Exergy Analysis Of Steam Power Plant For Different Grades Of Coal

A Project report On

EXERGY ANALYSIS OF STEAM POWER PLANT FOR DIFFERENT GRADES OF COAL Submitted in partial fulfillment of the requirement of

National Institute Of Technology , Raipur For

The Bachelor of Technology In

MECHANICAL ENGINEERING

Approved by Mr. S.Sanyal

Guided by Mr. S. D. Patle

Prof. & HOD,

Associate Professor

Mech. Engg. Department

Mech.Engg.Department Mech.Engg.Departm ent Submitted by

DEPARTMENT OF MECHANICAL ENGINEERING NATIONAL INSTITUTE OF TECHNOLOGY,RAIPUR

CERTIFICATE EXERGY ANALYSIS OF STEAM This is to certify that the project work titled submitted by Sumit Singh POWER PLANT FOR DIFFERENT GRADES OF COAL (08119079) , Manish Jain(08119039), Manish churendra (08119038) Aditya Gandharla (08119005), Lucky Jethani (08119037), Vikram Singh(08119067) Kamlesh Sahu(08119032), Poshak Chaudhary(08119049) students of o f B.Tech B. Tech final Year of mechanical engineering during the academic year 2011-12 in partial fulfillment of the requirements for the award of the degree of bachelor of technology in mechanical engineering by National Institute of Technology, Raipur is a presentation of work done by them. This certification does not necessarily endorse or accept any statement made, opinion expressed or conclusion drawn as recorded in the report. However, it only signifies the acceptance of the report for the purpose for which it is submitted.

Approved by:

Guided by:

Dr. S.Sanyal

Dr.S.D Patle

Professor & Head

Associate Professor,

Deptt. of Mechanical engg.

Deptt. of Mechanical engg.

2

DECLARATION BY CANDIDATES

I the undersigned solemnly declare that the thesis entitled“ EXERGY ANALYSIS POWER PLANT

OF STEAM

own research research work carrie carried d ou t FOR DIFFERENT GRADES OF COAL”is my own

under the supervision of Dr.S.D.Patle,department of mechanical engineering , National institute of technology Raipur (C.G) ,India. I further declare that to the best of my knowledge and belief the thesis does not contain any part of any work which has been submitted for the award of any other degree or certificate either this institute or any other university/deemed university/deemed university of India or any other country.

The Guide Dr. S.D.Patle

Associate professor Department of mechanical engineering National institute of technology Raipur (C.G)

3

-Candidates

ACKNOWLEDGEMENT Completing a task is never a single person’s effort.It is always the result of valuable contribution of a group of individuals that helps in shaping & achieving the objective. We express our heartfull thanks to those who have contributed greatly in accomplishing this task. We express our deep sense of gratitude to Mechanical

engg.

Dr.S.D. Patle, Associate

Professor

Deptt. Who has the attitude & substance of genius for his whole hearted

cooperation , valuable guidance, encouragement & suggestions throughout this project work which were of immense help in successfully completion of this work. We also take this opportunity to convey our deep gratitude to Dr.S.Sanyal,Professor & Head of Mechanical Engg. Deptt., for his words of inspiration & encouragement and kind approval of the work.

4

ABSTRACT This work is based on the application of second law of thermodynamics for e nergy efficient design and operation of the conventional coal fired power generating station.the steam power plant has been used for the analysis at present working con dition. The energy assessment must be made through the energy quantity as well as the quality .but the usual energy analysis evaluates the energy generally on its quantity only. However ,the exergy analysis assesses the energy on quantity as well as the quality . the primary objectives of this project are to analyze the system components separately to identify and quantify the sites having largest energy and exergy losses .in addition ,the effect of varying the reference environment state on this analysis will also be presented the aim of the exergy analysis is to identify the magnitudes and the locations of real energy losses to improve the existing systems processes or components .This project deals with an energy and exergy analysis performed on an operating 250MW unit of NTPC-SAIL power company limited ,Bhilai 3,(CG) India. The exergy losses occurred in the various subsystems of the plant and their components have been calculated using the mass ,energy and exergy balance equations. The distribution of the exergy losses in several plant components during the real time plant running conditions has been assessed to locate the process irreversibility. The first law efficiency and the second law efficiency of the plant have also been calculated .the comparison between the energy losses and exergy losses of the individual components of the plants shows that maximum energy losses in present working condition occurred in the boiler. The real losses of energy which has scope for the improvement are given as maximum exergy losses that occurred in the combustor in boiler subsystem . The results of the exergy analysis indicate that the boiler produces the highest exergy destruction.

5

TABLE OF CONTENTS Certificate

2

Declaration by the candidates

3

Abstract

4

Acknowledgement

5

Table of contents

6

List of figures

10

List of tables

12

Nomenclature

13

Subscript

14

Chapter 1 Introduction

1.1

Energy

15

1.1.1

The steady flow process

15

1.1.2

Energy efficieny of steady flow devices

16

1.2

Exergy

17

1.2.1

Definition of exergy

18

1.2.2

Exergy destruction

18

1.2.3

Mode of exergy transfer

19

6

1.2.3.1

Exergy transfer by work

19

1.2.3.2

Exergy transfer by heat

20

1.2.4

Exergy transfer by mass

20

1.2.4.1

Physical Exergy

20

1.2.4.2.

Exergy of kinetic energy

21

1.2.4.3.

Exergy of potential energy

21

1.3

Exergy balance of a steady flow system

22

1.3.1

Exergy efficiency of steady flow device

1.4

Dead state

24

1.5

Exergy associated with fuel (coal) and flue gases

24

1.6

Power scenario in india

25

1.7

Objective of the study

26

23

Chapter2 Combustion calculation

2.1

Introduction

27

2.2

Calculation of chemical exergy of fuel

30

Chapter 3 problem formulation and plant description

3.1

Problem formulation

33

3.2

Data of different grades of coal

34

3.3

Power plant description and specification

35

3.3.1

Air fan

35

7

3.3.2

Air preheater

36

3.3.3

Boiler

37

3.3.4

Turbine

38

3.3.5

Deaerator

39

3.3.6

Condenser

41

Chapter4 Exergy analysis of components in the power plants

4.1

Boiler

44

4.2

Steam turbine

45

4.3

Air fan

46

4.4

Air preheater

47

4.5

Condenser

48

4.6

Feed water heater1

49

4.7

Deaerator

50

4.8

Condenser pump P1

51

4.9

Circulation pump

52

Chapter 5 Result and discussion

5.1

Analysis with a full load operation condition

53

5.2

Analysis of steam generator(boiler)

56

5.2.1

Effect of surrounding temperature on exergetic efficiency of the boiler

58

5.3

Analysis of turbine

59

5.3.1

Turbine efficiency variation with temperature

8

60

5.4

Study of performance of boiler and air preheater with the usage of different grades of coal in the power plant

