United States Industrial Environmental Research EPA-600/7-79-113
Environmental Protection Laboratory May 1979
Agency Research Triangle Park NC 27711
Comparison of the
Availability and Reliability
of Equipment in the
Electric Utility Industry
Interagency
Energy/Environment
R&D Program Report
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
6. Scientific and Technical Assessment Reports (STAR)
7. Interagency Energy-Environment Research and Development
8. "Special" Reports
9. Miscellaneous Reports
This report has been assigned to the INTERAGENCY ENERGY-ENVIRONMENT
RESEARCH AND DEVELOPMENT series. Reports in this series result from the
effort funded under the 17-agency Federal Energy/Environment Research and
Development Program. These studies relate to EPA's mission to protect the public
health and welfare from adverse effects of pollutants associated with energy sys-
tems. The goal of the Program is to assure the rapid development of domestic
energy supplies in an environmentally-compatible manner by providing the nec-
essary environmental data and control technology. Investigations include analy-
ses of the transport of energy-related pollutants and their health and ecological
effects; assessments of, and development of, control technologies for energy
systems; and integrated assessments of a wide-range of energy-related environ-
mental issues.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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EPA-600/7-79-113
May 1979
Comparison of the Availability
and Reliability of Equipment in
the Electric Utility Industry
by
J. C. Dickerman, R. T. Coleman, J. M. Burke, and C. C. Thomas
Radian Corporation
P. 0. Box 9948
Austin, Texas 78766
Contract No. 68-02-26O8
Task No. 48
Program Element No. EHE624
EPA Project Officer: John E. Williams
Industrial Environmental Research Laboratory
Office of Energy, Minerals, and Industry
Research Triangle Park, NC 27711
Prepared for
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Research and Development
Washington, DC 20460
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ABSTRACT
This report presents the findings of a study to compare the reliability/
availability of flue gas desulfurization systems with equipment commonly used
in the electric utility industry. Because many of the parameters used to
report performance data for these systems have different definitions from one
data reporting system to another, a direct comparison cannot be made. For
this reason, a comparison model was developed to incorporate such factors as
reliability, development status, and repair effort to result in a single
statistic which can be used to directly compare dissimilar pieces of equipment
or systems.
Results of this study indicate that a statistically meaningful comparison
of the reliability/availability of utility and FGD systems cannot now be made,
primarily because of the small amount of FGD system performance data currently
available. A meaningful comparison can be made only after more FGD systems
are installed and more complete performance records become available.
ii
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CONTENTS
Abstract ii
Figures V
Tables Vi
Conversion Table Vii
1. EXECUTIVE SUMMARY 1
2. INTRODUCTION 4
2.1 Program Obj active 5
2.2 Approach 6
3. DESCRIPTIONS OF UTILITY EQUIPMENT AND FGD SYSTEMS 7
3.1 Electric Utility Equipment Descriptions 7
3.1.1 Utility Boilers 8
3.1.2 Turbines 12
3.1.3 Generators 13
3.1.4 Condensers 14
3.1.5 Gas Turbines 14
3.2 FGD Systems 14
3.2.1 General Lime/Limestone FGD Systems 16
3.2.2 Specific Lime/Limestone Systems 20
4. COMPARISON BASIS
4.1 Development of the Comparison Basis 21
4.2 Model Description 25
4.3 Model Discussion 27
4.3.1 Discussion of Term I 27
4.3.2 Discussion of Term II 29
4.3.3 Discussion of Term III 29
5. UTILITY COMPONENT OPERATING DATA 30
5.1 Def inlt ion of Terms 30
iii
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CONTENTS (Continued)
5.2 Sources and Availability of Data 31
5.3 Utility Data Presentation 32
5.3.1 EE1 Data Summary 33
5.3.2 Replicate Unit Data 46
5.4 Data Trends 46
6. FGD SYSTEM OPERATING DATA 53
6.1 Definition of Terms 53
6.2 Sources and Availability of Data 54
6.3 Data Presentation 59
6.4 Data Trends 64
7. RESULTS 70
8. CONCLUSIONS AND RECOMMENDATIONS 74
8.1 Conclusions 74
8. 2 Recommendat ions 75
BIBLIOGRAPHY 77
APPENDIX A - MODEL DEVELOPMENT 79
APPENDIX B - UTILITY COMPONENT DATA 87
APPENDIX C - FGD SYSTEM DATA 103
APPENDIX D - FGD SYSTEMS 194
iv
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FIGURES
Number Page
3-1 Simplified flowscheme for an electric power generating
station. 9
3-2 Simple-cycle gas turbine flowscheme 15
3-3 General lime/limes tone FGD system 17
5-1 Availability of gas turbines vs. years in service 45
5-2 Forced-outage rates for three 1,300 MW units plus 800 MW
Big Sandy 2 47
5-3 Typical failure-rate characteristic for engineering devices.. 48
5-4 Equipment Maturity 49
5-5 Boiler and unit maturity 390-599 MW 51
5-6 Boiler and unit maturity 600 MW 52
6-1 Data Form 1 56
6-2 Data Form 2 56
6-3 Data Form 3 57
6-4 Will County FGD system availability - Module A 65
6-5 Green River FGD system availability 66
6-6 LaCygne FGD system availability - average all modules 67
6-7 Cholla FGD system reliability - Module A 69
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TABLES
Number Page
5-1 Operating Statistics of Controlled Circulation Boilers 34
5-2 Operating Statistics of Once-Through Super Critical Boilers... 36
5-3 Operating Statistics of Once-Through Subcritical Boilers 37
5-4 Operating Statistics of Single Shaft Generators 38
5-5 Operating Statistics of Tandem Compound Subcritical Turbines.. 40
5-6 Operating Statistics of Tandem Compound Super Critical Turbines 41
5-7 Operating Statistics of Cross Compound Subcritical Turbines— 42
5-8 Operating Statistics of Cross Compound Super Critical Turbines 43
5-9 Operating Statistics for Gas Turbines 44
6-1 Data Available From PEDCo' s FGD Summary Report 54
6-2 Data Collected by Radian 58
6-3 Performance Data Collection vs. System Operation 59
6-4 FGD System Performance Data - Average Values 60
6-5 Ranges for Performance Parameters 61
7-1 Projected Confidence Limits for Availability Parmeter -
Lime /Limes tone Systems 72
vi
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CONVERSION TABLE
It is EPA policy to report measurements in the international system of
metric units. For clarity of presentation, units used in this report are
those commonly used in engineering calculations in the U.S. Factors to con-
vert the units used in this report to metric units are provided below.
To convert from
Btu
Btu/lb
Cubic feet
Standard cubic feet
Acres
Gallons
Inches of
Founds
Tons
°F
To
Joules
Joules/gram
Cubic meters
Normal cubic meters
Square meters
Liters
Kilograms/square meters
Kilograms
Kilograms
°C
Multiply by
1055.1
2.32
0.028
0.0268
4046.8
3.785
25.4
0.454
907.18
(°F-32) x 0.555
vii
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SECTION 1
EXECUTIVE SUMMARY
A controversy concerning the reliability/availability of flue gas
desulfurization (FGD) systems has continued for several years between members
of the electric utility industry and the Environmental Protection Agency
(EPA). The electric utility industry maintains that FGD technology is unreli-
able while the EPA maintains it is reliable. Radian Corporation has been
contracted by both the Environmental Protection Agency and the Council on
Environmental Quality to compare the commercial and technical status and
feasibility of the FGD systems with respect to conventional equipment pre-
sently accepted and used by the electric utility industry.
Many parameters are currently being used to report the performance of
electric utility components and FGD systems. These parameters may have the
same name but different definitions from one data reporting system to another.
Additionally, there is no one parameter within the existing data bank that
can be used directly for comparison and ranking of dissimilar pieces of
equipment or systems. In an attempt to directly compare the relative merits
of FGD systems and utility equipment components, a Figure of Merit was
developed. The Figure of Merit is a parameter which incorporates such factors
as reliability, development status, and repair effort; and results in a single
statistic which can be used to compare dissimilar pieces of equipment or
systems.
There are four major utility equipment items which are of interest to
this study: boilers, turbines, generators, and gas turbines. These items
are currently used by virtually every utility in the United States. Gas
turbines are the least common of these equipment items, although there are
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more than five hundred gas turbines currently in operation. There are two
basic reasons for selecting these utility components for study. First, each
is generally accepted by the electric power utility industry as being com-
mercially demonstrated technology. Second, data has been recorded and in
many cases is available concerning the reliability, availability, and failure
rates of each of these equipment items.
The evaluation of performance data for FGD systems was limited exclusive-
ly to lime and limestone systems for the following reasons: 1) lime/limestone
FGD systems have been installed and operated on a commercial scale in the
United States; 2) three full scale (65 MW or larger) lime/limestone FGD
systems have a relatively long (greater than 3 years) operating history;
3) lime/limestone FGD systems are considered commercial technology by the EPA;
and 4) performance data for six lime/limestone FGD systems are readily avail-
able. An evaluation of the literature indentified 17 operating lime/limestone
slurry scrubbing processes. However, 5 of the 17 lime /limestone systems are
treating flue gas from units under 50 MW in size. In addition, long-term
(greater than 1 year) performance data does not exist for 6 of the 12 systems
treating flue gas from units larger than 50 MW. As a result of this screen-
ing process, the following 6 FGD systems were identified as best suited for
detailed study.
1) Arizona Public Service Company's Cholla Generating
Station - Unit No. 1
2) Commonwealth Edison Company's Will County Station -
Unit No. 1
3) Duquesne Light Company's Phillips Station
4) Kansas City Power and Light Company's LaCygne Station
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5) Kentucky Utilities Company's Green River Station
6) Louisville Gas and Electric Company's Paddy's Run
Station - Unit No. 6
Three major conclusions can be drawn from the results of this study.
First, a statistically meaningful comparison of the reliability/availability
of utility and FGD systems cannot now be made, primarily because of the small
amount of FGD system performance data currently available. A meaningful com-
parison can be made only after more FGD systems are installed and more com-
plete performance records become available. Second, the comparison model
or Figure of Merit provides a better basis of comparing or ranking dissimilar
pieces of equipment or systems than any single parameter currently being
recorded. At this time, only Term I and Term II of the Figure of Merit can
be used. The learning curve portion, Term III of the Figure of Merit, does
not have sufficient available data. Finally the products of Term I and
Term II of the Figure of Merit are greater than 50 for an equipment installed
by the Electric Utility Industry. FGD Systems must, therefore, establish an
operating history, such that the same product within the Figure of Merit is
greater than 50 in order to demonstrate performances comparable to utility
components.
This report combines the FGD operating history reported by Radian in
EPA Contract #68-02-1319, Task 62 with an entirely new utility data search.
Thus Section 5.0 and parts of Sections 7.0 and 8.0 pertaining to the utility
data have been completely rewritten. The report has been completely reissued
to preserve the context of the material and to retain all of the material with-
in one report.
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SECTION 2
INTRODUCTION
The controversy surrounding the implementation of flue gas desulfurization
technology in the electric utility industry has continued for at least the
past five years. While the spokesmen on both sides to some degree have
changed, and while the arguments have undergone periodic variations, a con-
sistent theme on the part of the electric utility industry is that scrubbers
represent unreliable technology and that technology should not be forced upon
the electric utility industry unless it is at least as reliable as technology
presently utilized in that industry. This has been the crux of the issue.
The Environmental Protection Agency (EPA) maintains the technology is reli-
able; the electric utility industry steadfastly maintains it is unreliable.
The positions of both EPA and the electric utility industry are contained
in a document entitled: Report of the Hearing Panel - National Public Hear-
ings on Power Plant Compliance with Sulfur Oxide Air Pollution Regulations
(EN-211). This document summarizes the public hearings which took place
during the period October 18, 1973 through November 2, 1973.
The EPA panel which conducted the hearings prepared findings and recom-
mendations based on the testimony presented. Of principal interest is the
following:
"Although most utility witnesses testified that FGD technology
was unreliable, that it created difficult sludge disposal pro-
blems, and that it cost too much, the hearing panel finds, on
the basis of utility and FGD vendor testimony, that the alleged
problems can be, and have been, solved at a reasonable cost.
The reliability of both throwaway-product and saleable-product
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FGD systems has been sufficiently demonstrated on full scale
units to warrant widespread commitments to FGD systems for SO
control at coal- and oil-fired power plants."
