of combustion Qb - heat required to evaporate and superheat moisture formed from the

combustion of hydrogen in the fuel tg - temperature of flue gas, °C

ta - temperature of air, °C H2 - amount of hydrogen in the fuel kg H/kg fuel

Diesel Engine Maintenance

OPERATING A DIESEL ENGINE

Before starting:

There are several steps to be taken before starting a diesel engine, especially he first time,

and its good practice to work out a certain routine to be followed always:

1. All moving parts of the machine much be examined for proper adjustment, alignment, and

lubrication. This includes values, cams, value gear, fuel pumps, the fuel injection, the governor

lubricators, oil and water pumps, and the main driven machinery.

2. The whole engine and machinery must be examined for loose nuts, broken bolts, and loose

connection. And leaky jackets, joint or values. It well to remember that nothing must be tight.

3. All tools from the tool board should be checked to make sure none is missing. They may be

needed in a hurry when the engine is running or, is misplace and left on the engine, may drop off

from vibration and damage some moving parts.

4. All pipes and values for fuel, lubricating oil, water and air, as well as ducts, must be check for

clogging up, lack of adjustment, cleanliness, etc. Absence of foreign matter in the piping system

must be checked especially carefully, if the engine has been idle for sometime or is just being put

into service in the latter case it is advisable to blowout the entire piping system with compressed

air.

5. A complete check up must be given to the lubricating system to make sure that oil is present in

every placed required, that the lubricator and all bearings that are individually oiled have an ample

supply of clean oil, that all grease cups are filled. The lubricator should check for proper functioning

of the pumps and for the amount of oil delivery, and filled with oil to the proper level, the lubricator

should be turned by hands and the points to which its delivers oils should be lubricated. Make sure

that the engine well received proper lubrication the very moment its starts to run.

74

6. The cooling system must checked, and if the pumps are driven by the electronic motors, they must

be started, the suction line opened to have water in the water engine before starting. The correct

amount of water circulation should be adjusted later, while the engine is being warm up. If the

engine has oil-cooled pistons with oil delivered by a especial pump, start the oil pump and adjust

the pressure to the amount stated in the name plate or given in the engine.

7. The fuel-oil system must be checked in every respect, to make sure that pipes are clean, pumps

are working, and a supply of fuel is in the tanks. The fuel-injection pumps should be primed and air

or water removed from the discharge line, valves or nozzles. One or two strokes on the fuel-

injection pump in usually sufficient care should be taken not to force too much fuel the combustion

chamber or cylinder in order not to obtain and excessively high pressure with the first firing-causing

the safety valves to pop and not to get the fuel oil into the crankcase. However, the fuel pumps

must be primed sufficiently so that each discharge line in filled clear to the nozzles, the fuel

controlled level is set wide open so that injection will start at once. The fuel pump control is put in

the fuel on position.

8. The safety valve, usually installed on each cylinder head should be check. These valves are set to

pop off about 750 to 1250 psi, depending upon the maximum pressure allowed in the engine. The

values are exposed to high temperature gases and have a tendency to stick. The checking may be

done either by compressing the spring with crowbar or by unscrewing the cap and taking the valve

out of the inspections.

9.The engine should be turned over one or two times if it has not been operated for sometimes. To do

this it is necessary to open the indicator cocks or compressor-relief valves and to turn the engine

over, either by hands with a bar in the holes in the flywheel, or with a jack or air motor, as the case

maybe. Then the indicator cocks should be close with the same in proper position for starting-one

cylinder having the starting air valve open and the position about 100 past top center.

10. The air in the tanks must be checked to see that it is up to the required pressure. If, not it must be

pumped up the starting air system from the tanks to the starting air control valve must be opened,

either it has been checked that the main control valve is closed. With an air injection engine the

bottle within injection air must be checked and if necessary pumped up o the required pressure.

11. The engine load should be off, the switch should be open if the engine drives a generator, or the

clutch should be in neutral position. If the drive is through the friction clutch. If the engine drives a

pump or compressor, the by-pass should be open.