60

Chapter6 C++ Programme coding for some iterative calculation 6.1

C++ programme coding for combustion calculation

71

6.2

C++ programme for calculation of chemical exergy of fuel

73

9

LIST OF FIGURES

Fig1.1

An Open system

Fig1.2

Total installed power generation capacity of india

Fig2.1

Combustion calculation of the fuel

Fig2.2

Calculation of chemical exergy of fuel

Fig3.1

Schematic diagram of the power plant

Fig3.2

The ideal rankine cycle(T s digram)

Fig3.3

Air fan

Fig 3.4

Air preheater

Fig 3.5

Boiler

Fig 3.6

Turbine

Fig 3.7

Deaerator

Fig4.1

Boiler

Fig 4.2

Turbine

Fig 4.3

Air fan

Fig 4.4

Air preheater

Fig 4.5

Condenser

Fig 4.6

Feed water heater

Fig4.7

Deaerator

Fig 4.8

Condenser pump P1

Fig4.9

Circulation pump

Fig 5.1

Graphical representation of exergetic efficiency of different units of the power plant

10

Fig5.2

Pie chart for exergy destruction in various components of the power plant.

Fig 5.3

Thermal and exergetic efficiency comparis

Fig5.4 Graphical representation of the variation of boiler exergetic efficiency with a variation

in

reference temperature Fig5.5

Fig 5.6

Graphical comparison of the thermal and exergetic efficiency of the turbine

Graphical representation of the variation of exergetic efficiency with variation in reference temperature.

Fig5.7

Graphical representation of boiler efficiency v/s calorific value of coal

Fig 5.6

Graphical representation of air preheater exergetic efficiency v/s calorific value of coal

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LIST OF TABLES

Table 3.1: Operating conditions of the power plant . Table 3.2

Grades of coal

Table 3.3

Composition of designed coal

Table 5.1

Exergy efficiency and exergy destruction calculation

Table 5.2

Boiler efficiency variation with temperature

Table 5.3

Exergy destruction and exergetic efficiency at different reference temperatures in the turbine

Table5.4

Exergy destruction and exergetic efficiency of the boiler for different grades of coal.

Table5.5

Exergy destruction and exergetic efficiency of air preheater for different coal grades

Table 5.6

Exergy analysis for temperature (To)=298k.

Table 5.7


Table 5.8


Table 5.9


Table 5.10 Exergy analysis for temperature (To)=303k.

Table 5.11

12

Composition of grades of coal used for analysis in the project

NOMENCLATURE

C

Carbon [%]

C p

Specific heat [kJ/kg K]

e

Specific exergy [kJ/kg]

E

Time rate of exergy [MW]

FWH

Feed Water Heater

I

Energy efficiency [%]

II

Exergy efficiency [%]

h

Specific enthalpy [kJ/kg]

LHV

Lower heating value [kJ/kg] Time rate of mass [kg/s]

n

Excess air

N

Nitrogen [%]

O

Oxygen [%]

P

Pressure [kPa]

Q

Time rate of heat loss [MW]

S

Sulphur [%]

s

Specific entropy [kJ/kg]

T

Temperature [ºC]

W

.

W

13

Time rate of work [MW] Water [%]

SUBSCRIPT

a

Air

B

Boiler

CH

Chemical

CV

Control volume

D

Destruction

DG

Dry gas

ECO

Economizer

EVA

Evaporator

G

Combustion gas

i

Inlet

KN

Kinetic

o

Outlet

P

Product

PH

Physical

PT

Potential

R.H

Re-heater

S.H

Super-heater

ST

Steam turbine

th

Theoretic

WG

Wet gas

14

CHAPTER 1 INTRODUCTION 1.1 ENERGY

The concept of energy was first introduced in mechanics by newton when he hypothesized about kinetic and potential energies .however the emergence of energy as unifying concepts in physics was th

not adopted until the middle of 19

Century and was considered one of the major scientific achievements in that century .The concept of energy is so familiar to us today that it is intuitively obvious ,yet we have difficulty in defining it exactly . Energy is a scalar quantity that can not be observed directly but can be recorded and evaluat4ed by indirect measurements .The absolute value of energy of system is difficult to measure , whereas its energy change is rather easy to calculate .In our life the example for energy are endless. The sun is the major source of the earth’s energy .It emits a spectrum of energy that travels across space as electromagnetic radiation. Energy is also associated with the structure of matter and can be released by chemical and atomic reactions .Through out history ,the emergence of civilization has been characterized by the discovery and effective application of energy to society’s needs. One of the most fundamental law of nature is the conservation of energy principle . It simply state that during an interaction ,energy can change from one form to another but the total amount of energy remains constant. That is , energy can not be created or destroyed. 1.1.1The steady -flow process

The terms steady and uniform are used frequently in engineering , and thus it is important to have a clear understanding of their meanings. The terms steady implies no change with time .The term uniform ,however implies no change with location over a specified region .A large number of engineering devices operate for long periods of time under the same conditions , and they are classified as steady flow devices. Process involving such devices can be represented reasonably well by a somewhat idealized process ,called a steady flow process.

15

Assumptions:

The following assumptions are made in the system analysis: 

The mass flow through the system remain constant.



Fluid is uniform in composition.



The only interaction between the system and surrounding are work and heat.



The state of fluid at any point remain constant with time.

The steady flow equation (u1+p1v1+V12 /2 +gZ1)+δQ/δm = (u2+p2v2+V22 /2 +gZ2)+ δw/δm

1.1

The steady flow energy equation m[u1+p1v1+V12 /2 +gZ1]+Q =m [u2+p2v2+V22 /2 +gZ2]+ W

1.2

where; m;mass (kg/sec) u1 and u2; Internal energy at inlet and outlet(kj/kg) V1 and V2; velocities of fluid at inlet and outlet (m/sec) Z1 and Z2 ; elevation at inlet and outlet(metre) Q; heat transfer rate at inlet and outlet(kwatt) W;work transfer rate at inlet and outlet(kwatt)

1.1.2Energy efficiency of steady flow devices

Efficiency is one of the most frequently used terms in thermodynamics , and it indicates ,how well an energy conversion or transfer process is accomplished . Efficiency is also one of the most frequently misused term in thermodynamics and a source of misunderstanding . The performance or efficiency, in general, can be expressed in terms of desired output and the required input. Efficiency = Desired output/Required input

16

1.3

1.2EXERGY

Exergy analysis has sparked interest in the scientific community to take a closer look at the energy conversation devices and to develop new techniques to better utilize the existing limited resources. First law of

thermodynamics deal with the quantity of energy and asserts that energy cannot be

created or destroyed .This law merely serves as a necessary tool for the bookkeeping of energy during a process and offers no challenges to the engineer. The second law, however, deals with the quality of energy. More specifically, it is concerned with the degradation of energy during a process , the entropy generation , and the lost opportunities to do work. The second law of thermodynamics has proved to be a very powerful tool in the optimization of complex thermodynamic systems . we examine the performance of engineering devices in light of the second law of thermodynamics. we start our discussion with the introduction of exergy (also called availability)which is the maximum useful work that could be obtained from the system at a given state in a specified environment ,and we continue with the reversible work, which is the maximum useful work that can be obtained as a system undergoes a process between two specified state . Next we discuss the irreversibility (also called the exergy destruction or lost work),which is the wasted work potential during a process as a result of irreversibilities , and be defined as second law efficiency .We then develop the exergy balance relation and apply to closed systems and control volumes.