This finding from the 1973 hearings has fueled the fires for debate on
the issue of reliability of flue gas desulfurization (FGD) systems. Both the
Environmental Protection Agency and the Electric Power Research Institute
have programs underway to address the issue of FGD system reliability. In
general, these studies are reporting improved scrubber reliability and better
performance over that experienced in the recent past. The question remains
as to whether FGD technology is too unreliable compared to other components
in the electric utility industry.
Under contract to both the Environmental Protection Agency and the
Council on Environmental Quality, Radian Corporation has conducted a study
to compare the reliability of FGD systems with other components in the elec-
tric utility power generating system. Data and results drawn from this study
are presented in the following sections of this report. Section 3.0 is a
general description of the FGD and utility systems compared. Section 4.0
outlines the comparison basis and Sections 5.0 and 6.0 present the utility
and FGD data. Study results are given in Section 7.0 and conclusions and
recommendations in Section 8.0.
2.1 PROGRAM OBJECTIVE
The overall objective of this study was to compare the reliability/
availability of FGD systems with conventional fossil fueled equipment pre-
sently accepted and used by the electric utility industry. To accomplish
this objective a comparison basis was formulated, and available performance
data were gathered on both utility and FGD systems.
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2.2 APPROACH
The initial task in this study was to formulate a basis for comparing
FGD and utility equipment operating data. Since there is no standard proce-
dure for reporting reliability data, a comparison of utility component and
FGD system reliability is nontrivial. The requirement for a standard com-
parison basis was of prime importance to the conduct of this study. The
comparison basis was formulated in an attempt to normalize the differences
in data reporting, system design, and operating practices.
Data collection and analysis were identified concurrently with the formu-
lation of the comparison basis. A literature search was conducted to retrieve
reliability data on utility system components and FGD systems available in
the open literature. In addition, contacts were made with the Federal Energy
Administration (FEA), the Edison Electric Institute (EEI), the National
Association of Regulatory Utility Commissions (NARUC), the Electric Power
Research Institute (EPRI), the American National Standards Institute (ANSI),
PEDCO Environmental Specialists, Inc., and several electric utility companies.
Attempts were made to gather reliability information from all known and
potential sources to obtain complete data for comparison of the various
systems. The final task was to organize, analyze, and compare the collected
data on utility and FGD systems using the comparison method developed in the
first task.
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SECTION 3
DESCRIPTIONS OF UTILITY EQUIPMENT AND FGD SYSTEMS
In this section, brief descriptions are presented of the electric
utility equipment and the FGD systems that were evaluated during this study.
The intent of the utility equipment descriptions is to provide an understand-
ing of the function of each of the equipment items and to illustrate how each
item fits into the overall electricity generating system. Since FGD systems
are very site-specific and are few in number within the United States, the
intent of the FGD system description is to highlight the differences between
the various installations. Differences in both process design and process
operations are discussed.
3.1 ELECTRIC UTILITY EQUIPMENT DESCRIPTIONS
The four major utility equipment items of interest to this study are
boilers, turbines, generators, and gas turbines. These items are currently
used by virtually every utility in the United States. Gas turbines are the
least common of these equipment items, although there are more than five
hundred gas turbines currently in operation.
There are two basic reasons for selecting these equipment items for
study. First, each is generally accepted by the electric power utility
industry as being commercially demonstrated technology. Second, data has
been recorded and in many cases is available concerning the reliability,
availability, and failure rates of each of these equipment items.
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Nuclear unit operating data is not included in this study because
nuclear units represent a portion of the electric utility industry in which
FGD systems will never be used. Thus a comparison of nuclear unit with FGD
system operating parameters will not clarify any portion of the present pro-
gram objectives. Additionally, the nuclear unit operating data is signifi-
cantly affected by regulatory constraints. These constraints can limit the
maximum output of a unit and significantly affect the downtime required for
inspection. These constraints have no counterpart for non-nuclear units or
FGD systems within the electric utility industry.
Modern electric power generating stations are complex units which
employ sophisticated mechanical, metallurgical, and electrical technology.
Figure 3-1 presents a highly simplified flow scheme which identifies the
general equipment categories important in this study. No attempt is made
here to distinguish between boiler types, equipment manufacturers, or equip-
ment design or quality. The primary reason for this is because most of the
reliability/availability data recorded are also in general categories.
The three major flowpaths shown in Figure 3-1 are water/steam, combus-
tion gas, and electrical. Many design constraints are placed on the equip-
ment which handle each of these flows. The following five sections briefly
describe the major equipment items mentioned above. The numbers in Figure
3-1 refer to the major equipment items discussed.
3.1.1 Utility Boilers
The principle of a modern water tube boiler is simple. The boiler
consists of steel drums or headers connected by a number of steel tubes, and
arranged in a furnace so that the hot gases have to pass through the bank of
tubes on their way to the stack. Hot combustion gases flow around the tubes,
transferring their heat to the water or steam within the tubes. The steam
in turn is collected and may be heated to a temperature well above the
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Induced
Draft
Fan
ESP
FLUE GAS
DESULFURIZATION
SYSTEM (6)
Jh~
To
Stack
TURBINESi
vo
Cooling
Water
Return
HP Feed
Water Heater
LP Feed
Water Heater
Condensate
Pump
Coo1tng
Water
Supply
Ash. Slag
Figure 3-1. Simplified flowscheme for an electric power generating station.
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saturation temperature (superheated) before being used. In other separate
portions of the boiler, steam which has been partially expanded through a
turbine may be reheated to a temperature very near the original superheat
temperature.
As steam flows out of the boiler it becomes necessary to replenish the
water that was evaporated. For this reason feed pumps are necessary to supply
water to the boiler. These pumps must operate at a pressure high enough to
overcome the pressure in the boiler. In the operation of any boiler, it is
essential always to keep water in the boiler. If the boiler should run low
on water, the tube metal would become hot, loose its strength and rupture.
At the same time, the boiler should not be filled to a point where there is
insufficient room for the steam to collect. Typically, level control devices
or steam and water flow devices are used to insure that the amount of water
entering the boiler equals the amount of steam leaving.
Boiler feed water is usually heated before being delivered to the boiler.
A feed water heater (using low pressure exhaust steam) or an economizer or
both are used to do this. An economizer is a separate bank of tubes through
which the feed water passes before it enters,the boiler. This bank of tubes
is placed between the boiler tubes and the air heater to absorb some addi-
tional heat from the combustion gases thus improving the economy of the
boiler.
Air is heated prior to introduction into burners in the boiler. The
incoming cold air is heated from the hot flue gas in an air preheater. Pre-
heating the air primarily improves the thermal efficiency of the boiler, but
also helps stabilize combustion in the burners and in pulverized coal firing,
is used to dry the coal during pulverization.
Air preheaters can be divided into two classes. Tubular air preheaters
are of fin tube construction and are generally used in industrial boiler
application^ and smaller utility boiler applications. The regenerative
10
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air preheater is generally in the form of a large wheel made of honeycomb
steel. The wheel slowly rotates. One sector of the wheel is exposed to the
flue gas and is heated. The heated section of the wheel then leaves the flue
gas duct and enters the combustion air duct. In the combustion air duct,
the hot honeycomb steel gives up its heat to the air. The wheel continues
to rotate and the cycle is repeated. Wheel rotation speeds are usually .05 to
5 rpm. The regenerative air preheater is more expensive and more efficient
than the tubular preheater. Thus the regenerative preheater is usually
applied to the larger and newer utility boilers.
Boilers used in utility applications can be classified into two cate-
gories based on the water/steam flow characteristics. These categories are
natural circulation and forced circulation. Natural circulation boilers
rely on the difference in density of the water and steam to establish and
maintain flow throughout the many portions of the boiler. Forced circulation
boilers rely on pumps to establish and maintain flow within the boiler.
Forced circulation boilers can be further classified into three subcate-
gories, i.e., controlled circulation, combined circulation and once through
units. A complete discussion of the features of each of these boilers can be
found in reference BA-185 and FR-P-287.
Natural circulation boilers comprise the largest number and the greatest
ranges of capacities and steam conditions now in use in the utility industry.
Natural circulation boilers invariably contain a steam drum. The steam drum
has many functions, but primarily serves as a space for the separation of
steam and water. The steam leaves the drum and the water is allowed to re-
circulate within the boiler.
Forced circulation boilers came into being in an effort to improve the
efficiency of energy conversion from fuel to steam and then to electricity.
Higher steam temperatures and subsequently higher pressures offer the poten-
tial of better cycle thermal efficiency. However, as the steam pressure
11
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increases the difference between the water density and steam density becomes
less, until at 3206 psia, the critical pressure, no difference in density can
be found. Thus the natural circulation boiler cannot be used and only forced
circulation boilers are feasible. Boilers which operate below 3206 psia out-
let steam pressure are called subcritical. Boilers operating above 3206 psia
are called supercritical.
Supercritical boilers are of the once through type and thus do not con-
tain steam drums. This boiler can be visualized as one long channel, cold
fluid (water) at one end and hot fluid (steam) at the other.
Subcritical .boilers constructed in accordance with each category dis-
cussed, i.e., natural and forced circulation, controlled, combined, and once
through exist in utility service.
3.1.2 Turbines
Turbines provide a means for converting energy in the steam into useful
shaft work. Simply stated, a turbine is a shaft mounted on two or more sets
of bearings. Attached to the shaft are a set of wheels or stages which have
blades attached to the rim. These blades, or buckets as they are commonly
called, are shaped such that the passage of steam forces the wheel to turn
thus turning the shaft. Stationary nozzles set between the rotating stages
direct the steam so that it continually drives the buckets.
Turbines are designed to turn at a fixed speed and are equipped with
automatic controls to accomplish this. The rotating turbine shaft is coupled
to an electric generator rotor which is the means for converting shaft work
into electricity.
Turbines can be classified in terms of the steam flow within the case.
In simplex turbines, the steam flows in one direction within the case, i.e.,
from one end to the other. In compound turbines, the steam flows in two or
12
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more directions within the case, i.e., steam is admitted at some intermediate
point along the length of the turbine, flows to one end, exits and is readmit-
ted to the turbine and flows in the other direction along the axis of the
turbine. Thus two simplex turbines are housed in one case.
As turbines become larger, more cases and rotors are required. The
cases and rotors can be arranged in series, in parallel or series-parallel.
If all rotors are connected and operate from a common shaft center line, the
unit is called tandem. If the rotor shafts are parallel, the unit is called
crossed. The most common turbine classifications in utility use are tandem-
compound and cross-compound. The two or more shafts of a cross-compound unit
may operate at the same or different rotational speeds, i.e., 3600/3600 or
3600/1800.
3.1.3 Generators
A generator consists of wire coils turning through the lines of flux
from a magnet. As the wire coil interrupts the magnetic flux lines a voltage
is produced in the wire, thus generating electricity. A central station
generator consists principally of a magnetic circuit, dc field winding, ac
armature, and mechanical structure including cooling and lubricating systems.
The steam turbine, coupled to the generator rotor, provides the shaft power
necessary to turn either the coil through the magnetic flux or to turn the
magnet within the coil.
Only one generator is normally coupled to a tandem turbine. Either one
or two generators may be coupled to a crossed turbine. Where two generators
are used, the generator is called a two-shaft generator. Two shaft generators
may in reality be two separate and distinct pieces of equipment but are lump-
ed together in common terminology within the utility industry.
13
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3.1.4 Condensers
The steam exiting the turbine is condensed to create a vacuum at the
turbine exhaust. The efficiency of the turbine is improved by allowing it
to exhaust into a vacuum rather than to the atmosphere. The condensing
steam can easily be returned to the boiler as feed water.
The condenser uses cooling water passing through a bank of tubes to cool
and condense the turbine exhaust steam. The steam condensate collects in a
"hot well" which serves as a reservoir for a pump returning condensate to the
boiler feed water heaters and boiler feed pump.
3.1.5 Gas Turbines
Gas turbines provide a means for obtaining shaft work directly from com-
bustion gases without the intermediate step of steam generation. Figure 3-2
illustrates a simple gas turbine cycle. The compressed, hot combustion gases
are used to drive the turbine rather than steam.
A gas turbine can be incorporated into a steam power plant in many ways.
These combined cycles are designed to suit each power plant's needs. The
turbine exhaust can be used as part of a boiler's combustion air or as a
source of boiler feed water preheat. More complex cycles can also be con-
structed. In many cases, gas turbines are operated to handle peak load condi-
tions.
3.2 FGD SYSTEMS
A significant portion of this study was devoted to ascertaining the
availability/reliability of operating lime/limestone flue gas desulfurization
systems. This investigation was limited exclusively to lime and limestone
systems for the following reasons: 1) lime/limestone FGD systems have been
14
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Ul
COMPRESSOR
FUEL
SHAFT
TURBINE
GENERATOR
COMBUSTION CHAMBER
Figure 3-2. Simplex-cycle gas turbine flowscheme.