75

STARTING:

If all eleven points of the preparatory program have been observed starting with compressor

air is very simple.

First, the main starting – air valve is opened and the starting lever is manipulated according to

the instructions given in the engine instruction book.

Second, the engine is watched, no necessary air should be used. At the first indication of

combustion, air should be cut off and the ventilating valve opened, an in good condition usually

begin to between the second and fourth revolution of the crankshaft.

Third, if the engine fills to start after four or five revolution, there is something wrong. Useless

turning of the engine should be stopped, and the cost of trouble investigated.

Low air pressure, if the starting air is too low either from a slow loss of air through some leaky

joint or failure of the engine to start at the first attempt. And there is no air compressors to pump

up air several methods maybe used for securing the necessary starting pressure that never

should pure oxygen by used for starting purposes.

Flasks of compressed air may be obtained and the contents equalized into the engine

receivers, or a flack of carbon dioxide may be obtained from some local soda foundation and

piped to the starting battles. This gas is liquid at ordinary temperatures and about 800-psi

pressures. Therefore, it is necessary to apply some heat in order to evaporate this liquid carbon

dioxide. This heat may be applied by pouring hot water over the battle or by applying rags soaked

in hot water.

WARM UP:

After the engine is started, before putting on the load, its should be allowed to idle for a few

minutes (up to five minutes) and to warm up. During this five minutes the following observations must

be made.

1. Listen to find it out if combustion is regular and firing order and correct all. Cylinder for

combustion and note the working of the fuel injection pump to see whether they all operate

properly.

2. Observe the cooling water system throughout to see whether the pumps are working. There is

sufficient water, watch to see if the water temperature is building up properly, and regulate the

water flow accordingly.

76

3. Observed lubrication pressure and the working of the lubrication and count the number of

drops for correct operation. Feel whether any of the cylinders is warming up too fast –

indicating an unlubricated piston and listen for unlubricated piston pin or crank pin bearing. If

any moving parts receive an insufficient amount of lubricating oil, serious trouble may result.

4. Observe the exhaust, color and sound, to note proper condition. These observations should

be repeated after the lead is put on. The color of the exhaust can tell many things.

The making of these observations during the first five minutes after starting should be

regular habit with the engine operator. This procedure is the best, the most reliable method of

preventing improper operation. It is based upon the fact that a diesel engine requires neither

much, but it requires proper attention at the proper time. It is also based on the known fact that

a diesel engine should be operating properly in five minutes or there is something wrong which

should be detected in these five minutes.

However, it should be noted that certain observations should be carried on even after

the 5-min. warming up period. Thus, if there are any leaky water jackets, injection valves, air

valves, etc… they may not show up until full expansion of the corresponding part has taken

place after the engine the has been in operation a longer time at normal load. No leaks of any

kind should be allowed, if they cannot be stopped while the engine is running the engine

should be stopped and not restarted until the trouble corrected.

RUNNING

In general the attention, which an operator must give to, the engine in regular operation is

along the same lines as during the warm-up period. The differences is that the corresponding

observations should be made periodically every 15 to 20 minutes and at least every half hour, even if

the engine is equipped with-a sufficient number of automatic danger-warming signal ad seconds, that

all observations must be entered in engine log.

THE ENTRANCES IN A COMPLETE ENGINE LOG ARE THE FOL LOWING:

1. Time of entering the readings, or rather the first reading in each series.

2. Engine load, or in the case of electric loads, volts and amperes reading.

3. Engine speed from the tachometer or if the engine has an adding revolution counter, the

counter reading, in this case it is essential to have in the engine room a large clock with a hand

indicating seconds, to enable the operator to read the revolution counter at exact intervals.

77

4. Fuel consumption enter the instantaneous reading of s rotameter or the reading of a fuel meter

in which case it is also important to make the reading at exact intervals.