When a new energy source, such as geothermal well ,is discovered ,the first thing the explorers do is estimate the amount of energy contained in the source .This information alone, however ,is of little value in deciding whether to build a power plant on that site .what we really need to know is the work potential of the source-that is ,the amount of energy we can extract as useful work .T he rest of the energy will eventually be discarded as waste energy and is not worthy of our consideration .Thus ,it would be very desirable to have a property to enable us to determine the useful work potential of a given amount of energy at some specified state.

This property is Exergy ,which is also called the availability or available energy. The

work

potential of the energy contained in a system at a specified state is simply the maximum useful work that can be obtained from the system. You will recall that the work done during a process depends on the initial state, the final state, and the process path. That is,

17

Work = f (initial state, process path, final state)

Despite the rapid developments in renewable energy utilization, it can be estimated that, fossil fuel dependency will continue for decades. Lignite is one of the most widely used fossil fuels in Turkey due to its vast reserves. According to IEA, approximately 65% of the total energy demand is met by coal in India. However, because of the environmental effects and combustion difficulties of the low grade lignite, an improved method for its better utilization is required. As a result, pre-treatment of coal is widely used for lowering the combustion emissions.

The aim of this study is to study a coal based thermal power plant and perform an exergy analysis based on the second law of thermodynamics to evaluate the exergetic efficiency and exergy destruction of the overall plant and each of its components, and to identify the extent and exact location of the exergy destruction in the system. Finally, the power plant is modeled assuming various types of coal that are currently employed in real thermal power plants. The results are compared in terms of energy generation, exergetic efficiency and CO2 emissions for each type of coal.

1.2.1Definition of exergy

It is the maximum possible useful work that could be obtained from the system at a given state in specified environment. The work potential of the energy contained in a system at a specified state is simply the maximum useful work that can be obtained from the system.Work output is maximized when the process between two specified states is executed in a reversible manner, as therefore, all the irreversibilities are disregarded in determining the work potential. 1.2.2Exergy destruction

Irreversibilities such as friction , mixing, chemical reaction, heat transfer through a finite temperature difference, unrestrained expansion, non quasieqilibrium compression or expantion always generate entropy and anything that generate entropy always destroys exergy.The exergy destroyed is proportional to the entropy ge nerated , it is expressed as Xdestroyed = (T0S) >0

1.4

Note that exergy destroyed is a positive quantity for any actual process and becomes zero for reversible process. Exergy destroy represent the lost work potential and is also called the irreversibility or lost work for the decrease of exergy and the exergy destruction is applicable to any

18

kind of system undergoing any kind of process since any system and its surroundings can be enclosed by a sufficiently large arbitrary boundary across which there is no heat, work and mass transfer, and thus, any system and its surrounding constitute an isolated system. No actual process is truly reversible and thus, some exergy is destroyed during a process .Therefore, the exergy of the universe which can be considered to be an isolated system is continuously decreasing. The more irreversible a process is , the larger the exergy destruction during that process. No exergy is destroyed during a reversible process. 1.5

Xdestroyed =0

The decease of exergy principle does not imply that the exergy of system can not increase. The exergy change of a system can be positive or negative during a process but the exergy destroyed can not be negative. 1.6

Xdestroyed, impossible <0

1.2.3Mode of exergy transfer 1.2.3.1Exergy transfer by work

Exergy is the useful work potential ,and the exergy transfer by work can simply be expressed as:Xwork =W-Wsurr

for boundary work

1.7

Xwork =W

for other form of work

1.8

Where Wsurr =P0(V2-V1) P0 is atmospheric pressure,and V1 and V2 are the initial and final volumes of the system

Therefore,the exergy transfer with work such as shaft work and electrical work is equal to the work W itself.in the case of a system that involves boundary work,such as piston cylinder devise ,the work done to push the atmospheric air out of the way during expansion can not be transferred, and thus it must be subtracted .also, during a compression process , part of the work is done by the atmospheric air,thus we need to supply less useful work from a external source .

19

The work done by or against the atmospheric pressure has significance only for system whose volume changes during the process.it has no significance for cyclic devices and system whose boundary remain fixed during a process such as steady flow devices like turbine and heat exchanger etc.

1.2.3.2Exergy transfer by heat

The work potential of the energy transfer form a heat source a temperature T is the maximum work that can be obtained from that energy in a environment at temperature T0 and is equivalent to the work produced by a carnot heat engine operating between the source and the environment therefore,the carnot efficiency represents as:c=(1-T0/T)

1.9

Therefore , heat transfer is always accompanied by exergy transfer.heat transfer Q at a location at thermodynamic temperature T is always accompanied by exergy transfer Xheat is in the amount of

Xheat=(1- T0/T)Q

1.10

Where T0 =environment temperature T=system temperature Q=heat added or heat rejected

1.2.4Exergy transfer by mass 1.2.4.1Physical Exergy

It can be calculated :Xph=(h-h0)-T0(S-S0)

Where hand h0 are specific enthalpy at temperature Tand T0 respectively S andS0 are specific entropy at temperature Tand T0 respectively X ph is the physical exergy per unit mass

20

1.11

1.2.4.2. Exergy of kinetic energy

It is:2

Xke=KE=V /2

1.12

Where V is the velocity of the system related to the environment KE is the kinetic energy. Xke=total Exergy of kinetic energy per unit mass

1.2.4.3.Exergy of potential energy

It is:Xpe=PE=gZ

1.13

Where g is the gravitational acceleration. Z is the elevation of the system related to reference level in the environment . PE is the potential energy. X pe is the exergy of potential energy per unit mass. There for ,the exergies of kinetic and potential energies are equal to themselves ,and they are entirely available for work

21

1.3Exergy balance of a steady flow system

Fig.1.1 An Open system

Let us consider , a steady state , control volume system .