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installed and operated on a commercial scale in the United States; 2) three
full scale (65 MW or larger) lime/limestone FGD systems have a relatively
long (greater than 3 years) operating history; 3) lime/limestone FGD systems
are considered commerical technology by the EPA; and 4) performance data for
six lime/limestone FGD systems are readily available.
3.2.1 General Lime/Limestone FGD Systems
The lime/limestone flue gas desulfurization process uses a slurry of
calcium oxide or calcium carbonate to absorb SOa in a wet scrubber. This
process is commonly referred to as a "throwaway" process because the calcium
sulfite and sulfate formed in the system are disposed of as waste solids.
Figure 3-3 illustrates a generalized lime/limestone slurry scrubbing system.
The gas flows from the boiler to the FGD system. Particulates in the
flue gas stream can be removed by the SOa scrubber or by auxiliary equipment
(e.g., an electrostatic precipitator) which processes the gas upstream of the
FGD system. FGD systems which do not have auxiliary particulate control
often employ a prescrubber designed to remove particulates from the gas just
upstream of the absorber.
The actual SOa absorber design varies from one application to the next.
These designs differ in S02 removal efficiency as well as operating relia-
bility. The SOa absorber designs can be classified in the following cate-
gories :
1) Venturi Scrubber
2) Spray Tower Scrubber (horizontal and vertical)
3) Grid Tower Scrubber
4) Mobile Bed Absorber
Flue gas enters the absorber and is contacted with a lime or limestone
slurry. This contact results in the absorption of SOa from the gas phase
into the liquid phase where the following chemical reactions occur.
16
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Figure 3-3. General lime/limestone FGD system.
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For Lime Systems:
S02(g) + CaO(s) + % H20 + CaS03 • % H20(s) (3-1)
For Limestone Systems:
S02(g) + CaC03(s) + lsH20 ->• CaS03 • ^H20(s) + C02(g) (3-2)
In both cases the major reaction product is calcium sulfite (CaSOa).
In addition to S02, some oxygen (02) is also absorbed from the flue gas.
This results in the oxidation of S02 and formation of calcium sulfate (CaSOi,)
(Equation 3-3). The formation of calcium sulfate can result in sulfate
scaling which is a problem that has plagued many of the operating lime/
limestone FGD systems.
-H-
Ca(aq) + S03(aq) + *s02(g) + 2H20 •* CaSOu • 2H20(s) (3-3)
The degree of oxidation of sulfite to sulfate can vary considerably,
normally ranging from near zero up to 40 percent in utility boiler applica-
tions . In some systems treating dilute S02 gas streams, sulfite oxidation
has reached 90 percent. The acutal mechanism for sulfite oxidation is not
completely understood. The rate appears to be a strong function of oxygen
concentration in the flue gas and liquor pH. It may also be increased by
trace quantities of catalyst in fly ash entering the system.
The feed material for a lime scrubbing process is usually produced by
calcining limestone. Feed for a limestone process generally comes directly
from the quarry, and is then reduced in size by crushing and grinding. The
lime or limestone is mixed with water to form a slurry which is used to
absorb S02.
Flue gas which exits the S02 absorber enters a mist eliminator where
droplets of slurry entrained in the flue gas are removed. The flue gas is
then reheated and exhausted to the atmosphere through the stack.
18
-------
The lime/limestone slurry exiting the absorber contains both calcium
sulfite and calcium sulfate. This spent slurry is routed to the effluent
hold tank which is the point of addition for the lime/limes tone feed slurry
(Figure 3-3).
The hold tank is essentially a reaction vessel for the precipitation of
calcium sulfite and calcium sulfate solids. The tank is designed to allow
adequate residence time for the precipitation reactions to occur. Too short
a residence time in the hold tank can result in scaling of the absorber.
A continuous stream of 10 to 15 percent solids is recycled to the
absorber from the effluent hold tank. In addition, a purge stream is contin-
uously withdrawn from the hold tank for treatment and disposal. This serves
to remove calcium sulfite/sulfate solids from the system.
In some applications with an on site disposal pond, solids may be pumped
directly from the effluent hold tank to the pond. In closed loop operation,
overflow liquor from the pond would then be returned to the FGD system for
reuse.
Some installations employ dewatering equipment to minimize the pond area
required for sludge disposal. Depending on the physical properties of the
solids produced in the FGD system, a thickening device such as a clarifier
can be used to increase the solids content to a maximum of about 40 weight
percent. Additional dewatering to 60 to 70 percent solids can sometimes be
achieved by vaccum filtration. Forced oxidation techniques can be used to
produce a sludge with up to 80 percent solids.
Sludge disposal is an integral part of lime/limestone FGD systems. The
quantity of sludge produced is large in both weight and volume, and requires
a large waste pond or landfill area for disposal. On site sludge disposal
is usually performed by sending the waste solids to a large pond. Settling
19
-------
of the solids occurs and pond water is recycled back to the process hold
tank for reuse. "Stabilization" methods are currently under development to
convert the sludge to structurally-stable, leach-resistant, landfill material.
These methods could be used when on site disposal is not possible. The
stabilized material can then be trucked to an off site area for landfill.
3.2.2 Specific Lime/Limestone Systems
An initial screening of PEDCo's Bi-Monthly Status Report-Flue Gas
Desulfurization Systems identified 30 operational FGD systems. Of these 30
systems 17 are lime or limestone slurry scrubbing processes. However, 5 of
the 17 lime/limestone systems are treating flue gas from units under 50 MW in
size. In addition, long-term (greater than 1 year) performance data does not
exist for 6 of the 12 systems treating flue gas from units larger than 50 MW.
As a result of this screening process, the following 6 FGD systems were
identified as best suited for detailed study.
1) Arizona Public Service Company's Cholla Generating
Station - Unit No. 1
2) Commonwealth Edison Company's Will County Station -
Unit No. 1
3) Duquesne Light Company's Phillips Station
4) Kansas City Power and Light Company's LaCygne Station
5) Kentucky Utilities Company's Green River Station
6) Louisville Gas and Electric Company's Paddy's Run
Station - Unit No. 6
A brief description of each of these 6 systems appears in Appendix D.
20
-------
SECTION 4
COMPARISON BASIS
Many parameters are currently being used to report the performance of
electric utility equipment and FGD systems. These parameters may have the
same name but different definitions from one data reporting system to another.
Additionally, there is no one parameter within the existing data bank that
can be used directly for comparison and ranking of dissimilar pieces of
equipment or systems.
In an attempt to directly compare the relative performance of FGD systems
and utility equipment components a Figure of Merit was developed. This par-
rameter incorporates such factors as reliability, development status, and
repair effort; and results in a single statistic which can be used to compare
different processes. The following sections describe the development and use
of the Figure of Merit.
4.1 DEVELOPMENT OF THE COMPARISON BASIS
The need for a method of comparison which would permit the relative
performance of utility equipment and FGD systems to be compared on an equi-
valent basis became evident early in the conduct of this study. In develop-
ing a comparison basis or Figure of Merit, the following goals were
established.
1) Existing data should be applicable to the comparison technique.
2) New data, if required, should not be too difficult to obtain.
21
-------
3) The comparison technique should be relatively simple to
compute and apply.
4) The comparison technique should include at least:
a) A measure of availability
b) A measure of maintenance/economic requirements
c) Scale-up or learning function
These goals then define the type of comparison to be formulated. In addition,
these goals define a tool which has present usefulness rather than theory
which may never have sufficient data for application, except possibly for
historical value.
Existing data should be used where available and applicable. This
premise was established such that a whole new data base was not required.
The primary thrust of the comparison technique is to illuminate present dis-
cussions with existing data. A comparison technique which must wait months
or years for the start of data acquisition, and then longer before meaningful
interpretations could be obtained, was to be avoided if at all possible.
Any new data which is required to complete the comparison must be
obtainable without creating additional difficulties for the reporting or
collecting agencies. New data requirements could come from two possible
directions. The equipment operating logs may contain some of the needed
information. Data not now recorded may have to be added to the data require-
ment list of selected installations. In either case, the collection and
reporting of new data requirements will be minimized and will not require
the addition of sensing or logging equipment.
The comparison technique must be relatively simple to compute and apply.
Preferably no more than a desk calculator will be required for computational
22
-------
purposes. The comparison need not have physical meaning, such as service
hours, etc., but must at least represent a coefficient of performance and
must display a spread or ranking within which each component or system can
be easily evaluated or ranked.
The preceding discussion describes the functional requirements of the
comparison technique. There are three specific requirements which must be
added to the functional requirements; namely, a measure of "availability,"
a measure of the maintenance/repair effort required to achieve a given equip-
ment performance, and a learning function.
Historically, "availability" is a term which has been used to describe
the percentage of time a piece of equipment is ready to perform a specific
task. Several different types of availability are currently being used and
erroneously being compared one to another within the electric utility indus-
try. These definitions primarily differ in what is meant by the term "ready."
The comparison technique must contain a term which measures the "availability"
of a piece of equipment without being ambiguous, yet meeting the functional
requirements of the existing data systems.
An alternate approach to measure "availability" has been taken in the
comparison technique to overcome the many definitions of "ready." This
approach is to measure "availability" as the time a piece of equipment will
operate before it is forced to shut down despite an existing operating
schedule, (i.e., the operating time between forced outages). Mathematically
this approach will be described in greater detail in the following section
and in Appendix A. This measure of availability is, however, not sufficient
by itself to complete a meaningful comparison.
The effort required to achieve a given performance from a piece of
equipment is as important as the given performance itself. Utility equipment
which requires constant attendance is significantly less attractive than
23
-------
equipment which runs forever without repair or attendance. In the real world,
operating equipment usually lies somewhere between no attention and constant
attention. It is a measure of the attention expended to achieve performance
which the comparison technique must include.
A term which includes a learning curve or learning function should be
included. A learning function has for years been applied to manufacturing
operations, design adequacy, student repetition, etc., to allow for time
necessary to reach proficiency. A similar analogy is just as applicable to
the design of utility equipment, the design of a utility plant, the instal-
lation or construction of the equipment or plant, and the equipment or plant
operation. Near the completion of a project, personnel involved with each
of these areas will normally admit that if they were to do the project again,
modifications or changes would be made to improve the product. This is the
learning curve as applied to the comparison technique.
Unfortunately, many of the major components and many of the station
designs are one of a kind. Historically, this has been the nature of the
utility business. Only recently (within the past 5 years or so) has the
concept of a baseline central station electric plant, modified for specific
site requirements, come into being. Thus, the learning curve for major
components and for plant design has been generally limited to less than 5
replications by any individual vendor, designer, constructor, or operator.
The fifth replication can, however, represent a significant operational
improvement over the first if sufficient time elapses between each replica-
tion for intelligent modifications to be applied and tried.
A corallary to the benefit achieved from the learning curve, is the
concept that some modifications can economically be incorporated into the
first model reflecting beneficial changes incorporated in later replications.
However, in most cases, the first model will never achieve the operating
characteristics of the later models.
24
-------
The learning function must become an integral portion of a comparison
model. To compare the operating characteristics of a fifth model or replica-
tion to a first of its' kind edition must account for an anticipated learning
function.
4.2 MODEL DESCRIPTION
The comparison model or Figure of Merit incorporates the following
elements:
a) Existing data is applicable.
b) New data, if required, is not difficult to obtain.
c) The comparison technique is relatively simple to
compute and apply.
d) The comparison technique includes the following:
1) "Mechanical availability
2) Maintenance/economic measure
3) Scale-up or learning function
The comparison m< : 1 Computes » Figure of Merit from a three term
equation. The first term in the equation is a measure of the probability
of being operational at the end of a time period without "failure." The
second term is a measure of the effort expended in completing a repair. The
third term is a learning function which accounts for the number of replica-
tions of a unit or equipment item.
25
-------
In mathematical terms the comparison model is:
Figure of f ,, H>T
Merit =6XP
II III
where X = The reciprocal of the mean time between full forced
outages (1.0/hr).
t = Time period to be considered, (nominally 720 hrs in
this study).
= The reciprocal of the mean time to repair a forced
outage (1.0/hr).
T = Time period allowed for repair of an outage before a
failure is declared. (60 hrs in this study)
e = 2.718, the base of natural logarithms.