5. Exhaust:

a.) Reading of the temperature of exhaust from each cylinder;

b.) Exhaust temperature in the exhaust line close to the exhaust manifold;

c.) Color of exhaust either by simple description such as clear, little haze, light gray, gray,

dark gray and very dark gray or better, by a number according to a standardized smoke

scale, such as Ringleman’s scale.

6. Lubricating oil:

a.) Pressure as discharged from the oil pressure pump.

b.) Temperature of the oil before the oil cooler.

c.) Temperature of the oil after the oil cooler.

7. Cooling water:

a.) Temperature of the water delivered to the water-cooling manifold.

b.) Temperature as discharge from each cylinder, or in the water outlet line.

c.) Flow, gallon per minute, either from the rotameter or a water meter.

8. Scavenge air:

a.) Temperature after blower

b.) Pressure after blower, usually in inches of mercury.

9. Super charger conditions:

a.) Temperature of air after booster pump.

b.) Pressure of the air after booster pump, Psi or inches of mercury.

10. Barometric pressure, inches of mercury.

11. Temperature of the air intake, before the air filter.

12. Remarks about what happened at e certain moment during operation of the engine, such as,

put second engine online or stopped it, found lubricating oil filter clogged by dirt as indicated by

excessive pressure drop, switched to the second filter, or by-passed filter and exchanged filter

element, etc. Between taking readings and entering them in the engine log, the operator

should listen to find out if the engine is running uniformly, without unusual sounds or knocks.

He should feel whether the bearing are running warmer than usual and particularly watch that

the engine as a whole doest not become overloaded or some of the cylinders become

78

overload. Because in the combustion in one or two cylinders doest not proceed correctly, as

indicated by a considerable lower or higher temperature from that exhaust particular cylinders.

Naturally, the operator must also see that the day fuel tank is not depleted and if the engine

has hand lubricated places that they are oiled at regular intervals. Should be oiled every two

hours the exhaust valve stems should receive a few drops of kerosene instead of oil every

three or four hours in order to keep them in good working condition. The circular groove

around the valves and the whole top of the cylinder head must be wiped clean at all times. Oil

must be allowed to accumulate on the cylinder head and run down the side of the engine, as it

could easily work into the joints between the cylinder and heads and decompose the rubber

gaskets with form the water joint.

If the flow of the cooling water or oil should stop for any reason, the engine or any of the

cylinder will become overheat. The engine must be stopped at once and permitted to cool

gradually. It is extremely dangerous to admit water to a hot engine as a sudden change in

temperature nay cause the pistons or one of the cylinder heads, liners or the exhaust manifold

to crack.

The exhaust from the engine should be perfectly clean. However, if the engine is

operating under an overload, the exhaust may become visible, with a light grayish smoke. If

the engine is visible under over than overload conditions, the cause should be found

immediately reminded. An engine under no condition is operated for any length of time with a

visible smoky exhaust.

If the pyrometer with thermocouples is installed on the engine cylinder that yields a

smoky exhaust may be found by nothing the exhaust temperatures of the various cylinders. If

abnormal condition exist in any of the cylinders, this condition will usually be accompanied by

an increase in the temperature of the exhaust from the cylinders, do not get their share of fuel,

and a result, the other cylinder are overloaded. If possible the engine should be stopped and

the cause rounds and reminded.

STOPPING THE ENGINE:

To stop the engine, proceed as follows: move the fuel pump controls to stop position

and shut the fuel supply valve.

79

The cooling water and piston cooling oil should be left running after the engine is shut

down until the outlet temperature are not more than 5 to 10 of higher than the inlet

temperature. This prevents local overheating which would cause scale deposits.

The jackets, if hard water used ad the engine is supplied with direct connect pumps, it

will be necessary to start the auxiliary pumps to cool the engine as indicated above.

If the engine is to be shut down for a considerable length of time the water jackets must

be completely drained so as to prevent rust and in cold weather also protect the jackets from

bursting if the watering the engine room should freeze. Naturally, all drops oiliest must be

stopped. All switches cut-out, and friction clutches put in neutral position.