Mass balance:

1 =

2 =

Energy balance:

(u1+p1v1+V12 /2 +gZ1)+ δQ/δm = (u2+p2v2+V22/2 +gZ2)+ δw/δm

1.14

Exergy balance:

Af1+δQ/δm(1-T0/T) = Af2 +δw/δm - dI/dm

1.15

Af1 +Ati = Af2 +Ato – T0(dσ/dm)

1.16

Specific flow availability, Af = h – T0S + V2/2 +gZ

1.17

22

Entropy balance :

∆Ssystem

+ ∆Ssurrounding =

∆Suniverse

( Entropy generation)

S2 – S1 – 1/TH (δQ/δm) = dσ/dm S2 = S1 +1/TH (δQ/δm) + dσ/dm

Entropy flowing = Entropy flowing + Entropy flow Out

in

+ Entropy generation

from surroundings

1.3.1 Exergy efficiency of steady flow device

FIRST LAW EFFICIENCY:

I

=

Net power generatedby powerplant Rate of energy released in the boiler bycombustion of fuel

SECOND LAW EFFICIENCY: it is the ratio of the actual thermal efficiency (

possible (reversible ) thermal efficiency(

rev

rev).

Reversiblepower generatedby powerplant =

Rate of energy released in the boiler bycombustion of fuel.

Therefore, II=

I/

rev

In other words, II=Wu/Wrev,(work producing devices). II= Wrev/

23

Wu,(work consuming devices).

i

)to the maximum

1.4 Dead state

Possibility of a doing work decreases as the state of system shifts towards that of the environment and ceases if the two are in equilibrium with one another .this state of system is known as dead state. 1.5 Exergy associated with fuel (coal) and flue gases Dulonge formula

HHV= 33.83C  144.45(H



O

8

)  9.38S MJ/kg

LHV=HHV-2.395mw MJ/kg is the fuel specific exergy, and the exergy factor based on the lower heating value (β )

24

1.6 Power scenario in india

Fig1.2 total installed power generation capacity of india

1. mentioned earlier, coal constitutes the most dominant constituent of the energy sector. In the year 2005-06, the coal production was over 370 million tones. Power Sector consumes almost 80% of coal that is produced. India has large coal reserves of the order of 200 Billion Tones, most of these are high ash content coal in the calorific value range of 3000 kilo calorie per kilogram to 4,500 kilo calorie per kilogram and ash content in the range of 30 – 45%. Using the high ash coal for the power sector is a major challenge, from the point of view of achieving high level of efficiency of consumption, and more particularly, from the point of view of environmental management due to fly ash emissions.

2.So far as the institutional framework is concerned, coal industry is pre-dominantly managed through a number of coal companies directly under the control of Government of India. Though the practice of allotting coal blocks for captive purposes to the private sector has been there for quite some time, it is only in the recent past, in the last 2 years particularly, a number of coal blocks have

25

been allotted and are being allotted to both public sector power companies and private sector power plants. The results of these decisions would be forthcoming in next 2-3 years when one could expect that a reasonable amount of coal production would be taking place through organizations other than the state controlled coal companies.

1.7Objective of the study

The results of the major project will mention: 1)

Develop a model to carry out detailed energy and exergy analysis of a steam power plant

under steady operating condition. 2)

Identify systems that have potential for significant improvement

3)

Formulate performance parameters for individual systems of the steam power plant

appropriate to its desired output and necessary input to the process . 4)

Implement the concept of exergy utilization , exergy balance and exergy conservation for

steam power plant. 5)

To suggest appropriate operating condition and other measures for improvement in

performance of the steam power plant. 6)

To calculate exergetic efficiency for each component of the power plant.

7) All iterative calculations for exergy analysis will be done by framing programs. Hence, the programs framed and used in the major project will also be a part of the final report.

26

C/C++

CHAPTER 2 COMBUSTION CALCULATION 2.1 Introduction

Combustion is an exothermic high temperature oxidation process of combustible elements of fuel with air. To obtain complete combustion, four major requirements must be fulfilled which are temperature, time,turbulence and sufficient oxygen. To calculate the combustion gas temperature at different points of the stream and overall plant emissions, air and gas flow rates must be evaluated. Specific oxygen requirement, which can be calculated with the elemental analysis of coal, is given in Eq. 3. Secondly, the specific air requirement is proportional to the volume percentage of O2 in the air and it is assumed as 0.21 for the calculations. To obtain complete combustion, excess air is provided to the combustion chamber and in the analysis excess air is assumed as 10%.

Combustion calculations have been made using following formulae and expressions:

Minimum oxygen required O2min=1.87C+5.6(H-O)+0.7S

2.1

Theoretical air required Va(th)=(1/0.21).O2min

2.2

Actual air required Va=nVa(th)

2.3

The amount of specific dry gas in combustion can be found by: VDG(TH)=VCO2+VSO2+Vn(fuel)+Vn(air)

2.4

Volume of CO2 present in combustion gas VCO2=1.87C

27

2.5

Volume of SO2 present in combustion gas VSO2=0.7S

2.6

Volume of nitrogen present in combustion gas V N(air)=3.76O2min

2.7

V N(fuel)=0.8N

2.8

Volume of moisture in combustion gas VH2O=1.244(W+9H)

2.9

Theoretical wet gas volume VWG(TH)=VDG(TH)+VH2O

2.10

Actual wet gas volume VWG=V WG(Th)+(n-1)Va(th)

2.11

Total air requirement Va=mfuel.Va

2.12

Total wet gas volume VG=m.VWG

28

2.13

sample c++ programme output for combustion calculation using formulae mentioned above:-

Fig2.1 combustion calculation of the fuel

29

2.2Calculation of chemical exergy of fuel

eCH(fuel)=β.(LHV) eCH(fuel) is the fuel specific exergy and the exergy factor based on the lower heating value(β) is:β=1.0437+0.1882(h/c)+ 0.0610(o/c)+0.0404(n/c) h= hydrogen content c= carbon content o = oxygen content n= nitrogen content

sample c++ programme output for calculation of chemical exergy

Fig. 2.2 calculation of chemical exergy of fuel

30

CHAPTER3 Problem formulation and plant description

Study of the schematic of the power plant is necessary before we begin exergy analysis of the plant. The following diagram shows a scheme of the power plant with the important component that ve been analyzed in this project .the streams that have been numbered are useful for study of this project. The important parameter like temperature , pressure ,mass flow of the nu mbered streams have been obtained for calculation of this project. The shown schematic is for a 250 MW unit of a power plant.

Fig3.1 schematic diagram of the power plant

31

TABLE 3.1: Operating conditions of the power plant. Operating condition

Value

Turbine power output

250 MW

Main steam pressure

147.10 bar

Main steam temperature

540 0C

Main steam flow rate

790.0 tonnes/hour

Reheat steam pressure

38 bar

Reheat temperature

540 0C

Reheat steam flow rate

682.62tonnes/hour

Condenser pressure

0.0932 bar

Low pressure pre-heater number

4

High pressure pre-heater number

2

Boiler efficiency

86.38%

32

3.1 Problem formulation

1.to evaluate the thermal and exergetivc efficiencies for the steam power plant

2.boiler is the location where most of the exergy destruction in the plant takes place and needs maximum attention on its operation for optimum use of available energy of the fuel

3. calculation of heat input to the plant , boiler,heat rejection in the condencer ,heat exchange in the pre water heater ,turbine work, pump work ,heat rate and steam rate of the entire power plant

4.calculation of irrevercsibility for each component in the plant and effect of reference temperature.