RMA = Relative Mechanical Availability, %, as defined by
the Edison Electric Institute and set forth in
Appendix A to this report.
i = The number of replications of a piece of equipment or
plant. A replication is further restricted such that
sufficient time is available to try one model and
incorporate changes in the next prior to placement
into service.
The Roman numerals designate the three terms in the Figure of Merit
equation.
Term I defines the probability that a piece of equipment (or plant) will
be functioning at the end of time period t with the additional constraint
that repairs are allowed, but no repair or maintenance action requiring
longer than T hours to complete is operationally permissible. Term II,
Relative Mechanical Availability (RMA), is a form of operating availability
adjusted to show relative effort expended to reduce outage time. Term III
is a derived learning function. A detailed derivation of each of these terms
26
-------
is presented in Appendix A to this report. Only a discussion of the
reasoning and the limitations will be presented in this portion of the report.
4.3 MODEL DISCUSSION
The Figure of Merit, calculated by the formula presented in Section 4.2
of this report, has no physical significance by itself. The number calculated
should not be interpreted in any manner other than a relative number used for
comparison of one piece of operating equipment to another. Terms I and II
do have physical significance as individual terms, their product does not.
Each of the terms in the computation of the Figure of Merit fulfills
one of the design objectives set forth in Section 4.1, objective (4). The
combination of these terms in product form was selected such that equal
weight is given to each of the three areas of concern.
4.3.1 Discussion of Term I
The first term in the Figure of Merit equation comes from the relia-
bility theory. A detailed derivation of this term can be found in Appendix A
to this report. The portion of the term, e , is the "reliability" or the
probability that a piece of equipment will be functioning at the end of a
specified time period, t. However, the demand for electical generation
capacity fluctuates on daily, weekly, monthly, and yearly cycles. This
demand, coupled with other system parameters suggests that there are periods
of time wherein repairs and maintenance are permissible without sacrifice
when a piece of equipment does not function during the entire time period, t.
Thus, the concept arises that "reliability" can be modified to permit repairs
and maintenance which do not exceed a given repair time, T. The second
exponential in Term I, e , performs the modification to the "reliability"
to permit limited repairs or maintenance. Term I, thus, defines the proba-
bility that a piece of equipment will be functioning at the end of time
27
-------
period t, or that it can be repaired or maintained in time T and returned to
a functional status. This definition and approach approximates the real
behavior and operation of equipment used in the electric utility industry.
Equipment which requires cyclic short-term maintenance such as zeolite
bed regeneration for 2 hours every 24 hours is not classified "unreliable."
Likewise, the spreader stoker which breaks a connecting link two or three
times a month but which can be repaired in 30-minutes is by this defini-
tion not classified "unreliable." These are problems with which each utility
must contend and face, but do not enter into this comparison model.
The characteristic time X, the reciprocal of the mean time between full
forced outages, has been selected to be identical with the definition set
forth by the Edison Electric Institute (EEI) (ED-058) and reported in their
annual Equipment Availability Report compiled by the Prime Movers Subcom-
mittee. By EEI definition, a forced outage is "the occurrence of a compon-
ent failure or other condition which requires that the unit be removed from
service immediately or up to and including the very next weekend." The mean
time between full forced outage was intentionally selected as the character-
istic operating time rather than the mean time between partial forced outages.
The data reporting and collection network for full outages appears to be
much more accurate and complete than the data for partial forced outages.
The parameter , the reciprocal of the mean time to repair or restore
a full forced outage, was selected to be identical with the EEI definition
of forced outage hours. This selection was made following the same line of
reasoning as was used to select the mean time between full forced outages
with the additional constraint that the mean time to repair and the mean
time between failures should be based on the same definition of "failure"
or malfunction.
28
-------
4.3.2 Discussion of Term II
Term II, Relative Mechanical Availability, in the Figure of Merit
equation is an EEI defined term. This is a form of operating availability
adjusted to show the relative effort needed to repair equipment which is in
an outage status. One of the prime assumptions in deriving this term is that
outage time is predominately affected by work schedules and crew sizes.
Relative Mechanical Availability (RMA) uses manhours worked as a measure of
effort. This effort is reasonably independent of work schedules. A detailed
discussion of RMA is presented in Appendix A to this report.
4.3.3 Discussion of Term III
Term III in the Figure of Merit computation is a measure of the benefit
which may be obtained from replications of a given equipment type or of a
given plant design. The learning function is empirically derived from exist-
ing utility data. Some adjustment in the exponent may be warranted as addi-
tional data becomes available.
The highest difficulty in applying the learning function is to determine
what constitutes a "new" model and what constitutes an "improved" model.
The following definition will help overcome this difficulty. An improved
model must be sufficiently later than the new model in time to permit the
incorporation of changes which result from experience gained in any or all
three of the following areas: manufacture, installation, and operation.
Ideally, information from all three areas will be incorporated into an
improved model.
29
-------
SECTION 5
UTILITY COMPONENT OPERATING DATA
Performance data for equipment used in the electric utility industry
have been collected on a continuing basis since 1965. There are at least
four major data banks within the United States, each with its own defini-
tions, data reporting systems and areas of interest. These systems conflict
with each other and duplicate many areas, and as an aggregate sum, do not
provide sufficient information in a form useful to this study.
An ad hoc steering committee has been set up by the American National
Standards Institute to coordinate a data gathering effort. A consistent
format is being developed for reporting and disseminating reliability data
on equipment used in both the fossil and nuclear portions of the electric
utility industry. Additionally, EPRI has several programs underway to
define data needs. The existence of these programs highlights the present
state of flux of the electric utility operating performance data acquisition
and dissemination systems.
5.1 DEFINITION OF TERMS
Unless specifically stated otherwise, the terms used in this section
are in accordance with the Edison Electric Institute (EEI) standard
definitions.
Available; The status of a unit or major piece of equipment which
is capable of service, whether or not it is actually in service.
30
-------
Availability; The fraction of time that a unit or major piece of
equipment is capable of service, whether or not it is actually in
service.
Forced Outage: The occurrence of a component failure or other
condition which requires that the unit be removed from service
immediately or up to and including the very next weekend.
Forced Outage Hours (FOH); The time in hours during which a
unit or major equipment was unavailable due to a forced outage.
Forced Outage Rate (FOR); The ratio of forced outage hours
divided by service hours plus forced outage hours expressed
as a percentage. FOR = FOH/(SH + FOH) x 100
Relative Mechanical Availability (SMA); Relative Mechanical
Availability is a form of availability adjusted to show rela-
tive maintenance effort. A more complete definition is pre-
sented in Appendix A.
5.2 SOURCES AND AVAILABILITY OF DATA
There are four primary systems in operation in the United States which
collect and report utility system performance data. These systems are the
Edison Electric Institute (EEI) Prime Movers Committee; the Nuclear Plant
Reliability Data System (NPRDS) under the direction of the American National
Standards Institute (ANSI) subcommittee N18-20; the Gray Book I, issued by
the Nuclear Regulatory Commission (NRC Gray Book); and the Federal Power
Commission (FPC). The FPC publishes special reports on many different facets
of the electric utility industry but does not issue routine reports on equip-
ment components. The NRC Gray Book publishes performance data on the reactor
systems for nuclear plants.
31
-------
The NPRDS System is concerned with reliability-type data for the
components in the nuclear safety systems of nuclear central station electric
units. The EEI data is the only major data bank which is directly applicable
to this study (i.e., major utility equipment performance data ). These data
are published in the EEI Prime Movers Committee Reports (ED-058).
In addition to the four data sources previously mentioned, equipment
performance data are scattered throughout the open literature, in many
different journals, and in government reports. Most notable of the latter
is WASH 1400, Reactor Safety Study-An Assessment of Accident Risks in U.S.
Commerical Nuclear Power Plants (US-391). Additional data are recorded and
maintained by many individual utilities, and by insurance companies. Much
of the data in the open literature were not applicable to this study because
of the short time spans reported or because of incomplete data sets. Insur-
ance Company data covers only major outages above the policy deductibles and
does not contain operating time, thus is not useful in this study.
It became evident that the EEI reports contained the longest time span
of relevant data for the purposes of this study. EEI was commissioned to
perform a computer search of their data base to provide Radian with year-by-
year performance data of the information published in their ten year equip-
ment availability summary. The results of this search are presented in
Section 5.3.1.
5.3 UTILITY DATA PRESENTATION
The majority of performance data for electric utility component equip-
ment presented in this section was obtained from three sources: 1) EEI
reports and commissioned EEI data searches, 2) private utility files, and
3) the open literature. The EEI data presented such parameters as mean time
between full forced outages, mean time to repair full forced outages, and
32
-------
relative mechanical availability. The private utility files provided only
"availability" data. The open literature provided isolated data points,
which could be applied only after careful verification of the definition of
terms and their application.
The data necessary to describe existing electric utility system equip-
ment, to the degree necessary for a meaningful comparison with FGD systems,
exists within the EEI data system. The first search from this data bank was
extremely useful, but did not provide all the requirements for this compari-
son. The data needed to address the "learning curve" hypothesis for the
various utility equipment components was obtained in a second search.
In addition to the above sources, some data were excerpted from the
technical literature to illustrate the effects of an apparent "learning
curve." These data are for specific units of one utility and represent
essentially one system design duplicated three times.
5.3.1 EEI Data Summary
EEI Data are presented for controlled circulation boilers, once-through
circulation boilers, single shaft generators, tandem compound and cross
compound turbines, and gas turbines. Data for the first five equipment items
are presented from a special data search. The gas turbine data are from the
annual equipment availability report of the Prime Movers Committee.
Operating data for controlled circulation boilers along with computed
parameters, such as Term I and the product of Term I and II of the Figure
of Merit are presented in Table 5-1. Controlled circulation boilers repre-
sent some of the oldest integral pieces of equipment used in central electric
generating stations. In general, this equipment has an excellent performance
history. The Term I-Term II product of the Figure of Merit is better than
50 for 390 MW and larger size boilers. The mean time between full forced
outages is nominally longer than 1000 hours, whereas the mean time to repair
33
-------
TABLE 5-1. OPERATING STATISTICS OF CONTROLLED CIRCULATION BOILERS
Years'
Service
Units 'Oper1
in Avail
Service %
MTBFFO1'2
Hrs
RHA1'3
7.
RMA1
Units
390 MW Thru 599 MW
1
2
3
4
5
6
7
8
9
10
600 + MW
1
2
3
4
5
6
7
8
9
10
25
30
28
27
27
23
16
13
13
9
8
9
9
6
4
3
2
1
1
1
83.
87.
87.
87.
85.
86.
85.
81.
81.
81.
89.
80.
85.
86.
76.
77.
84.
75.
99.
88.
2
8
5
5
2
6
1
4
5
2
9
6
8
0
0
0
6
4
1
3
1441.10
1355.4
1371.5
1344.4
1051.6
950.8
834.9
843.9
572.6
691.8
762.0
1159.8
1066.1
1460.7
1523.5
1051.2
1096.5
486.7
2190.0
1752.0
88.7
81.9
86.6
70.6
63.5
86.9
65.1
48.7
79.1
81.5
84.6
86.9
93.4
71.7
75.7
99.4
--
--
_-
~—
14
19
18
16
15
13
11
7
4
1
4
3
3
2
2
1
0
0
0
0
• "FOH1 ' 5N
-------
a full forced outage is less than 70 hours with one exception, the 600 Mw-and-
above size class in its fifth year of service. These data indicate that,
on the average, a controlled circulation boiler will operate for 42 days
without experiencing a full forced outage and repair of the outage will take
less than 3 days.
Operating statistics for once-through circulation boilers are presented
in Tables 5-2 and 5-3. Once-through circulation boilers represent a much
newer boiler type than the controlled circulation boiler. Supercritical
boiler operating data are presented in Table 5-2 and subcritical operating
data are presented in Table 5-3.
Once-through boilers represent the majority of new 390 MW and larger
units which are currently being installed. This is illustrated by the
number of once-through boilers which were in their tenth year of service (7)
as compared to the number that were in their first year of service (94). The
Term I-Term II product of the Figure of Merit of once-through boilers: is
50 or greater with the exception of the 600 MW-and-above subcritical size of
boiler. Based on the number of units reporting data, the once-through sub-
critical boiler represents a piece of equipment the utility industry has
tried and has not accepted. (This boiler configuration was rejected for
both operational and economic means.) The mean time between full forced
outages is greater than 610 hours with three exceptions; the 600 MW-and-above
subcritical class for the eighth, ninth, and tenth year of operation. The
mean time to repair a full forced outage of a once-through boiler is nominal-
ly 80 hours. These data indicate that, on the average, a once-through boiler
will operate 25 days without a full forced outage, and repair of the outage
will take just over 3 days.