80

SCHEDULE OF DIESEL ENGINE INSPECTION AND MAINTENENC E

Engine parts to be inspected Recommended Max. Time Operating Hrs . Months

Engine cylinders or liner and pistons 6000 9 Air-intake valves 3000 6 Exhaust valves 1500 3 Starting air valves 4000 6 Safety or relief valves 100 1 Air compressor cylinder and pistons 3000 6 Compressor valves; suction and discharge 1500 2 Scavenge-pump cylinder & piston or rotor 3000 6 Scavenge-pump suction and discharge 3000 6 Scavenge port and automatic valves 3000 6 Exhaust –gas flow regulators 2000 6 Exhaust muffler and ducts 6000 12 Main bearing and journals 6000 12 Outboard bearing 6000 12 Thrust bearing 6000 12 Crankpins and bearing 3000 6 Piston rings or crosshead pin & bearing 6000 12 Crosshead guides and shoes 6000 12 Compressor piston pin and bearing 3000 6 Vertical shaft bearing 4000 6 Camshaft bearing 4000 6 Camshaft drive 2000 2 Fuel pumps 4000 8 Fuel pumps drive 2000 3 Fuel nozzles or valves & fuel timing 500 1 Governor links, bearings, springs 4000 6 Governor drives 4000 6 Water or oil cooled pistons: pickling 3000 6 Bearing, ball and hinges joints 3000 6 Scale and sediment deposits 3000 6 Cylinder head and jackets 1000 2 Cooling passages in pistons 2000 4 Compressor head and jackets 3000 6

81

SCHEDULE OF ENGINE – EQUIPMENT INSPECTION

Equipment to be inspected and serviced

Recommended Max. Time Between inspection

Operating Hrs

Months

Fuel system Filters and strainers 200 1 Fuel booster and transfer pumps 2000 4 Auxiliary storage tanks 1000 3 Supply lines 1000 3 Heaters for heavy fuel oil lubricating system 3000 6 Lubricating-oil pumps, complete 3000 6 Lubricating pump drive 3000 6 Oil supply lines 1000 2 Oil strainers and filters 200 1 Oil tanks 2000 4 Oil coolers, tightness and scale deposit 3000 6 Pressure feed lubricants and check valves 3000 6 Crankcase sediment and surface 2000 4

Air intake system Air filters 3000 1 Air suction ducts 2000 3 Air intake silencers 2000 3 Air coolers 3000 4 Exhaust mufflers, sediment and tightness 2000 4

Pressure gauge-check with standard gauges Lubricating oil 3000 6 Cooling water 3000 6 Compressed air 3000 6

Exhaust gas pyrometer, check with standard Pyrometer lead wires, check insulation 3000 6

Pressure-relief valve Fuel oil 3000 6 Lubricating oil 3000 6 Compressed air 3000 6 Cooling water 3000 6

82

MAINTENANCE SCHEDULE OF COOLING FUEL AND AIR EQUIPM ENT

Equipment to be inspected and serviced Months between inspection Cooling tower

Clean, adjust and level troughs 2 Clean distribution rocks 1 Clean and inspect screen 1 Drain and clean basin 6 Copper sulfate treatment for algae 6 Spray pond, clean and adjust spray nozzles 1

Jacket-water heat exchangers Rescale and clean tubes 3 Inspect for leaks and seal them 3

Water wells Check state levels 6 Check dumping level 6 Check flow 6

Water pumps Check suction pressure with gauge 6 Check discharge pressure with gauge 6 Check delivery 6 Check power input to each pump 3 Check speed of pump 3 Pull and inspect pumps for wear 6 Check thrust bearings and clearance 6 Drain and renew bearing oil 4

Water piping Inspect for leaks 3 Clean and paint exposed pipes 12

Fuel oil storage tanks Drain off water 6 Inspect for leaks 6 Drain off and clean out 12 Clean and paint outside 12