Fig3.2The ideal rankine cycle(T s digram)

33

3.2 Data of different grades of coal Table3.2 Grades of coal

Useful Heat Value Grade

Corresponding

(UHV) (Kcal/Kg)

Gross Calorific Value GCV (Kcal/ Kg)

Ash% + Moisture % UHV= 8900-138(A+M)

(at 5% moisture level) O

at (60% RH & 40 C)

A

Exceeding 6200

Not exceeding 19.5

Exceeding 6454

B

Exceeding 5600 but not

19.6 to 23.8


exceeding 6200 C


exceeding 6454 23.9 to 28.6

exceeding 5600 D


exceeding. 6049 28.7 to 34.0

exceeding 4940 E



34.1 to 40.0

Exceeding 1300 but not exceeding 2400

34


40.1 to 47.0

exceeding 3360 G

Exceeding 5089 but not Exceeding 5597

exceeding 4200 F


Exceeding 3865 but not exceeding. 4324

47.1 to 55.0


Table3.3 Composition of designed coal

3.3 Power plant description and specification 3.3.1Air fan

Fig3.3 Air fan

Forced draught fans are installed at the inlet to the air pre heater and so they handle cold air. Power input is given by:

35

Mf (A/F)×v×dp/

fd

Where Mf is the mass flow rate of the fuel(kg/sec) A/F is the air-fuel ratio v is the specific volume of inlet air(m3/kg) Δp is the pressure developed by fanto overcome resistance in flow path and fd

is the overall efficiency of the FD fan

Specification: Type

:

AP1- 18/11 ( AP – Axial profile fan, 1)

Number of stage

:

18

Tip dia of impeller in decimeter

: 11

Hub dia ofimpeller in decimeter ) No. per Boiler

:

Two

3.3.2Air preheater:

Fig 3.4 Air preheater

36

The function of the air preheater is to preheat the air before entering the furnace utilizing some of the energy left in the flue gases before exhausting them to the atmosphere.Preheating the air saves fuel that would otherwise otherwise be used for that heating. heating.

Specifications: Make

:

BHEL

Type

:

Ljungstrom Trisector (Regenerative)

Air heater heater size size

:

27.5 VI-80-TM 2000 (2300)

No. of Air Preheater

:

2 per Boiler

Total Heating Surface per Air Heater

:

20280 m2

3.3.3Boiler:

Fig 3.5 Boiler

37

Function of a boiler is to generate steam at a desired temperature and pressure by transfering heat produced by burning fuel in a furnace, to water to change it into steam. According to ASME Code , a boiler is defined as : A combination of apparatus for producing , furnishing or recovering heat together with the apparatus for transforming the heat so made available to water which could be heated , vapourised and superheated to steam form.

Specification Manufacturer

: M/s. BHEL (C.E.Design.)

Type

:Natural circulation,

Water tube,

Tangential firing,

Dry, Radiant Reheat, Single drum, Top Supported, Bare tube Economiser, Balanced draft furnace. Type of Firing

: Tilting Tangential.

Minimum load at which steam generator : 30% can be operated continuously co ntinuously with complete flame, stability without oil support (%MCR)

3.3.4Turbine:

Fig 3.6 Turbine

38

Steam turbine is the most important prime mover for generating electricity.This falls under the category of power producing turbo machines. In a turbine, the energy level of the working fluid goes on decreasing along the flow stream. The purpose of turbine is to extract the maximum quantity of energy from the working fluid , to convert it into useful work with maximum efficiency.

Construction Three cylinder reheat condensing turbine Single flow HP Turbine with 24 reaction stages

: Make: BHEL, Tiruchy

Single flow IP Turbine with 16 reaction stages


Double flow LP Turbine with 8 reaction stages per flow

: Make: BHEL Tiruchy

2 Main Stop and Control valves


2 Reheat Stop and Control valves


1 Swing Check valve in Cold Reheat line

:Make: BHEL, Tiruchy

2 Bypass Stop and Control valves

: Make: CCI , Switzerland

3.3.5Deaerator:

Fig 3.7 Deaerator

39

There are corrosive effects of water which contain oxygen dissolved from the atmosphere and thus produces detrimental effects on the boiler tubes , steam pipes and other items of the plant. Therefore, one requirement of a modern feed water system is that ,it must supply water which h as an almost zero oxygen content, to the feed pumps for feeding the boiler. In a deaerator the deaeration and heating is carried out in two domes fitted to the storage tank.The bled steam is allowed to enter the storage tank above the water level from the top and flows along the steam space in the storage tank upto the deaerating domes.As the condensate enters, it passes through sprayers in parallel into the dome.The condensate is heated by the bled steam and the dissolved gases in the fluid leave the solution on heating by steam.Approximately 95% of the heating and deaeration takes place in the spray stage of the deaerator.

Specifications: Type

: Horizontal spray cum Tray type

Design Pressure (ata)

: 8 & FV

Hydrotest Pressure (ata)

:10.4

Storage tank Design Temperatuer : 250ºC Heater design temperature

: 350ºC

Hydrotest temperature

: Ambient

Operating Pressure (ata)

:6.04

Operating Temperature ºC

: 158.3 ºC

No. of trays

: 280

No Of Spray nozzle

: 52

Feed water heaters:

There are two types of feed water heaters:1)

Direct contact heater

2)

Indirect contact heater .

Basically these are heat exchangers.The thermal performance of feed water heater accessed by the difference in temperature between the water leaving the heater and the saturation temperature corresponding to the heater steam pressure.

40

Direct contact heater - In this type of heater ,there is direct mixing of bled steam and feed

water,the steam give up its latent heat and condenses and as a result feed water gets heated.

Indirect contact heater - In this type of heaters , the feed water passes through hairpin tubes in

two,four or occasionally six flows,while the steam is passed over the tubes.Baffles are provided to direct the flow of steam through the tube nest.

Specifications: Pipe Size (DIA X th)

: 16 X 0.889

Type

: shell and tube U – Bend Tubes

Position

: Horizontal

Total tube Surface Area

: 460 Sq. M

No. of water pass

: Two

No. of Tubes

: 498

3.3.6 Condenser:

The work done and efficiency of a steam turbine plant is increased if the exhaust pressure of the turbine is reduced.This is because of the fact that the average temperature at which heat is rejected in a cycle is reduced.It can be made possible by employing a condenser in which steam exhausts and gets condensed. Thus, condenser is defined as a closed vessel in which steam from steam turbine is condensed by cooling water and vacuum is maintained , resulting in an increase in work done and efficiency of a steam power plant and use of condensate as the feed water to the boiler.