Single shaft generator operating statistics are presented in Table 5-4.
The nominal Term I of the Figure of Merit for these generators is greater
than 93. The mean time between full forced outages is greather than one
35
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TABLE 5-2. OPERATING STATISTICS OF ONCE-THROUGH SUPER CRITICAL BOILERS
CO
Year*1
Service
Units1
In
Oper'
Avail
MTBFFO1'1
Hrs
RMA
7.
l i J
RMA1'
Units
Service T,
390 MW
1
2
3
4
5
6
7
8
9
10
Thru 599
36
37
34
35
38
34
28
18
8
3
MW
86.8
86.8
83.3
85.3
80.9
79.9
83.3
84.3
80.1
83.9
1181.9
1467.6
1342.1
1267.9
1359.7
1273.2
1370.4
1336.9
1208.3
1194.5
91.
91.
86.
95.
90.
85.
72.
86.
90.
--
8
3
7
8
0
6
1
6
8
22
24
18
15
13
5
2
4
3
0
"FOB1 ''No. FO1''
Hrs/ Occur 's
Yrs per Yr.
301.5 7
292.8 6
405.8 7
538.0 7
572.1 6
583.8 7
518.7 6
423.3 7
402.7 7
505.5 7
MTTRFFO7
Hrs
43
49
58
77
95
83
86
60
57
72
Figure of
Term I
.860
.866
.826
.771
.755
.760
.770
.820
.812
.770
Merit'
Term Ixll
78.
79.
71.
73.
68.
65.
55.
71.
73.
9
1
6
9
0
1
5
0
7
600 + MW
1
2
3
4
5
6
7
8
9
51
46
40
32
17
11
6
3
1
83.7
83.9
83.8
81.0
82.4
72.8
79.2
92.9
77.1
716.8
992.9
825.0
776.7
702.7
688.5
730.0
1095.0
876.0
79.
84.
72.
84.
81.
--
--
--
— -
1
1
9
9
6
'Reported by EEI for special request.
2HTBFFO-Mean tine between forced outage.
'RMA-Relatlve nechanlcal availability
''RMA Units-Number of units which reported
DMA data.
19
15
8
5
1
0
0
0
0
632.0 12
580.6 9
752.9 11
837.5 11
770.2 12
677.2 13
626.8 12
348.5 8
425.1 9
5FOH-Forced outage hours
53
64
68
76
64
52
52
44
47
per year.
.723
.753
.697
.655
.669
.719
.733
.845
.795
57.
63.
50.
55.
54.
—
—
--
--
*No. FO-thmber of forced outage occurences per year
7MTTRFFO-Mcan time to repair a full forced outage -
:Terms in computation of figure of merit from
2
3
8
6
6
' FOB
No. FO Occur
Section 4.0 of this report.
-------
TABLE 5-3. OPERATING STATISTICS OF ONCE-THROUGH SUBCRITICAL BOILERS
Years1
Service
390 MW
1
2
3
4
5
6
7
8
9
10
Units1 Oper*
in Avail
Service 7,
Thru 599
3
3
2
2
2
2
2
2
2
1
84.0
83.8
81.3
79.8
91.3
85.0
85.1
81.9
84.3
63.0
MTBFFO ' ' z
Hrs
1194.
797.
1347.
1460.
1347.
1952.
2920.
8760.
922.
798.
5
1
7
0
7
0
0
0
1
5
RMA3 ' 3
89.5
88.4
78.5
83.0
95.0
85.9
87.7
76.8
89.7
--
RMA1 '
Units
2
2
1
2
2
2
2
1
2
0
11 FOH ' ' 5 NaFO ' ' "
Hrs/ Occur 's
Yr per Yr
462.1
393.1
464.2
192.4
135.6
287.7
132.3
44.3
511.1
983.1
7
11
6
6
6
4
3
1
9
10
MTTRFFO *
Hrs
66
36
77
32
23
72
44
44
57
98
Figure
Term I
.784
.843
.783
.927
.961
.852
.939
.979
.761
.613
of Merit8
Term IxII
70.2
74.5
61.5
76.9
91.3
73.2
82.4
75.2
68.3
—
600 + MW
1
2
3
4
5
6
7
8
9
10
4
6
5
5
5
4
4
3
2
2
68.9
73.7
83.7
77.1
78.6
78.1
65.8
69.7
75.9
73.3
974.
1546.
1018.
1043.
843.
614.
661.
597.
501.
473.
0
0
6
4
7
7
1
3
9
5
47.6
48.9
72.6
51.3
70.4
49.0
12.8
64.9
--
•* —
2
4
4
3
2
2
2
2
0
0
312.3
659.6
544.2
470.6
546.6
599.0
748.8
1068.7
957.1
1410.9
9
6
8
8
10
14
13
14
17
18
35
110
68
59
55
43
58
76
56
78
.875
.764
.764
.779
.751
.748
.679
.578
.611
.494
41.7
37.4
54.2
40.0
52.9
36.7
8.7
37.5
--
"
'Reported by EEI for special request.
2MTBFFO-Mean time between full forced outage.
3RMA-Relative mechanical availability.
••RMA Units-Number of units vhich reported RMA data.
5FOH-Forced outage hours per year.
8No. FO-Number of forced outage occurences per year,.
7HTTRFFO-Mean time to repair a full forced outage =- =7—7:
• f _- t f HO. rU IJCCUr .
"Terms in computation of figure of merit from
Section 4.0 of this report.
-------
TABLE 5-4. OPERATING STATISTICS OF SINGLE SHAFT GENERATORS
Years '
Service
390 MW
1
2
3
4
5
6
7
8
9
10
Units '
in
Service
Oper1
Avail
HTBFFO '
Hrs
,2 FOH1' 3
Hrs/
Yrs
No. FO1 '
Occur' s
per Yr.
''MTTRFO5
Hrs
Figure of6
Merit
Term I
Thru 599 MW
67
72
56
54
51
41
29
19
8
3
94.0
93.8
91.2
95.4
92.9
94.9
95.7
93.0
99.6
79.2
9625.6
15777.0
18878.8
26296.0
17191.4
21134.1
28232.0
20808.0
35040.8
65700.0
38.0
44.3
123.8
27.5
17.2
33.0
3.6
3.7
0.5
51.1
1
1
0
0
0
0
0
0
0
1
38
44
--
--
--
—
--
--
—
51
.985
.988
.962
.973
.959
.966
.975
.966
.980
.967
600 + MW
1
2
3
4
5
6
7
8
54
48
40
30
16
9
4
1
90.2
90.3
95.1
93.9
95.1
94.3
99.2
100.0
9457.7
9247.5
14608.0
21906.0
15576.0
13140.0
8760.0
8760.0
174.9
293.1
82.9
172.9
72.4
17.4
14.4
0
1
1
1
0
1
1
1
0
175
293
83
173
72
17
14
--
.941
.933
.976
.977
.980
.998
.999
.921
'Reported by EEI for special request.
2MTBFFO-Mean time between full forced outage.
3FOH-Forced outage hours per year
"No. FO-Number of forced outage occurrences per year.
5MTTRFFO-Mean time to repair a full forced outage -
'Terms in computation of figure of merit from
Section 4.0 of this report.
FOH
No. FO Occurrences
38
-------
year, and the mean time to repair a full forced outage is less than 65 hours.
These figures indicate that both the 600-MW-and-above class and the 390-MW-
through-599-MW class single shaft generators should operate for a year with-
out incurring a full forced outage.
The operating statistics for the tandem compound and cross compound tur-
bine are presented in Table 5-5, 5-6, 5-7, and 5-8. Subcritical and super-
critical turbines are included in both classes. Term I of the Figure of Merit
of both classes of turbines is greater than 83. The mean time between full
forced outages is longer than 6 months with an average repair time of four
and one half years.
Term II in the Figure of Merit was not available for these turbines, and
consequently the product of Term I and II is not reported.
The performance data on gas turbine units reported by EEI is presented
in Table 5-9. No distinctions are made by EEI concerning the gas turbine
size or age. The EEI data is probably weighted toward smaller, older gas
turbines. The most recently reported availability for this class of equip-
ment is 89.0 percent (ED-043).
Availability data were obtained from a private utility for several gas
turbine units according to unit age. These data are plotted in Figure 5-1.
As can be seen from ftis graph, the Term I-Term II product of the Figure of
Merit for gas turbines is greater than 70 and the turbine availability tends
to level off at approximately 90 percent after three or four years of opera-
tion. These figures are in agreement with the data reported by EEI.
In addition to the above data, the EEI annual report contained perfor-
mance data on condensers. These data were not represented in tabular form
because all data showed the condensers to have extremely high availabilities.
The nominal mean time between full forced outages for this component was on
the order of 2 to 3 years.
39
-------
TABLE 5-5. OPERATING STATISTICS OF TANDEM
COMPOUND SUBCRITICAL TURBINES
Years l
Service
Units1 Oper1
in Avail
Service 7.
MTBFTO1
Hrs
•2 FOHll> No. FO"
Hrs/ Occur 's
Yrs per Yr.
MTTRFFO* Figure of8
Hrs Merit
Term I.
390 MW Thru 599 MW
1
2
3
4
5
6
7
8
9
10
600 + MW
1
2
3
4
5
6
7
8
32
36
28
25
22
16
11
10
7
4 '
13
13
11
8
7
4
3
1
87.0
89.0
92.2
89.7
88.8
92.4
86.2
92.7
93.3
84.0
84.4
84.5
88.2
89.0
91.7
91.0
93.3
100.0
3549.0
3756.6
6294.2
4762.4
3933.6
4524.4
10712.0 '
12517.7
8760.0
3187.6
2712.6
3452.4
5669.6
6375.3
12268.8
3504.0
2920.0
8760.0
291.5
103.0
66.3
191.3
132.0
112.1
7.8
87.7
14.1
67.0
247.5
227.0
34.3
148.1
8.4
13.8
81.7
0
2
2
1
2
2
2
1
1
1
3
3
2
1
1
1
2
3
0
146
52
66
96
66
56
8
88
14
22
83
114
34
148
8
7
27
~ "
.874
.941
.955
.922
.929
.947
1.00
.971
.999
.985
.879
.884
.978
.927
1.00
1.00
.974
.921
'Reported by EEI for special request.
2MTBFFO-Mean time between full forced outage.
3FOH-Forced outage hours per year.
"No. FO-Number of forced outage occurrences per
*MTTRFFO-Mean time to repair a full forced outage
'Terms in computation of figure of merit from
Section 4.0 of this report.
FOR
No. FOUccurrences
40
-------
TABLE 5-6. OPERATING STATISTICS OF TANDEM
COMPOUND SUPER CRITICAL TURBINES
Years1 Units1
Service in
Service
390 MW Thru 599
1
2
3
4
5
6
7
8
600+ MW
1
2
3
4
5
6
7
8
32
32
26
28
28
24
18
9
42
36
30
22
9
5
1
2
Oper1
Avail
%
MW
85.8
82.3
87.4
93.8
88.3
90.6
87.8
89.8
89.0
86.6
93.8
92.0
83.1
94.2
64.9
93.6
MTBFFO ' ' 2
Hrs
4007.0
4065.0
5556.9
5987.7
5578.4
5392.0
5437.2
8760.0
2673.2
3219.2
4174.1
3323.2
3583.6
7300.0
1752.0
2502.9
FOH1 • 3 No. FO"
Hrs/ Occur 's
Yr per Yr.
413.5
359.5
514.9
50.4
110.9
36.4
125.8
190.3
197.4
276.9
97.5
313.1
488.1
4.6
70.3
124.9
2
2
2
1
2
2
2
1
3
3
2
3
2
1
4
3
MTTRFFO5 Figure6
Hrs of Merit
Term I.
207
180
257
50
55
18
63
190
66
92
49
104
244
5
18
42
.874
.881
.902
.964
.958
.995
.950
.942
.897
.890
.951
.885
.855
1.00
.985
.933
'Reported by EEI for special request.
2MTBFFO-Mean time between full forced outage.
3FOH-Forced outage hours per year.
*No. FO-Number of forced outage occurrences per year.
5MTTRFFO-Mean time to repair a full forced outage *
6Terms in computation of figure of merit from Sec. 4.0
of this report.
FOH
No. FO Occur.
-------
TABLE 5-7. OPERATING STATISTICS OF CROSS
COMPOUND SOBCRITICAL TURBINES
Years ' Units l
Service in
Service
Oper1
Avail
7.
