performance evaluation and resource allocation of various systems of a thermal power plant

271 Pages·2010·1.26 MB·English

PERFORMANCE EVALUATION AND RESOURCE
ALLOCATION OF VARIOUS SYSTEMS OF A THERMAL
POWER PLANT

A THESIS

Submitted in fulfillment of the
requirements for the award of the degree
of

DOCTOR OF PHILOSOPHY
in
MECHANICAL ENGINEERING
By

SORABH GUPTA
Regn. No. 2K06-NITK-1108M

DEPARTMENT OF MECHANICAL ENGINEERING
NATIONAL INSTITUTE OF TECHNOLOGY
(INSTITUTION OF NATIONAL IMPORTANCE)
KURUKSHETRA - 136 119 (INDIA)
APRIL, 2010
CERTIFICATE

This is to certify that the thesis entitled “Performance Evaluation and
Resource Allocation of Various Systems of a Thermal Power Plant”,
being submitted by Sorabh Gupta (Regn. No. 2K06-NITK-1108M) to the
Department of Mechanical Engineering, National Institute of Technology,
Kurukshetra for the award of Degree of ‘Doctor of Philosophy’ in
Mechanical Engineering, is a bonafide research work carried out by him
under my supervision and guidance. His thesis has reached the standard of
fulfilling the requirements of regulations relating to degree. The thesis is an
original piece of research work and embodies the findings made by the
research scholar himself.
The results presented have not been submitted in part or in full to any other
University/ Institute for the award of any degree or diploma.

(Dr. P. C. Tewari) Date:
Supervisor
Associate Professor
Department of Mechanical Engineering
N.I.T. Kurukshetra

The Ph.D. Viva-Voce examination of Mr. Sorabh Gupta, Research Scholar,
has been held on ________________.

Supervisor External Examiner
i
CANDIDATE’S DECLARATION

I hereby certify that the work which is being presented in the thesis, entitled
“Performance Evaluation and Resource Allocation of Various Systems
of a Thermal Power Plant”, in the fulfillment of the requirements for the
award of the degree of Doctor of Philosophy and submitted in the
Department of Mechanical Engineering of National Institute of Technology,
Kurukshetra, is an authentic record of my own work carried out under
supervision of Dr. P. C. Tewari, Associate Professor, Department of
Mechanical Engineering, National Institute of Technology, Kurukshetra
(Haryana), India.
The matter presented in this thesis has not been submitted by me for the
award of any degree of this or any other University/Institute.

(Sorabh Gupta) Date:
ii
PREFACE AND ACKNOWLEDGMENTS

The research work presented in this Ph.D. thesis has been carried out at National
Institute of Technology, under the supervision of Dr. P.C. Tewari, Associate
Professor, Department of Mechanical Engineering, during the period July 2006 to
March 2010.
I wish to express sincere thanks to my supervisor Dr. P.C. Tewari for introducing
me to the subject area of reliability, availability, maintainability and resource
allocation, for his thoughtful supervision, constant inspiration, steady support,
guidance and for making available critical facilities throughout the course of this
work.
I would like to thank complete faculty and specially Dr. S. S. Rattan and Dr. K.S.
Kasana of Department of Mechanical Engineering, National Institute of
Technology, Kurukshetra for their support and guidance during my research.
I am grateful to the management of Haryana Institute of Engineering and
Technology, Kaithal (Haryana), INDIA to provide me permission and support to
undertake this research work.
I would also like to thank my colleagues in HCTM and HIET. They encouraged me
through discussions and valuable advice.
I am also thankful to authorities of Panipat Thermal Power Plant for providing me
the opportunities to carryout my research.
I would like to express my thanks to my wife Shipra and son Shaurya, for their
endless support and patience.
I take this opportunity to express my deep and heartfelt gratitude to my mother
Smt. Rani Devi and my father Sh. P.D. Gupta. They have unselfishly given so much
to create the opportunity for me both to grow as a person and to be able to secure
an outstanding education.
Finally, I wish to express my gratitude to all my family members, especially my
brother and my sister for their support, kindness and encouragement.

Sorabh Gupta
April, 2010
NIT Kurukshetra, India
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ABSTRACT