Fuel-oil pumping Inspect for leaks 6 Clean and paint exposed pipes 12

Air compressor Drain and renew oil 3 Inspect valves and bearings 3 General overhaul 12

Air storage tanks Drain off water and oil 2 Hydrostatic safety test 12 Check pressure gauge 12

83

Hydroelectric Power Plant

In the generation of hydroelectric power, water is collected or stored at a higher elevation and led downward through large pipes or tunnels (penstocks) to a lower elevation; the difference in these two elevations is known as the head. At the end of its passage down the pipes, the falling

water causes turbines to rotate. The turbines in turn drive generators, which convert the turbines' mechanical energy into electricity. Transformers are then used to convert the

alternating voltage suitable for the generators to a higher voltage suitable for long-distance transmission. The structure that houses the turbines and generators, and into which the pipes or

penstocks feed, is called the powerhouse.

Hydroelectric power plants are usually located in dams that impound rivers, thereby raising the level of the water behind the dam and creating as high a head as is feasible. The potential power

that can be derived from a volume of water is directly proportional to the working head, so that a high-head installation requires a smaller volume of water than a low-head installation to produce an equal amount of power. In some dams, the powerhouse is constructed on one flank

of the dam, part of the dam being used as a spillway over which excess water is discharged in times of flood. Where the river flows in a narrow steep gorge, the powerhouse may be located

within the dam itself.

TERMS AND DEFINITION Reservoir - stores the water coming from the upper river or waterfalls.

Headwater - the water in the reservoir or upper pool. Spillway - a weir in the reservoir which discharges excess water so that the head of the plant will be maintained.

Dam - the concrete structure that encloses the reservoir to impound water. Silt Sluice - a chamber which collects the mud and through which the mud is discharged.

84

LHYh −=

Trash Rack - a screen which prevents the leaves, branches and other water contaminants to enter into the penstock.

Valve - opens or closes the entrance of the water into the penstock. Surge Chamber - a standpipe connected to the atmosphere and attached to the penstock so

that the water will be at atmospheric pressure.

Penstock - a channel or a large pipe that conducts the water from the reservoir to the turbine. Turbine - a device or a machine that converts the energy of the water to mechanical energy.

Generator - a device or a machine that converts mechanical energy of the turbine into electrical energy.

Draft Tube - a pipe that conducts the water from the turbine to the tailrace so that the turbine can be set above the tail water level. Tailrace - is the canal that is used to carry the water away from the plant.

Undershot wheel - water enters at the bottom of the wheel tangential to its periphery and impinges on the buckets or vanes.

Breast shot wheel - a wheel used for heads up to 16 ft, where water enters between the bottom and top of the wheel at an angle and is prevented from leaving the wheel by a breast wall on the side of the wheel.

Over shot wheel - a wheel used for high heads, where water enters the wheel at the top by being discharged from a flume.

Gross head - is the difference between the headwater and tail water elevation. Spiral case - it conducts the water around a reaction type turbine.

A. IMPULSE TYPE (Pelton type) headwater Dam or Reservoir Penstock Y - Gross head Turbine tailwater

85

headwater

tailwater

draft tube

Y = Gross head

Dam

Scroll case

Generator

Turbine inlet ZB

PB

B

2

B

2

BB

L

D4

A

A

QV

Zg2

VPh

HYh

π=

=

++γ

=

−=

B. REACTION TYPE (Francis Type) D - penstock diameter, m Y - Gross head, m

VB - velocity at inlet, m/sec A - area of penstock, m2 HL - head loss, m

ZB - turbine setting above tailwater level, m

86

2

B

2

BB

L

D4

A

A

QV

Zg2

VPh

HYh

π=

=

++γ

=

−=

2D4

πA =

KW000,60

TN2BP

π=

PUMP STORAGE HYDRO-ELECTRIC PLANT

FUNDAMENTAL EQUATIONS

1. Total dynamic head or Net effective head a. For an Impulse type h = Y - HL

Y - Gross head at plant Gross head - difference in elevation between head water level and tail water level. b. For a Reaction type where: PB - pressure at turbine inlet in KPa VB - velocity of water at penstock, m/sec 2. Discharge or Rate of Flow (Q) Q = AV m3/sec where: D - diameter of penstock 3. Water Power (WP) WP = Qγh KW 4. Brake Power (BP)