MTBFFO1'2
Hrs
FOH1 ' 3
Hrs/
Yrs
No. FO"
Occur1 s
per Yr
MTTRFFO5 Figure6
Hrs of Herit
Term I.
390 MW-599 MW
1
2
3
4
5
6
7
8
9
10
600+ MW
1
2
3
4
5
6
7
8
9
10
5
8
7
10
11
11
11
9
10
9
1
3
3
3
3
3
3
3
3
3
79.2
91.0
90.6
92.9
92.0
96.1
91.0
87.2
90.8
83.9
93.7
91.9
85.8
90.1
78.0
89.2
81.6
80.4
89.9
88.5
10956.0
6373.1
6816.0
12517.7
8036.0
8036.0
6888.0
15772.9
2504.9
5394.5
2190.0
5256.0
26304.0
26280.0
26328.0
5256.0
6576.0
5256.0
8776.0
26280.0
25.2
126.8
150.6
9.6
95.9
17.0
40.8
2.3
61.6
40.4
274.0
129.3
0
0
0
189.3
147.5
280.7
215.1
0
1
1
1
1
1
1
1
0
3
2
3
1
0
0
0
1
1
1
1
0
25
127
151
10
96
17
41
--
20
20
91
129
--
--
--
189
148
281
215
~ ~
.994
.932
.931
1.00
.953
.997
.976
.955
.986
.993
.844
.918
.973
.973
.973
.905
.930
.895
.940
.973
'Reported by SEI for special request.
2MTBFFO-Mean time between full forced outage.
3FOH-Forced outage hours per year.
"No. FO-Number of forced outage occurrences per year.
5MTTRFFO-Mean time to repair a full forced outage
6Terms in computation of figure merit from
Section 4.0 of this report.
42
-------
TABLE 5-8. OPERATING STATISTICS OF CROSS COMPOUND
SUPER CRITICAL TURBINES
Years1 Units1 Oper '
Service in Avail
Service %
MTBFFO1'2 FDH1' 3 Na FO"
Hrs Hrs/ Occur 's
Yrs per Yr.
390 MW Thru 599 MW
1
2
3
4
5
6
7
8
9
10
600 +
1
2
3
4
5
6
7
8
9
4
6
7
6
9
9
9
8
6
3
MW
15
15
13
11
9
7
5
3
1
93.2
91.4
93.0
93.3
89.7
89.0
91.4
88.1
92.0
97.0
87.2
87.8
93.3
91.5
92.8
85.5
98.0
99.6
77.7
2697.2
5845.3
6134.4
13146.0
11269.7
9861.0
19716.0
6377.5
10512.0
26280.0
1603.6
1752.9
2279.0
4017.0
4930.5
4718.8
3981.81
6570.0
2190.0
319.5
39.2
245.4
69.5
53.5
45.2
138.0
557.8
18.2
0
193.6
384.5
92.8
155.4
213.6
97.8
69.2
24.3
345.3
3
1
1
1
1
1
0
1
1
0
5
5
4
2
2
2
2
1
3
MTTRFFO 5 Figure 6
Hrs of Merit
Term I
107
39
245
70
54
45
--
558
18
--
39
77
23
78
107
49
35
24
115
.859
.974
.912
.977
.979
.981
.964
.904
.998
.973
.908
.828
.977
.920
.920
.956
.968
.991
.823
'Reported by EEI for special request.
2MTBFFO-M.ean time between full forced outage.
3FOH-Forced outage hours per year.
"No. Fo-Number of ofrced outage occurrences per year.
5MTTRFFO-Mean time to repair a full forced outage - No. FO Occur
6Terms in computation of figure merit from Section
4.0 of this report.
FOB
43
-------
TABLE 5-9. OPERATING STATISTICS FOR GAS TURBINES
EEI
reporting
period
1960-1972
1964-1973
1965-1974
Units
In
432
346
565
Oper.
avail.
Ot>
90.6
90.8
89.0
MTBFFO1
(hn.)
784
765
807
RMA2
(I)
97.7
97.5
97.6
Ho.
MlltS
reporting
RMA
138
140
139
FOB*
(hrs/yc)
406
371
503
Ho.
occurrencea
per yr
10
10
10
MTTRFFO*
-------
100
Oi
90
S ao
5
70
YEARS IN SERVICE
A ~ '• UNITS
O — * UNITS
D - e UNITS
Figure 5-1. Availability of gas turbines vs. years in service.
-------
5.3.2 Replicate Unit Data
Data were obtained from the open literature which seem to show the trend
of unit performance as a function of the "learning curve" for a series of
essentially similar central station generating units. These power stations
contain the same type of equipment, designed and constructed by one
architectural/engineering firm. As the design of the generating station was
repeated from the construction of Big Sandy 2 through Gavin 2, the forced
outage rate for each of the units decreased significantly. Figure 5-2
shows forced outage rate as a function of plant life in months for these
stations and seems to illustrate validity of the "learning curve" hypothesis.
5.4 DATA TRENDS
The "learning curve" that has been hypothesized to apply to central
electrical generating stations, and appears to be supported by data as shown
in Figure 5-2, also is supported by data on individual pieces of equipment in
the generating system. The three phases shown in Figure 5-3 represent the
typical performance during the life of a piece of equipment. Phase I, the
early failure or "burn-in" phase, reflects the early troubles which often
arise with mechanical devices. During the second phase, which may be termed
the "useful life," the failure rate remains essentially constant or follows
a relatively slow change in value. Utility equipment components demonstrate
availability between 70 to 90 percent during their useful lives. Phase III,
the wear-out phase, illustrates the effects of aging when the equipment
begins to wear out. A comprehensive maintenance program can, however, delay
the occurrence of this phase.
In contrast to the data presented for power generating stations describ-
ing a "learing curve" and the apparent logic in the three phases of the
individual pieces of equipment, the data presented in this report consist of
composite totals and do not clearly show a "learning effect." As presented
in Figure S-4, fluctuation in Term I of the Figure of Merit for boilers and
turbines on a composite basis do not follow the failure rate diagram presented
46
-------
40
* 30
4-1
CO
•s
u
M
O
20 -
10 .
Amos 3
(1,300 MW)
Gavin
(1,300 MW)
Gavin 2 (1,300 MW)
Big Sandy 2
(800 MW;
0
4 6 8 10 12 14 16 18 20 22 24 26
Months from commerical operating date
Figure 5-2. Forced-outage rates for three 1,300-MW units plus 800-MW Big Sandy 2,
-------
t
oo
c
o
o
c
0)
4-1
Cfl
M
0)
Phase 1
early
failure
Phase 2
useful
life
Phase 3
wear
out
Time
Figure 5-3. Typical failure-rate characteristic for engineering devices.
-------
1.00-
VO
c
111
Ui *
of
XI 0»
IT »
1 S
U- «
c
UI
.7
.6-
.6-
.4
.3
.2
.1
O BOILER CONTROLLED CIRCULATION
E! BOILER ONCE-THRU SUBCRITICAL
A TURBINE TANDEM COMPOUND SUBCHITICAL
<3> TURBINE CROSS COMPOUND SUBCRITICAL
—r-
6
345
YEARS OF SERVICE
-T"
9
—1—
10
Figure 5-4. Equipment Maturity,
-------
in Figure 5-3. The data do not indicate a i .•» > ge variation in reliability
until the third year of operation. After the third year, the reliability of
each piece of equipment begins to vary significantly without indicating clear
trend which would support the failure rate diagram.
It should be emphasized that these composite data do not necessarily
contradict the failure rate diagram. It would seem valuable to obtain a
large amount of data on individual units in order to further test the hypoth-
esis. It could be that the failure rate diagram is blurred by the use of
composite data. Thus, although the data do not support the failure rate
diagram, they do not necessarily contradict it.
Data on the availability of the boiler in comparison with the avail-
ability of the entire unit has been plotted in Figures 5-5 and 5-6. These
plots do not seem to support the "learning curve" theory in that overall unit
availability is fairly constant over the first nine years of unit operation.
In addition, it is evident that the boiler is the equipment item which
predominately controls unit availability. Thus, new equipment, added to a
utility unit, must perform better than present boilers, if a degradation of
unit availability is to be avoided. Further, the turbine is the second least
available piece of equipment in a generating unit. Thus, new equipment added
in series with a generating unit, which performs as well as the turbine,
would not degrade the unit performance appreciably.
Finally, a very meaningful trend evidenced by the EEI data search was
the significant decrease in the number of units reporting RMA data. Over
50 percent of the units were reporting RMA data in 1971. The number of units
reporting RMA data has decreased to less than 10 percent of the operating
units from 1972 to the present. Thus, the most recent values of RMA may not
be representative. Although RMA is an optional reporting feature within the
EEI data system, it is the only reported statistic that measures, even second-
arily, the economics of repair/maintenance effort.
50
-------
Ul
l!
o?
zg
5s
K
Ul
a.
O
100 -
95 -
90
85
80
75
70
65
80
55
50
45
40
35
30
25
20
15
10
8
O BOILER ONCE-THRU SUBCRITICAL
A UNIT
—r-
8
—f
7
10
Figure 5-5.
345
YEARS OP SERVICE
Boiler and unit maturity 390-599 MW
-------
Ui
ho
o
h
If 4,
c
100
98 -
90
85
60
78
70
65
60
SB
50
40
35 -
30
25
20 -
16
10
5
H BOILER ONCE-THRU SUBCRITICAL
<•> UNIT
34567
YEARS OP SERVICE
10
Figure 5-6. Boiler and unit maturity 600 MW
-------
SECTION 6
FGD SYSTEM OPERATING DATA
Reliability data on operating FGD systems is scarce. At present the
only recognized data bank on FGD systems is the PEDCo Summary Report - Flue
Gas Desulfirrigation Systems (PE-227). The PEDCo report, which is prepared
under EPA contract, provides a continual update of the status and performance
of operational FGD systems. In addition, the report summarizes the status
of FGD systems in the construction or planning stage.
There are currently no efforts underway to gather the type of data
necessary to compare FGD system reliability to the reliability of other com-
ponents in the power generation train. Specifically, the type of information
which has traditionally been collected by EEI for boilers, turbines, conden-
sers, etc., has not been gathered for FGD systems. However, EEI's 1976
revised Equipment Availability Data Reporting Instructions (ED-060) have been
modified to include FGD systems.
6.1 DEFINITION OF TERMS
As discussed in Section A.O, data on FGD system operations is limited.
There are four parameters used by PEDCo in their bi-monthly FGD status reports
which are commonly used in reporting FGD system operating data. These four
parameters, as defined below, will be used in the following sections to report
the FGD system operating data collected during this study.
Hours the FGD system was available
,. . ., i. •• .,„ for operation
1) Availability = - 7^—r 7—:
' Hours in the period
53
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. _ Hours the FGD system was operated
i) Rel ab lity - Hours tlie system was required to operate
_N „ .... Hours the FGD system was operated
3) Operability Hours the boiler was operated
.. TT Hours the FGD system was operated
4) Utilization Hours in the period
6.2 SOURCES AND AVAILABILITY OF DATA
The major source of FGD system performance data presented in this report
is the PEDCo Summary Report - Flue Gas Desulfurization Systems (PE-227).
Unfortunately, this data is incomplete over the life of the six lime/limestone
FGD systems identified in Section 3.2.2. Table 6-1 summarizes the performance
data which is published in PEDCo's report. The table identifies which param-
eter is reported for each system and the time period for which the parameter
has been reported.
TABLE 6-1. DATA AVAILABLE FROM PEDCo's FGD SUMMARY REPORT
System Availability Reliability Operability Utilization
Cholla 1/74 - 8/76
Will County 3/75 - 7/76 3/75 - 7/76* 3/72 - 7/76 3/75 - 7/76
Phillips 7/75 - 3/76
LaCygne 1/75 - 8/76 1/74 - 12/74
Green River 12/75 - 8/76 12/75 - 8/76 12/75 - 8/76 12/75 - 8/76
Paddy's Run 4/73 - 8/76
*Reliability as calculated by PEDCo for Will County -
Hours FGD System Operated
Hours system operated + (Period hours - Available hours)
54
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It is evident from Table 6-1 that there is no common parameter reported
for all six systems. Operability is reported for four while availability,
reliability, and utilization are reported for three of the six systems.