Today, all the industries face high customer expectations for quality and reliability of
products but in contraposition with severe cost constraints and with the pressure for
shorter product cycle time. The fundamental operating feature of the power system is that
the electrical energy production and consumption are simultaneous. Therefore, the
reliability requirement within the thermal industry is very high. The maintenance of
power system equipment and especially the maintenance of generating units are implicitly
related to thermal power system reliability and have a tremendous bearing on the
operation of the thermal power system. Hence, the maintenance problem has always been
investigated together with system reliability engineering research.
The importance of obtaining a highly reliable system has recently been recognized with
increasing automation and use of highly complex systems. Reliability characteristics such
as: availability, probability of survival, mean time to system failure, mean down time and
frequency of failures are some of the measures of system effectiveness, which provide the
necessary criteria for alternative design policies to be compared, judged and selected to
give the best results. Manufacturing process involves a continuous flow of raw material
through a series of sequential operations. These operations transform the raw material
into final product. Examples of process industries are thermal, chemical, fertilizer, sugar,
paper, oil refinery and textile etc. Such industries have continuous operation and
hazardous work environment. Accomplishment of goal of high productivity with least
number of standby units, minimum storage capacity, reduction in losses and least cost of
failures, in these industries is not an easy task. In multipurpose process plants, which are
characterized by sharing different resources (equipment, manpower etc.) for production,
unplanned equipment shutdown could affect the timely production of products and hence
process profitability. Thus, the importance of reliable operation has also been realized in
such plants of complex configurations.
The ability to improve continually is desirable. In recent years, reliability, availability,
maintainability, performance evaluation as well as resource allocation have become big
issues in the power industries. Major causes of customer dissatisfaction often result from
unexpected failures, which lead to unanticipated cost in the thermal power plant.
However, with proper integration of reliability, availability, maintainability, performance
evaluation as well as resource allocation in the thermal power plant, the frequency of
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failures can be reduced and their consequences can be diminished. The scientific
approach of performance evaluation is to develop availability models, which are in
mathematical form and used to evaluate the performance of various systems of thermal
power plant and hence to take the appropriate maintenance decisions.
Complex repairable systems present scenarios wherein operating and maintenance
activities take place and multiple entities (persons, machines and environment) interact in
a complex manner. Dynamic changes usually occur in the entities themselves. The
behaviour of such systems can be studied in terms of their reliability, availability and
maintainability, if the real system is modeled mathematically and analyzed in real
working environment. In many practical system design situations, the overall system is
partitioned into a specific number of subsystems, according to the function requirements
of the system. For each subsystem, there are different component types available with
varying reliability, cost, weight, volume and other characteristics. The system reliability
depends on the reliability of each subsystem. In real situations, in a process plant the raw
material is processed through various equipment to achieve the final product. Various
subsystems of a system are subjected to random failures and these critical failures
associated with production systems, can result in huge environmental, health and
financial losses. To achieve the goal of maximum power generation, it is required to run
the various units of the thermal power plant failure free for a long duration. The failed
systems can be brought back to working states in minimum down time through effective
maintenance planning and decisions. The plant operating conditions and the repair
strategies play an important role in maintaining the systems operative for maximum
duration i.e. optimal system availability. This can be accomplished only through
performance evaluation and analysis of each operating system of the plant.
For thermal power plant, which comprises of complex systems, research efforts have
largely focused on performance evaluation of various systems of thermal power plant
followed by efficient resource allocation. Thus, this report deals with the opportunities
for the availability modeling and resource allocation in a thermal power plant. These
opportunities are identified by evaluation of availability models developed for the various
systems of Panipat Thermal Power Plant. For this purpose simple probabilistic approach
and Markov birth death process have been used. The differential equations associated
with the various operating systems of thermal power plant have been developed. These
equations have been solved recursively and reduced to steady state condition (condition
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for long run availability of the process plant). The steady state availability expressions
have been derived, indicating the interrelation of states of nature (f ) and courses of
action (l ) for various operating systems of the thermal power plant. The study has been
conducted in thermal power plant at Panipat (North India).
Thermal power plant is a complex engineering process consisting of various systems like
Coal Handling, Coal Crushing, Feed Water, Steam and Water, Condensate, Flue Gas and
Air, Power Generation and Ash Handling System. The states of nature (f ) and courses of
action (l ) for various operating systems of the thermal power plant have been recorded
for making the performance evaluation. The relative performance of each operating
system of the thermal power plant has been analyzed and critical subsystems have been
located. The availability of each operating system (in operation) has been tabulated in the
form of availability matrices and analyzed in different situations of working environment.
The performance level has been predicted and utilized in determining the various feasible
ranges of states of nature and courses of action values for various operating systems of
the thermal power plant. The availability level for each system of the thermal power plant
has been calculated and used for allocating the resources. For the purpose of resource
allocation, the plant has been modeled as n stage system and the recursive equation has
been developed. The objective function is to maximize the profit subject to resource
constraints. Dynamic programming method has been used to solve the multi stage
decision problem. Lagrange’s multiplier has been used to reduce the dimension of the
problem (from multi constraint function into single constraint function). Allocation of
resources for each operating system of the thermal power plant has been worked out. The
break even points have also been indicated. Break even analysis helps the plant
management in deciding the availability level and allocation of resources for a desired

level of profit.
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LIST OF CONTENTS

Title Page No.