Upper Pool

Lower Pool

Pump

Motor- Generator

Turbine

87

metersgD2

fLVH

2

L =

( )RPM

h813.3

BPNNs

45

=

metersN

gh260D

πφ

=

where: T - brake torque N-m N - no. of RPM 5. Head loss f - Moody friction factor L - length of penstock 6. Turbine Efficiency (e) e = ehemev

e = BP x 100% WP where: eh - hydraulic efficiency em - mechanical efficiency ev - volumetric efficiency 7. Generator Efficiency (ηg) ηg = GP x 100% BP where: GP - electrical output of the generator, KW 8. Rotative Speed (N) N = 120f RPM n where: n - number of generator poles(usually divisible by 4) 9. Turbine Specific Speed

10. Wheel Diameter

EXAMPLE: A Francis turbine is installed with a vertical draft tube. The pressure gauge located at the penstock leading to the turbine casing reads 372.6 KPa and velocity of water at inlet is 6 m/sec. The discharge is 2.5 m3/sec. The hydraulic efficiency is 85%, and the overall efficiency is 82%. The top of the draft tube is 1.5 m below the centerline of the spiral casing, while the tailrace level is 2.5 m from the top of the draft tube. There is no velocity of whirl at the top or bottom of the draft tube and leakage losses are negligible. Calculate, a) the net effective head in meters b) the brake power in KW c) the plant output for a generator efficiency of 92%. d) the mechanical efficiency Given: PB = 372.6 KPa

88

Air

Compressor

Gas

Turbine

Combustor

HEAT ADDED

TURBINE WORK

Compressor Work

%e

))((.e.

eeee

KW .881(0.92)Output Generator

KW 0.82(1075)BP

KW ).)(.(.hQPower

m .).(

)(

.

.h

Zg

vPh

m

m

vhm

BBB

96

1855820

5810

881

107584381952

84348192

6

819

6372

22

2

==

===

====γ=

=++=

++γ

= vB = 6 m/sec Q = 2.5 m3/sec

eh = 855 e = 82%

ZB = 1.5 + 2.5 = 4 m 2. A pelton type turbine was installed 30 m below the head gate of the penstock. The head loss due to friction is 15% of the given elevation. The length of the penstock is 80 m and the coefficient of friction is 0.00093. Determine a) the diameter of the penstock in mm. (421.6 mm) b) the power output in KW (781.234 KW)

GAS TURBINE POWER PLANT

Basic components � Compressor � Combustor

� Gas turbine Ideal Cycle: Brayton Cycle

Processes 1 to 2 – Compression (S = C)

2 to 3 – Heat addition (P = C) 3 to 4 – Expansion (S = C)

4 to 1 – Heat Rejection (P = C) Schematic diagram of a Simple Open Gas turbine cycle

89

Closed Cycle Gas Turbine Cycle

The Air Standard Brayton Cycle

P

V

T

S

1

S = C

2 3

4

S = C

1

2

3

4 P = C

P = C

QA

QR

Air

Compressor

Gas

Turbine

Heater

HEAT ADDED (QA)

TURBINE WORK (Wt)

Compressor Work (Wc)

Cooler

HEAT REJECTED (QR)

1

2

3

4

90

4

3

1

2

P

P

P

PrP ==

4

3

1

2

T

T

T

T=

11 100% x T-T

T-T-1e

10 100% x Q

Q-Qe

9 100% x Q

We

23

14

A

RA

A

→

=

→=

→=

Compressor work (work done on the system, S = C)