The following utilities were contacted in an effort to expand the avail-
able data base and to collect data for FGD systems similar to that which is
reported by EEI for other utility components (e.g., mean time between fail-
ures, mean time to repair and relative mechanical availability). However,
it was discovered that the utilities which operate FGD systems do not collect
this type of data. This reflects the fact that no standardized procedure
currently exists for reporting FGD system reliability data. The utilities
that were contacted are as follows:
1) Arizona Public Service Company (APS)
2) Commonwealth Edison Company (CE)
3) Duquesne Light Company (DL)
4) Kansas City Power and Light Company (KCP&L)
5) Kentucky Utilities Company (KU)
6) Louisville Gas and Electric Company (LG&E)
As a result of the contact with KU, American Air Filter Company (AAF) was
contacted for information on the Green River FGD systems.
Several of the companies contacted asked for a written request for the
information and/or data forms to fill out. Data forms were prepared which,
if completed, would provide performance data on the FGD systems from start-
up through the present (Figures 6-1 through 6-3). In addition, the completed
forms would permit calculation of parameters such as mean time between fail-
ures, mean time to repair, and relative mechanical availability.
Only Commonwealth Edison and American Air Filter provided additional
FGD performance data for this evaluation. Commonwealth Edison provided
Radian with Monthly Progress Reports and Running Times and Outages for
55
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TCP SYSTEM RELIABILITY INFORMATION
System
Start-Up Dace
Nuaber of Modules
Size Of Modules (ACFM)
Total System Operating Hours
Total Boiler Hours in Period for Which tecs Is Available
Toc«l Hours System Was Required to Operate
Total Hours System Has Available Co Operate
Longest Continuous System Operation
Average Load on System per Operating Hour
Maintenance Hours per Module per Week
Figure 6-1. Data form 1.
FCC STTSTW ULXAtlUTT
Mooch/
Y««r
Hourl loiltr
Op
Inquired to Of*nt»
Houn Modul* U«<
Available Co Oparaee
Figure 6-2. Data form 2.
56
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FOB SYSTEM MLIABJLITT INFORMATION
Description of F«ilur«
l/l
Percent
1 At
T/.11..M
Figure 6-3. Data form 3.
-------
the Will County FGD System. These documents covered the time period from
February 1972 through September 1976. American Air Filter provided avail-
ability, reliability, and operability data for the Green River FGD System
for the period through September 1976. In addition, utilization data was
provided for September 1975 through December 1976.
One additional source of performance data was a report prepared by
Radian Corporation for the EPA. This report, entitled Review and Analysis of
Louisville Gas and Electric Scrubbing System Data, contained nine months of
utilization data for LG&E's Paddy's Run System.
Table 6-2 summarizes the performance data collected by Radian. These
data do not provide any parameters in addition to those reported by PEDCo.
However, the data do provide FGD performance information over a longer time
period.
TABLE 6-2. DATA COLLECTED BY RADIAN
System
Availability
Parameter
Reliability
Operability
Utilization
Choila
Will County
Phillips
LaCygne
Green River
Paddy's Run
2/72 - 8/76
12/75 - 9/76
2/72 - 8/76 2/72 - 8/76
12/75 - 9/76 12/75 - 9/76 9/75 - 9/76
4/73 - 12/73
Although the data collected results in a more complete performance his-
tory, the information is not comprehensive. Table 6-3 depicts the start-up
data for each system and the date from which performance data is reported.
For Will County, Green River and Paddy's Run, at least one parameter has been
58
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collected from the date of start-up. However, performance data for the other
three systems did not begin until some point in time subsequent to the start-
up date.
TABLE 6-3. PERFORMANCE DATA COLLECTION VS SYSTEM OPERATION
Date Data Collection
System Start-up Date Began
Cholla 9/73 1/74
Will County 2/72 2/72
Phillips 8/73 7/75
LaCygne 6/73 1/74
Green River 9/75 9/75
Paddy's Run 4/73 4/73
The preceding discussion and table emphasize the requirement for an
organized and standardized system for reporting FGD system reliability data.
Section 8.0 contains recommendations for collecting the data required to
determine FGD system reliability in comparison to utility component
reliability.
6.3 DATA PRESENTATION
Data which report the performance of operating FGD systems is limited
to the four parameters defined in Section 6.1. Table 6-4 illustrates average
values for the performance data which have been reported for the FGD systems
under consideration in this study. In addition, the time period covered by
the reported data is shown. The supporting information which was used to
calculate the averages presented in Table 6-4 can be found in Appendix C.
59
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TABLE 6-4. FGD SYSTEM PERFORMANCE DATA - AVERAGE VALUES
Availability Reliability Durability Otllliatlon
Cholla - Nodule A
Will County - Module A
Will County - Module B
Phillip* - All Nodule*
LaCygne ~ A11 Nodulee
Green River
Paddy's lun - AH Nodule*
92.21 (30 month*)
*3.0X (53 month*) 40.01 (S3 month*) 33.61 (53 month*)
43.71 (31 Month*)* 21.01 (55 aonth*) 16.41 (55 month*)
*** 61.3% (9 months)
88. IS (17 •rath*) 76.31 (10 month*)"
82.6: (10 month*) 84. 3X (10 month*) 80.81 (10 month*) Sl.OS (13 month*)
41.81 (42 months) 28.3X (9 monthi)
Thla value for availability do** not Include the 24 month period from 5/73 to 4/75 during which
the *y*t«* did not operate. (See Figure C-4 in Appendix C.)
* Thl* value for oparablllty 1* bated on mil seven scrubber module*.
Therefore vhen fever than aeven are in aarvlce, operablllty 1* le*a
than 100 percent.
••• Operatlm« mat* provide* after thl* report *m* laaued.
-------
As illustrated in Table 6-4, the average values of the performance
parameters vary from one system to the next. The relationship between these
average values and the value of each of the performance parameters applied
to FGD systems as a class is not immediately evident. One method of inter-
preting the data in Table 6-4 is to apply statistical analysis and calculate
a range in which the "true" value of an individual performance parameter
lies.
Table 6-5 presents a range for each of the performance parameters.
These ranges were determined on the basis of the average values in Table 6-4.
According to simple probability theory, the "true" value of each of the four
performance parameters should lie in the given ranges.
TABLE 6-5. RANGES FOR PERFORMANCE PARAMETERS
Parameter
Range
Confidence Level
Availability
30.2 £ A £ 100
0 < A < 100
90%
99%
Reliability
63.2 £ R £ 100
0 < R < 100
90%
99%
Operability
0 £ 0 < 99
0 < 0 < 100
90%
99%
Utilization
27.6 £ U £ 69.2
3.5 < U < 93.3
90%
99%
The following sample calculation details how the ranges presented in
Table 6-5 were determined.
61
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Availability - A
Will County = 43.35% Average Availabilities
LaCygne = 88.1 % Average Availabilities
Green River = 82.6 % Average Availabilites
Assuming measured FGD system availability is arrayed in a normal distri-
bution about the "true" value of availability for FGD systems as a class,
the following relationships apply (GR-255).
(u-t --) < u < < + t --) (6-2)
~ ~~
where
a2 = The square of the standard deviation of a population
estimated by the Bessel correction.
n = Number of samples taken, which in this application
represents the number of systems that have reported
data.
x, = Individual value of each sample or the value of the
performance parameter reported for a single system.
u « Estimate of the true value of a performance parameter
which is the average of x *s.
u = The "true" value of a performance parameter.
62
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t = Variate of the Student's "t" distribution which is
determined by the number of samples and the confi-
dence level assigned to the range.
To calculate a range in which the true value of availability lies,
set A = u and place a 90% confidence level on the range. Then,
A 43.35 + 88.1 + 82.6 _, ,_
Average = u = - - - = 71 . 35
a2 -
[(43.35 - 71.35)2 + (88.1 - 71.35)2 + (82.6 - 71.35)2]
A2 784 + 280.6 + 126.6
a = ^
a2 = 595.6 a - 24.4
From the Student's "t" test, "t" =2.92
when n-1 = 2 and P = 95 (Probability value equivalent
to a 90% confidence level).
71.35 . (2.92)(24.4A < A < /n.35 + (2.92)<24.4)
r "v ^
with 90% confidence
or
30.2 £ A £ 100
The preceding calculation is based on a normal distribution of perfor-
mance parameters about a true value. Although this assumption may not repre-
sent the actual distribution of FGD system performance parameters, it is
valid due to the small number of data points that currently exist.
63
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Table 6-5 illustrates the fact that the performance data which is
currently available is insufficient to permit a "true" determination of FGD
system performance. The narrowest range is for utilization (20 percent) and
if the confidence level is increased to 99 percent, all but the utilization
parameter range expands to cover all possible values of the performance
parameters (i.e., 0 < parameter < 100).
6.4 DATA TRENDS
Based on the above discussion, it is evident that FGD system performance
data is not statistically significant. However, actual performance data does
permit some interesting observations. For example, Figures* 6-4 and 6-5
depict availability data for Will County - Module A and the Green River
System. The Will County System, which is the oldest of the six, has an aver-
age availability of 43.0 percent. This average represents rather erratic
system performance and includes ten 1-month periods in which the system
was not available at all. Green River, on the other hand, is the newest of
the six systems. This system has an average availability of 82.6 percent
which represents relatively stable system operation for the first year of
operation.
These facts seem to suggest that the design and operation of FGD systems
has benefited from experience gained over the past several years. This is a
common stage in the development of most mechanical and chemical systems.
Another FGD system which has a high availability yet is relatively old
is the LaCygne installation. Figure 6-6 illustrates the average reliability
for the LaCygne scrubber. This average represents relatively stable system
operation and no major failures (massive scaling, etc.). However, and impor-
tant factor which the availability parameters masks is the maintenance man-
hours expended in servicing the system.
*A complete set of graphs for other performance data is presented in
Appendix C.
64
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Ul
2* 30 38
TIME FAOM START-UP (MONTHS!
46 50
Figure 6-4. Will County FGD system availability - Module A.
-------
t
>•
AVERAGE AVAILABILITY . >2.«%
<* 10
>* 30 it
TIME FROM START-UP IMOHTHM
40 «S
—1
so
Figure 6-5. Green River FGD system availability.
-------
AVERAGE AVAILABILITY . SS.t*
so
10 It
to is *•
TIMC FROM •TANT-UP IMOHTHSI
40 4S SO SS
Figure 6-6. LaCygne FGD system availability - average all modules.
-------
Current operating practice at the LaCygne scrubber is to shut one module
down each night and have a maintenance crew clean and inspect the scrubber.
The high system availability is in part attributable to the massive main-
tenance effort at LaCygne. The scrubber operating and maintenance force
currently totals 51 people. Although the LaCygne system is a unique case,
it does indicate that a scrubber can be operated reliably with sufficient
expenditure of cost and effort.
Another interesting surmise can be made by observing Figure 6-7 which
depicts reliability for Cholla - Module A. The Cholla system has a high
average reliability (92.2 percent) along with several features which make
Cholla unique among FGD systems. First, this system scrubs about 12 Ibs
SOz per ton of coal burned. This compares to other systems which scrub 72
to 180 Ibs SOz per ton of coal burned. In addition, the Cholla system
operates open loop with no water being recycled to the FGD system from the
disposal pond.
The high average reliability of the Cholla FGD system can be attested
to the above factors which serve to virtually eliminate the chemical scaling
and plugging problems that have plagued many of the other FGD systems. The
success of this unit seems to indicate that control of the process chemistry
is of foremost importance in improving the reliability/availability of FGD
systems.
68
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AVERAGE BEllABItlTK . »2 2»
V£>
It 30
TIME FHOM STAHT-UP IUONTHM
40 4*
Figure 6-7. Cholla FGD system reliability - Module A.
-------
SECTION 7
RESULTS
The results of this study indicate that several important operating
parameters must be reported before a meaningful comparison of FGD systems and
utility components can be made. In particular, for utility equipment:
1) Data to compute RMA should be reported to EEI
on a mandatory basis.
2) The learning curve data in the EEI and FPC data banks
should be examined and analyzed. This requires data
reporting by unit and by age of unit.
The following information should be gathered for both existing and new FGD
sys terns:
1) Data to compute RMA, mean time between failure, and
mean time to repair should be reported to EEI as
these data become available.
2) Mean time between full forced outages (MTBFFO) and
mean time to repair full forced outages (MTTRFFO)
should be reported to EEI.
Utilities are not required to submit data on RMA to EEI. Upon examining
the EEI special data search, it was discovered that only a few utilities are
currently reporting values for RMA. As a result, the RMA values reported by
70
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EEI may not represent current practice. A concerted effort to gather the
data necessary to complete RMA is required from a large number of utilities.