Certificate.......................................................................................................................i
Candidate’s Declaration.................................................................................................ii
Preface and Acknowledgements....................................................................................iii
Abstract .........................................................................................................................iv
List of Contents .............................................................................................................vii
List of Figures................................................................................................................x
List of Tables ...............................................................................................................xiii
Notations and Abbreviations..........................................................................................xv
List of Research Papers .................................................................................................xvii
Some Basic Definitions ................................................................................................xx

CHAPTER 1: INTRODUCTION 1-30

1.1 Theory ………………………………………………………………………….....1
1.2 Maintenance in Process Industry ………………………………………………....3
1.2.1 Stages of Maturity for Maintenance Policies …………………………….4
1.2.2 Maintenance Economics…………………………………………………..5
1.3 Availability in Process Industry……………………………………………….......6
1.3.1 Types of Availability ……………………………………………………10
1.3.2 Factors Influencing the Availability……………………………………...11
1.3.3 How can Reliability, Maintainability and thus Availability be Improved.13
1.4 Status of Thermal Energy in India………………………………………..……...16
1.5 Modeling ………………………………………………………………………...18
1.5.1 General Modeling and Simulation Modeling …………………………...18
1.5.2 Reliability Block Diagram (RBD)…………………………………….....18
1.5.3 Markov Modeling………………………………………………………..20
1.5.4 Availability Modeling……………………………………………………21
1.6 Performance Evaluation and Analysis…………………………………………...23
1.7 Resource Allocation……………………………………………………………...25
1.8 Research Problem and Approach………………………………………………...26
1.9 Architecture of the Thesis………………………………………………………..28
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CHAPTER 2: LITERATURE REVIEW 31-50

2.1 Brief History and Need of Reliability ………………………………………….. 31
2.2 Maintenance of Repairable Systems…………………………………………….34
2.3 Markovian Theory...…..………..………………………………………………..35
2.4 Monte Carlo Simulation Modeling…..……………………………………...….. 37
2.5 Common Cause Failures in Systems…………………………………….. ……..39
2.6 Availability Analysis Using Redundancy Allocation …………………….……..40
2.7 Reliability, Availability and Maintainability…………………………………….41
2.8 Performance Evaluation and Analysis in Process Industries……………… … 44
2.9 Resource Allocation in Process Industries……………………………………… 46
2.10 Present Scenario………………………………………………………………….47
2.11 Summary…………………………………………………………………………49

CHAPTER 3: DEVELOPMENT AND FORMULATION OF AVAILABILITY
MODELS 51-105

3.1 Importance of Reliable System…………………………………..…………….. 51
3.2 General Layout and Description of the Plant………………………………..…..65
3.3 Assumptions ……………………………………..……………………… ……. 67
3.4 Summary of Notations Used For Modeling and Performance Evaluation….…..67
3.5 Thermal Power Plant Description…………………………… …………………69
3.5.1 Coal Handling System……………………………………………..…….69
3.5.2 Coal Crushing System …………………………………………………..70
3.5.3 Feed Water System……………………………………………………... 70
3.5.4 Steam and Water System ………………………………………………..71
3.5.5 Condensate System……………………………………………….……...71
3.5.6 Power Generation System………………………………………….. …...72
3.5.7 Flue Gas and Air System ………………………………………………..72
3.5.8 Ash Handling System…………………………………………………....73
3.6 Probabilistic Mathematical Modeling ……………………………………..…… 73
3.6.1 Generation of Differential Equations………………………………….... 74
3.6.2 Steady State Availability Using Normalizing Condition……………..... .93

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4. PERFORMANCE EVALUATION AND ANALYSIS 106-189

4.1 Importance of Performance Evaluation……………………………………… 106
4.2 Availability Matrices ………………………………………………………….107
4.2.1 Development of availability matrix…………………………………….107
4.3 Performance Evaluation of Systems………………………………………….. .109
4.3.1 Performance evaluation of Coal Handling System………………. ….131
4.3.2 Performance evaluation of Coal Crushing System………………… ….132
4.3.3 Performance evaluation of Feed Water System …………………… ….134
4.3.4 Performance evaluation of Steam and Water System ………………….136
4.3.5 Performance evaluation of Condensate System……………………… .138
4.3.6 Performance evaluation of Power Generation System…………… …..140
4.3.7 Performance evaluation of Flue Gas and Air System ………………….142
4.3.8 Performance evaluation of Ash Handling System……………………..143
4.4 Feasible Combinations of States of Nature and Courses of Action………........183
4.5 Performance Analysis of Systems…………………………………………. ….186

5 RESOURCE ALLOCATION AND PROFIT ANALYSIS 189-225

5.1 Importance and Need of Resource Allocation …………………………………189
5.1.1 Dynamic Programming Technique ………………………………….....190
5.2. Development of Resource Allocation Model……………………………….….191
5.3 Allocation of Resources to Systems ………………………………………….194
5.4 Profit Analysis………………………………………………………………… 221

6. CONCLUSIONS 226-228

SCOPE FOR FUTURE RESEARCH WORK 229

APPENDICES 230-231
Appendix 1 Feasible combinations of states of nature and courses of action ………230
Appendix 2 Optimal values of stage allocation (e ) and state function f(e )……. …231
0 0

REFERENCES 232-250
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