Q = ∆h + ∆KE + ∆PE + W

∆KE & ∆PE are negligible

Q = 0 (for isentropic) -W = ∆h = Wc

WC = m(h2 – h1) = mCp(T2 – T1) → 1

Turbine Work (work done by the system, s = C))

+W = -∆h = Wt

Wt = -m(h4 – h3)

Wt = mCp(T3 – T4) → 2

Pressure Ratio

→ 3

From isentropic, P & T relationship

→ 4

Heat added (P = C) QA = mCp(T3 – T2) → 5

Heat rejected

QR = mCp(T4 – T1) → 6

Net cycle work

W = QA – QR → 7

W = mCp[(T3 – T2) – (T4 – T1)] → 8

Thermal Efficiency

91

% 100 x Work compressor Actual

Work Compressor IdealC =η

% 100 x Work Turbine Ideal

Work Turbine ActualT =η

% 100 x Fuel by Supplied Heat

air by Absorbed Heatk =η

Compressor Efficiency

Turbine Efficiency

Combustor Efficiency

Example: A small open cycle gas turbine power plant produces a net power output of 600 KW

while operating under the following conditions; the inlet air pressure and temperature 100 KPa and 300 K, respectively; the pressure ratio is 10. The combustor uses C12H26

and has an air-fuel ratio of 67 kg of air per kg fuel. The fuel HV = 44,102 KJ/kg; the combustion products leaves the combustor and enters the turbine with h = 1241.3 KJ/kg

and exit the turbine with h = 662.5 KJ/kg. Calculate: a. The air flow rate

b. The compressor power in KW c. The turbine power in KW

d. The thermal efficiency of the plant

Air

Compressor

Gas

Turbine

Combustor

QA

WT Wc

ma

ma

mg

mg

1

2 3

4

92

( )

KW .).(.,W

KW ..03)18,780.1(0W

kg/sec .67(0.03)m

45.3% 100% x 1323.06

600e

KW .2)0.03(44,10Q

kg/hr kg/sec .m

m.,

m.,m.,

WWW

6 m.,W

662.5)-(1241.368m)h-(hmW

turbine gas the in balance energy By

5 (44,102)m(HV)mQ

4 m.,67(280.3)mWc

3 68mm67mm

2 mm

m

m

mmm

1 m.))(.(mWc

KT

P

P

T

T

)TT(Cm)hh(mWc

t

c

a

A

F

F

FF

ct

Ft

F43gt

FFA

FF

FFFg

Fa

F

a

Fag

aa

.

.

k

k

paa

81180030435839

4563

012

061323

108030

357620600

178018435839600

435839

178018

67

67

328030057900451

57910300 41

141

2

1

1

2

1

2

1212

====

==

==

====

=−=

−=→=

==

→==→==

→=+=→=

=

+=→=−=

°==

=

−=−=

−

−

93

2000

vAP

Avm

equation continuity From

)(

vmP

3

itotal

iTotal

ρ=

ρ=

=10002

2

WIND POWER

Wind Energy, energy contained in the force of the winds blowing across the earth’s surface. When harnessed, wind energy can be converted into mechanical energy for

performing work such as pumping water, grinding grain, and milling lumber. By connecting a spinning rotor (an assembly of blades attached to a hub) to an electric generator, modern wind turbines convert wind energy, which turns the rotor, into electrical energy.

Total Power The total power of a wind stream is equal to the rate of the incoming kinetic energy of

that air stream, KEi,

94

)(

)vv)(vv(AP

vvv

)(

vvAvP

eieiMax

ei

eiMax

10004

2

10002

22

22

−+ρ=

+=

−ρ=

3

22

2 i

eiei

Total

Max

v

)vv)(vv(

100% x P

P

−+=η

=η

Where: Ptotal = total power , KW m – mass flow rate in kg/sec vi – incoming velocity, m/sec

ρ - incoming density, kg/m3

A – cross sectional area of stream, m2 Maximum Power

Where: ve- exit velocity of stream, m/sec

Maximum Efficiency (Ideal theoretical Efficiency)

Power plant technology (lecture notes)

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