Specifications: Manufacturer

: BHEL, Hardwar

Type and Number of Pass

: Surface type / 2 - Pass

Design condition : 250 MW, CW Inlet Temp. 31.2 0C. Cooling water flow Water Velocity

41

Total head drop across condenser ( CW inlet flange to CW outlet flange ) : 31700 M3 / hr. No. of Passes

:2

Arrangement with respect to turbine Axis

: Perpendicular

Boiler feed pump: This pump increases the pressure of the feed water upto boiler pressure to push the feed water into the boiler.Boiler feed pumps are multistage as they increase the pressure of the fluid flow to a very high value. Specifications: Make / Model

: VOITH, Germany, R16K.1

Manufacturer

: BHEL, Hyderabad

Model Number and No. of Pumps

: FK6D30 / 3 Nos.

Casing outer, type

: Barrel type

Casing inner, type

: Radially split type

Casing design pressure (ata) and minimum wall thickness (mm ) : 292 / 62 Booster / Main Pump flow

: 458540 Kg/hr. ( 505 m3 / hr.)

Design inlet conditions

Suction Temperature

: 159.2 Deg. C

Suction pressure ( Booster / Main pump ) : 7.204 ata

42

Condensate extraction pump: This pump extracts condensate from the condenser system and pushes the fluid into the feed water heater circuit.

Specifications: Manufacturer

: BHEL, Hyderabad

Model Number and No. of Pumps : EN6J40 / 500, 2 Nos. Number of stages

: 6 ( Six )

Type of first stage impeller

: Double suction, radial

Impeller diameter

: 388 mm (OD)

Suction specific speed (US Units) : 11080 Design pressure of bowl and discharge Components

: 39 ata

Inlet Temperature

: 44.4 Deg. C

Discharge pressure

: 24.3 ata

43

CHAPTER 4 Exergy analysis of components in the power plants

4.1 Boiler

Fig4.1 Boiler

Mass balance:-

m28 +m1+m3=m2+m4+m31’ Energy balance:-

m28h28+ m1h1+ m3h3= m2h2+m4h4+m31h31 Boiler efficiency:Boiler efficiency=

steam flow rate



 steam enthalpy  feed water enthalpy  100

fuel firing rate  calorific value of fuel

boiler =ms(h2-h1)+mr (h4-h3)/(m f )

44

×LHV

4.1

Exergy analysis:-

Exergy in (Ein)=E1+E3+E28+E30 Exergy out(Eout)=E2+E4+E31 Work input(W)=W fan =1978 kw Exergy destruction(Ed)=W+Ein-Eout Second law efficiency II

=(E2+E4-E1-E3)/(E28+E30+E31+Wfan)

4.2 Steam turbine

Fig 4.2 Turbine Mass balance:-

m2+m4=m3+m5+m6+m7+m8+m9+m10+m11+m12 Energy balance:-

m2h2+m4h4=m3h3+m5h5+m6h6+m7h7+m8h8+m9h9+m10h10+m11h11+m12h12+Wturbine

Exergy balance:-

Exergy in (Ein)=E2+E4 Exergy out(Eout)=E3+E5+E6+E7+E8+E9+E10+E11+E12 Work output(W)=W turbine =250000 kw Exergy destruction(Ed)= Ein-Eout -Wturbine Second law efficiency II

45

=( Wturbine)/( E2+E4-( E3+E5+E6+E7+E8+E9+E10+E11+E12)

4.3 Air fan

Fig 4.3 Air fan Mass balance:-

m35=m29 Energy balance:-

m35h35+Wfan=m29h29 Exergy balance:-

Exergy in (Ein)=E35 Exergy out(Eout)=E29 Work input(W)=W fan =910kw Exergy destruction(Ed)= Ein+Wfan- Eo

Second law efficiency: II

46

=( E35-E29)/( Wfan)

4.4 Air preheater

Fig 4.4 Air preheater

Mass balance:-

m31+m29=m30+m32 Energy balance:-

m31h31+m29h29=m30h30+m32h32

Exergy balance:-

Exergy in (Ein)=E29+E31 Exergy out(Eout)=E30+E32 Exergy destruction(Ed)= Ein- Eout


47

=( E30-E29)/( E33-E32)

4.5Condenser

Fig 4.5 Condenser

Mass balance:-


m12h12+m33h33=m13h13+m34h34 Exergy balance:-



=( Eout)/( Ein)

=( E13+E34)/( E12+E33)

48

4.6Feed water heater1

Fig 4.6 Feed water heater

Mass balance:-


m5h5+m26h26=m1h1+m27h27

Exergy balance:-



49

=( E1-E26)/( E5-E27)

4.7 Deaerator

Fig4.7 Deaerator Mass balance:-

m7+m22+m24=m23

Energy balance:-

m7h7+m22h22+m24h24=m23h23

Exergy balance:-

Exergy in (Ein)=E7+E22+E24 Exergy out(Eout)=E23 Exergy destruction(Ed)= Ein- Eout Second law efficiency: II

=( Eout)/( Ein) =( E23)/( E7+E22+E24)

50

4.8 Condenser pump P1

Fig 4.8 condenser pump P1

Mass balance:-

m13=m14

Energy balance:-

m13h13+W p1=m14h14 Exergy balance:-

Exergy in (Ein)=E13 Exergy out(Eout)=E14 Work input=772kw Exergy destruction(Ed)= Ein- Eout +W p1 Second law efficiency: II

=( Eout)/( Ein)

=( E13-E14)/( W p1)

51

4.9 Circulation pump

Fig4.9 Circulation pump

Mass balance:-

m23=m25 Energy balance:-

m23h23+W p2=m25h25 Exergy balance:-

Exergy in (Ein)=E23 Exergy out(Eout)=E25 Work input=3270kw Exergy destruction(Ed)= Ein- Eout +W p2

Second law efficiency II

=( Eout)/( Ein) =( E23-E25)/( W p2)

52

CHAPTER 5 RESULT AND DISCUSSION

5.1Analysis with a full load operation condition

Energy and exergy analysis has been performed in details in accordance with theoretical expression , parameter and assumptions mentioned in chapter 3 and 4 all of the important components , subsystems and the entire system had been covered in analysis with full load operating condition . The power plant was analysed using the above relation nothing that the environment reference temperature and pressure are298.15K and 1.013 bar respectively.the distribution of exergy addition,exergy losses and exergy consumption for different ,components has been worked out on the basis of analysis exergetic efficiency for boiler,turbine and other calculated. Table 5.1 exergy efficiency and exergy destruction calculation

53

components have been

Based on the analysis ,interesting results and innovative ideas are presented here which directly or indirectly help to improve the performance of exsisting coal power plants into design more energy efficient power plant for the future.

.

Fig 5.1 Graphical representation of exergetic efficiency of different units of the power plant

Inference:- The graph clearly shows that the turbine has maximum exergetic efficiency boiler shows minimum exergetic efficiency and maximum exergy destruction.

54

while the

Fig5.2 Pie chart for exergy destruction in various components of the power plant.

Inference:- the Pie chart shows that a major part of the exergy destruction takes place in the boiler .of the remaining part of the total exergy destruction condenser, feed water heaters play a major role.

55

5.2 Analysis of steam generator(boiler)

Boiler is the location for most of the exergy destruction in the plant and needs maximum attention on its designing and operation forn an optimum use of available energy of the fuel.

. Adiabatic combustion of coal in boiler to convert its chemical energy to thermal energy ,results in consumption of exergy.further this thermal energy is transferred to working fluid( in the form of heat)across a larger temperature difference ,which invites excessive exergy conversion steam urbine at boiler outlet at conventional plant varies from 435 0C to 4600C with feed water inlet turbine of 1400C to 1950C while the furnace temperature is around 850-11500C in radient zone and flue gas varies from 3500Cto 7500Cin conventive zone. In boiler,various heat exchangers (sensible heat exchangers i.e. economizer, vaporizers i.e. super heaters,prmary super heaters,de super heaters and secondary super heaters and air preheater) are arranged in a manner to obtain maximum heat transfer through an optimum combination of radient and convective heat transfer.water is added to steam (at first and second stage of attemperation)on its way of super heating for an effective control of steam temperature at different locations.

Based on energy conversion and energy losses,thermal efficiency of the boiler is found to be 48.70% in case of present working data. Based on exergy losses and destruction ,exergetic efficiency of the boiler has been worked out as 21.708% in case of present working data.

56

Fig 5.3 thermal and exergetic efficiency comparison

In the analysis of the plant the cycle was assumed to be operate at steady state with no heat transfer from any component to its surrounding and negligible kinetic and potential energy effect. Certain compound such as boiler stop valve, fuel oil pump coolers, induced draught and forced draught fan neglected in the analysis and pressure drop along pipe line were assumed to be negligible.

In order to perform the exergy analysis of the plant ,the details steam properties , mass ,ene rgy , exergy balance for the unit were conducted. The exergy value of each component was calculated by the energy component is in an open (control volume ) system and there are only physical exergy associated with material steam for this calculation , specific enthalpy and specific entropy are due to the difference in temperature and pressure between streams .this mean that the exergy input of each component was calculated by the difference between two streams . It is apparent from the boiler analysis ,energy efficiency is 48.70% and exergy efficiency is 21.708% for working data .In boiler subsystem the maximum exergy and energy efficiency is obtained for combustion in the boiler. This large exergy loss is mainly due to the combustion reaction and to the large temperature difference during heat transfer between the combustion gas and steam . .

57

5.2.1 Effect of surrounding temperature on exergetic efficiency of the boiler The exergy analyisis for the boiler was performed for different surrounding temperatures(dead 0

state).Study was made for the temperature of 10,15,20,25 and 30 C.The analysis showed that with an increase in the surrounding temperature causes a decrease in the exergetic efficiency of the boiler. Table 5.2 Boiler efficiency variation with temperature

% EXERGETIC

% EXERGY

TEMPERATURE(K)

EFFICIENCY

DESTRUCTION

283

23.14

60.99

288

22.85

61.671

293

22.565

62.352

298

22.27

63.21

303

21.97

63.74

Inference:-the table clearly shows that as the reference temperature increases there is a reduction in the boiler exergetic efficiency and a increase in the exergy destruction.

Fig5.4 Graphical representation of the variation of boiler exergetic efficiency with a variation in reference temperature

Inference:- it is observed that the exergetic efficiency of the boiler is 23.94% at 283K which reduces to 21.97% at 303K.

58

5.3 Analysis of turbine Based on the exergy associated with incoming and outgoing streams and mechanical output generated by the turbine.thermal efficiency and exergetic efficiency of turbine have been worked as 63.857% and 96.463% for the working data.

Fig5.5 Graphical comparison of the thermal and exergetic efficiency of the turbine

5.3.1 Turbine efficiency variation with temperature The exergy analyisis for the Turbine was performed for different surrounding 0

temperatures(dead state).Study was made for the temperature of 10,15,20,25 and 30 C.The analysis showed that with an increase in the surrounding temperature causes a decrease in the exergetic efficiency of the turbine. Table 5.3:-exergy destruction and exergetic efficiency at different reference temperatures in the turbine

59

Fig 5.6 Graphical representation of the variation of exergetic efficiency with variation in reference temperature . Inference:- it is observed from the graphical representation that the turbine efficiency is as high as 94.21% at 283K which gradually reduces with a rise in reference temperature and finally reaches 92.837% at 303K.

5.4 Study of performance of boiler and air preheater with the usage of different grades of coal in the power plant It is observed that as the grade of coal used in the power plant is changed ,a change in exergetic efficiency and exergy destruction of two components :-Boiler and Air Preheater takes place. This change in performance is mainly due to inability of the components to harness the exergy thus leading to higher exergy destruction and low exergetic efficiency.

60

Table5.4 :-exergy destruction and exergetic efficiency of the boiler for different grades of coal.

Inference:-it is observed that the best exergetic efficiency of the boiler is seen when bituminous coal (designed coal) is used. This is maily because of low exerg destruction ,while for higher grades of coal there is poorer combustion leading to poor exergetic efficiency .

Fig5.7 Graphical representation of boiler efficiency vs calorific value of coal

Inference:- it is observed that highest exergetic efficiency of 39.18% is obtained for calorific value of 3500kj/kg while efficiency of 21.7%is observed when high grade coal with calorific value of 6454kj/kg is used .

61

AIR PREHEATER

Air preheater is also an important component of the power plant in which the flue gases after combustion in the boiler are used to prerheat the primary and secondary air used in combustion processes. Hence ,a clear change in exergetic efficiency of this component is observed with use of different coal grades. Table5.5 :-exergy destruction and exergetic efficiency of air preheater for different coal grades

Fig 5.6 Graphical representation of air preheater exergetic efficiency vs calorific value of coal

Inference:- The effect of exergetic efficiency with different grades of coal has been shown. It is observed that as the calorific value of coal increases the exergetic efficiency decreases.this is because the exergy utilization in the component decreases for the higher grade of coal. It is obsereved that the exergetic efficiency of the air preheater is the highest at 62% when a low grade of coal (3500kj/kg) is used ,while an efficiency of 54.906% is observed when high grade coal (6454 kj/kg ) is used.

62


63

Table 5.7Exergy analysis for temperature (To)=283k.

64

Table 5.8Exergy analysis for temperature (To)=288k.

65


66

Table 5.10Exergy analysis for temperature (To)303k.

67

Composition of grades of coal used for analysis in the project Table 5.11 (a,b,c,d) design coal

bituminous1 component

component

percentage

carbon

32.92

hydrogen

3.2

nitrogen

1.28

sulphur

0.4

oxygen

7.2

moisture

13

percentage

carbon

42

hydrogen

2.76

nitrogen

1.22

sulphur

0.41

oxygen

9.89

moisture

5.98

(a)

(b)

indonesian coal bituminous2

component

component

percentage

carbon

36.22

hydrogen

2.64

nitrogen

1.09

sulphur

0.55

oxygen

7.25

moisture

4.39

(c)

68

Percentage

carbon

58.96

hydrogen

4.16

nitrogen

1.02

sulphur

0.56

oxygen

11.88

moisture

9.43

(d)

CHAPTER 6 C++ PROGRAMME CODING FOR SOME ITERATIVE CALCULATION

6.1 C++ programme coding for combustion calculation #include void main() { clrscr(); float H,C,O,S,N,CO2,SO2,O2,H2O,N2,O2r,O2H,O2S,O2F,n,nCO2,nO2,nSO2,nH2O,nN2,M,pCO2,pO2,pSO2 ,pH2O,pN2; printf("\nenter the percentage of hydrogen ="); scanf("%f",&H); printf("\nenter the percentage of sulphur ="); scanf("%f",&S); printf("\nenter the percentage of oxygen ="); scanf("%f",&O); printf("\nenter the percentage of carbon ="); scanf("%f",&C); printf("\nenter the percentage of nitrogen ="); scanf("%f",&N); printf("\nenter the percentage of moisture =");

69

scanf("%f",&M); CO2=(C*44/1200); printf("\n\nCO2 produced=%f(kg/kg of coal)\n\n",CO2); H2O=(H*9/100)+M/100; printf("\n\nH2O produced=%f(kg/kg of coal)\n\n",H2O); SO2=S*2/100 ; printf("\n\nSO2 produced=%f(kg/kg of coal)\n\n",SO2); N2=(N*2/100)+((254.654/45.86)*.77); printf("\n\nN2 produced=%f(kg/kg of coal)\n\n",N2); O2r=(C*32)/1200; O2H=H*8/100; O2S=S/100; O2F=(O/50)+((254.654/45.86)*.23); O2=O2F-O2r-O2H-O2S; printf("\n\nO2 produced=%f(kg/kg of coal)\n\n",O2); nCO2=CO2/44; nSO2=SO2/64; nH2O=H2O/18; nO2=O2/32; nN2=N2/28; n=nCO2+nSO2+nH2O+nO2+nN2;

70

pCO2=nCO2*100/n; printf("\n\npercentage of CO2 produced=%f\n\n",pCO2); pSO2=nSO2*100/n; printf("\n\npercentage of SO2 produced=%f\n\n",pSO2); pH2O=nH2O*100/n; printf("\n\npercentage of H2O produced=%f\n\n",pH2O); pO2=nO2*100/n; printf("\n\npercentage of O2 produced=%f\n\n",pO2);

pN2=nN2*100/n; printf("\n\npercentage of N2 produced=%f\n\n",pN2); getch(); }

6.2 C++ programme for calculation of chemical exergy of fuel #include #include void main() { clrscr(); float h,c,o,n,b,LHV,ech;

71

printf("\nenter the percentage of hydrogen ="); scanf("%f",&h); printf("\nenter the percentage of carbon ="); scanf("%f",&c); printf("\nenter the percentage of oxygen ="); scanf("%f",&o); printf("\nenter the percentage of nitrogen ="); scanf("%f",&n); b=1.0437+.1882*(h/c)+.0610*(o/c)+.0404*(n/c); printf("\nenter the LHV of coal ="); scanf("%f",&LHV); ech=b*LHV; printf("\n chemical exergy of coal=%f",ech); getch();

}

72

6.3 C++ programme for calculation of density and specific heat of combustion gas #include #include void main() { clrscr(); float Vco2,Vo2,Vco,Vh,Vn,pco2,po2,pco,ph,pn,pgas,Cc; char ans; do { printf("\nenter the volume of co2 ="); scanf("%f",&Vco2); printf("\nenter the volume of o2 ="); scanf("%f",&Vo2); printf("\nenter the volume of co ="); scanf("%f",&Vco); printf("\nenter the volume hydrogen ="); scanf("%f",&Vh); printf("\nenter the volume nitrogen ="); scanf("%f",&Vn);

73

pco2=44/22.4; po2=32/22.4; pco=28/22.4; ph=2/22.4; pn=28/22.4; pgas=(Vco2*pco2+Vo2*po2+Vco*pco+Vh*ph+Vn*pn)/100; printf("\n\ndensity of fuel gas=%f\n\n",pgas); printf("specific heat of CO2=.48 kcal/m3\n\nspecific heat of O2=.334 kcal/m3\n\nspecific heat of N2= .319 kcal/m3\n\nspecific heat of CO= .321 kcal/m3\n\nspecific heat of H2= .312 kcal/m3"); Cc=(Vco2*.48+Vo2*.334+Vn*.319+Vco*.321+Vh*.312)/100; printf("\n\nspecific heat of combustion gas=%f\n\n",Cc); printf("\ndo you want to continue y/n: "); ans=getche(); } while(ans=='y'); }

74

REFERENCES

[1] P.K . Nag , (2008). “Power Plant Engineering”, by Tata McGraw-Hill Publishing Limited, 7 West Patel Nagar, New Delhi 110 008

Company

[2] P.K . Nag , (2008). “Thermo dynamics”, by Tata McGraw-Hill Publishing Company Limited, 7 West Patel Nagar, New Delhi 110 008 [3] Research Paper on “ Energy and Exergy Analysis of a Steam Power Plant in Egypt ” by A. Rashad*, and A. El Maihy* , presented in 13th International Conference on AEROSPACE SCIENCES & AVIATION TECHNOLOGY. [4] Energy and Exergy Analysis of a 500 KW Steam Power Plant at Benso Oil Palm Plantation (BOPP) by C. Mborah and E.K. Gbadam , Mechanical Engineering Department , University of Mines and Technology, Tarkwa, Ghana [5] Book on “THERMODYNAMICS An engineering approach” 2008 by Yunus A. Cengel & Michael A Boles 6th Edn., McGraw Hill Companies, Inc., New York. [6] O.P.Gupta “ Elements of fuels,furnaces and refractory”s by khanna publication [7] R.S.Khurmi “ Tables with Mollier diagram in si units ” by S.Chand and company limited [8] Steam table online.com (http://www.steamtablesonline.com/steam97web.aspx). [9] Flue Gas Properties Calculator(http://www.jehar.com/gasprops.htm) [10] power scenario in india (www.Wikipedia.com) [11] Dr.R.Yadav “Steam and gas turbines and power plant engineering in S.I units.”, central publishing house a , Allahabad. [12] NSPCL technical diary:NSPCL ,Bhilai. [13] G.R. “ Nagpal power lant engineering” khanna publishers

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Exergy Analysis Of Steam Power Plant For Different Grades Of Coal

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