Learning curve data can be derived from a combination of the EEI data
base and the Federal Power Commission (FPC) annual data reports required from
each utility. The EEI data must, however, be available on a unit by unit
basis to complete the combination. The current EEI procedures prohibit the
dissemination of unit operating performance without the consent of the
utility involved. This policy is under review by the Prime Movers Committee
and may be revised.
The results of the search for FGD system performance data made it clear
that current reporting procedures are both incomplete and inconsistent. All
of the data required to calculate the Figure of Merit must be reported for
FGD systems. Values for MTBFFO, MTTMTO, RMA, and •£ (learning curve data)
are not currently reported in any organized fashion. Certainly this is the
major task which remains to be completed before any meaningful comparison
can be made.
An important result of this study was the identification of the time-
frame during which new FGD systems will be coming on line. Table 7-1 illus-
trates the estimated number of full scale (larger than 50 MW) lime/limestone
systems which will have operated for at least one year in the years ending
1977 through 1980. Table 7-1 also projects confidence limits for predicting
the availability of these systems during the same time span. An important
assumption used to project these confidence limits is that data will be
collected at all operating FGD systems as they come on line.
At this time, it is difficult to state with certainty exactly when a
meaningful comparison of FGD systems and utility components can be made.
Certainly, no comparison should be attempted before the performance of FGD
71
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10
TABLE 7-1. PROJECTED CONFIDENCE LIMITS FOR AVAILABILITY
PARAMETER - LIME/LIMESTONE SYSTEMS
Month/Year
12/77
12/78
12/79
12/80
Total Number of Lime /Limes tone
Systems with 1 Year of Operation15
16 (5,300 Mtf)
31 (13,000 MW)
41 (16,900 MW)
53 (22,700 MW)
Confidence Limit for
Availability Parameter"
± 10.7%
i 7.4%
± 6.4%
i 5.61
Confidence
Level
901
907.
90%
90%
a These confidence limits assume that availability is arrayed in a normal distribution
about the average. In addition, it is assumed the standard deviation calculated in
Section 6.3 is constant.
b These numbers are excerpted from PEDCo's FGD Summary Report (PE-227). The values for
1979 and 1980 are probably low due to the number of FGD systems which have not been
•elected.
-------
systems can be estimated to + 10.0 percent accuracy with 90 percent rnnfi-
dence. Table 7-1 indicates that at the earliest, this will be possible
when data through the end of 1978 is available. This is, of course, contin-
gent on acquiring accurate and meaningful data from both operational and new
FGD systems.
73
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SECTION 8
CONCLUSIONS AND RECOMMENDATIONS
Utility and FGD system performance data were collected and analyzed, and
a comparison model was developed in an effort to compare the reliability/
availability of FGD systems and utility equipment. The following conclusions
and recommendations are presented to highlight the results of this study.
8.1 CONCLUSIONS
1) A statistically meaningful comparison of the reliability/
availability of utility and FGD systems cannot now be made,
primarily because of the small amount of FGD system perfor-
mance data currently available. A meaningful comparison
can be made after more FGD systems are installed and more
complete performance records become available. Calcula-
tions show that FGD performance can be estimated to within
10 percent with a 90 percent confidence level when 1978
data becomes available if all FGD systems that are expec-
ted to come on line will report the necessary data.
2) The comparison model of Figure of Merit provides a better
basis of comparing or ranking dissimilar pieces of equip-
ment or systems than any single parameter currently being
recorded. A meaningful comparison basis should include
several parameters which effect the overall performance of
a system or system component such as: 1) a measure of the
maintenance/economic requirements, 2) a scale-up or learning
74
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function, and 3) mechanical availability. The Figure
of Merit developed in this study considers these factors
which directly influence the performance of a piece of
equipment to provide a valid basis for comparing dis-
similar pieces of equipment or systems.
3) The product of Term I and Term II in the Figure of Merit
exceeds 50 for all equipment installed by the utility
industry. The boiler appears to be the equipment item
within the utility industry which controls the unit per-
formance. FGD systems will certainly have to demonstrate
a performance such that the product of Term I and Term II
is greater than 50 to demonstrate a performance character-
istic which is comparable to the present components used
in the utility industry.
8.2 RECOMMENDATIONS
1) The collection of complete performance data for both FGD
and utility systems should be implemented on a regular
basis. In particular, the terms identified in Section 4.2
of this report should be recorded. These are: mean time
between full forced outage, mean time to repair a full
forced outage, relative mechanical availability, and the
number of replications of a piece of equipment or plant.
The cooperation of the utility industry should be enlisted
in preparing a report similar to the Summary Report - Flue
Gas Desulfurization Systems (PE-227) currently prepared by
EPA. The set of parameters listed above should be reported
for each FGD system so that meaningful comparisons can be
made. This reporting procedure should include each new FGD
system as it comes on line.
75
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2) Any additional data collection efforts should be
coordinated with either the ANSI steering committee
on data availability or EEI in order to avoid bur-
dening the utility industry with redundant data col-
lection requests. Only one computer-based data
collection system is required to accumulate and
report the data on utility and FGD system. FEA,
NARDC, NCR, EPRI, ANSI, FPC, CEQ, EEI, and EPA
should identify their individual data requirements,
then present one coordinated approach to the utility
industry for obtaining the needed data.
3) Data concerning the "learning curve" or "number of
replications" were not forthcoming from the search
of the EEI data bank performed for this study. It
is recommended that a special search to obtain this
data from EEI be sponsored thru EEI.
76
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BIBLIOGRAPHY
BA-185 Babcock & Wilcox, Steam/Its Generation and Use. 38th edition.
New York, 1972.
FR-P- Fryling, Glenn R., ed., Combustion Engineering, revised edition.
287 New York, Combustion Engineering, Inc., 1966.
ED-043 Edison Electric Institute, Prime Movers Committee, Equipment
Availability Task Force, Report on equipment availability for
the ten-year period. 1965-1975.. EEI Pub. No. 75-50, N.Y.,
November 1975.
ED-057
ED-058
ED-060
EN-211
GR-255
PE-030
PE-227
Edison Electric Institute, Prime Movers Committee, Equipment
Availability Task Force, Report on equipment availability for
availability for the ten-year period. 1964-1973., EEI Pub. No.
74-57., N.Y., December 1974.
Edison Electric Institute, Prime Movers Committee, Equipment
Availability Task Force, Report on equipment availability for
the thirteen-year period, 1960-1972., EEI Pub. No. 73-46,
N.Y., December 1973.
Edison Electric Institute, Prime Movers Committee, Equipment
Availability Task Force, Equipment availability data reporting
instructions, N.Y., January 1976.
Environmental Protection Agency, National Public hearings on
power plants compliance with sulfur oxide air pollution
regulations. Hearings conducted 18 October 1973 through
2 November 1973, January 1974.
Green, A. E. and A. J. Bourne, Reliability Technology.
N.Y., Wiley-Interscience, 1972.
Perry, John H., Chemical Engineers Handbook. 4th ed. New York
McGraw-Hill, 1963. '
PEDCo Environmental Specialists, Inc., Summary report - flue gas
desulfurization systems. July-August 1976. EPA Contract No
68-02-1321, Task No. 28, Cincinnati, Ohio, 1976.
77
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TI-038 Tillinghast, John and John E. Dolan, "AEP successeds with large
new units," Elec. World 186 (3), 28 (1976).
US-391 U.S. Atomic Energy Commission, Reactor safety study. An Assess-
ment of accident risks in U.S. commercial power plants, final
report, 9 vols., WASH-1400, NUREG-75/014. Summary and main
reports, appendices 1-11., October 1975.
78
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APPENDIX A
MODEL DEVELOPMENT
79
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MODEL DEVELOPMENT
REQUIREMENTS FOR THE COMPARISON
The comparison technique should contain the following elements:
A) Existing data should be applicable to the comparison
technique.
B) New data, if required, should not be too difficult to
obtain.
C) The comparison technique should be relatively simple
to compute and apply.
D) The comparison technique should include at least the
following:
1) "Mechanical" availability,
2) Maintenance/economic measure, and
3) Scale up or learning function.
MECHANICAL RELIABILITY
If a component within the utility unit or the unit itself is in the
random failure state, then the reliability of the component or unit can be
expressed as
R(t) - e'Xt ,
80
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t = time of operation, and
X = failure rate (occurrences per unit time).
Now define a similar term for the repair of a component or unit, again
where repair is in the random repair state, such that
M(T) = e^ ,
4> = repair rate (occurrences per unit time), and
T = time of repair.
Thus, M(T) is the probability that a repair will still be in progress after
time, T. Conversely, the probability that a repair will be complete within
time T is
Now, take into account that satisfactory repair of the component is possible
within the time constraint, T, and that the component (or unit) would then
be operational. The component may fail a second or third time, and on the
occasion of each, a repair would be attempted. Based on the Poisson distri-
bution, the probability a component will be operational at the end of time,
t:
without a failure = e
with one failure = Xte
with two failures =
,, ,1 -Xt
with i failures = U ; *
-L. •
81
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Now, following every failure, a repair is attempted. The probability
that the repair will be completed in time, T, is (1-e ? ). The probability
of a component with one failure being repaired within T and being operational
at the end of time t, is
i -/i
Ate (1-e
Similarly, with i failures, the probability of each failure being repaired
in time, T, and the unit being operational at the end of time, t, is
The probability of repairing all failures within the time, T, and being
operational at the end of time, t, is
V at)1
i!
i-0
e"Xt ^ at>ia-.-*t)i
This equation defines reliability such that if a unit or component is
repaired within a time, T, and is operational at the end of time, t, the
unit or component has successfully performed its task.
82
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Discussion
In practice the failure rate, X, is the reciprocal of the mean time
between failures. The repair rate, <(>, is the reciprocal of the mean time
to repair. Both of these terms apply only in the random failure or repair
modes when the rates are constant with respect to time and do not include
early or premature failure modes or wear out failure modes.
This approach toward reliability then gives almost equal credit to the
component which has 1) an extremely long time between failures and associated
long time to repair, and 2) frequent failures and short repair times. An
analogy might be that 1) is an extremely thoroughly designed and quality-
built component versus 2) which is produced without benefit of all of the
effort associated with (1). This represents the trade-off between initial
capital investment and continuing maintenance expense. Equation [1] addres-
ses requirement itemD(l).
RELATIVE MECHANICAL AVAILABILITY (RMA), A MEASURE OF EFFORT
"Relative Mechanical Availability is a form of Operating Availability
adjusted to show relative effort. The prime assumption is that most outage
time is affected by work schedules and crew sizes. Relative Mechanical
Availability uses an Adjusted Outage Time (AOT) based on effort. Manhours
worked is a measure of effort which is reasonably independent of work
schedules and crew sizes. Manhours worked (MH) divided by a standard work
force (SWF) gives a derived time worked based on effort. If we assume a
round-the-clock schedule, then this derived time worked is almost a derived
outage time based on effort. The difference is the amount of outage time
which is independent of effort called Hours Waiting (HW)."1
lfThe quotations are from £EI publication 75-50, "Report on Equip-
ment Availability for the Ten-Year Period 1965-1974, (ED-058).
83
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Hours waiting is "that portion of time for any outage during which no
work could be performed. This includes time for cooling down equipment
and shipment of parts. This is time that could not be affected by a change
in work schedule or the number of men worked."
An arbitrary assumption of ten men for the standard work force gives:
AOT = HW + MH/10
Then, substituting AOT for outage time in the equation for operating avail-
ability gives:
RMA - [(PH-AOT)/PH] 100
[(PH-(HW + MH/IO))/PH] 100
Where
PH, the Period Hours* is "the clock hours in the period under consider-
ation. (Generally one year)."
Discussion
RMA is a factor which directly considers the repair effort required to
return equipment to an "available" status. It is possible that RMA could be
negative if the manhours for repair are ten times greater than the total
period hours (excluding waiting time considerations). This would indicate
an extremely labor intensive component. RMA then is a maintenance/economic
measure as stated in requirement D(2).
THE LEARNING FUNCTION
The learning function is a measure of increased performance based on
repetition. In design and manufacturing, the learning function can be
84
-------
handled as decreasing alloted time for a given function or as a single time
allotment with a decreasing learning factor. Each of these approaches is
applied to a measurable function and tends to decrease the alloted time for
a given function as the number of repetitions is increased. This function
nominally takes the form shown in Figure A-l.
I
•H
H
u
n)
•0
Number of Repetitions
Figure A-l. Learning curve showing decrease of standard
time with increase of repetitions.
The analogy in central station design, construction and operation is
increased performance with decreased cost as a function of the number of
repetitions completed. In this case, the time span to complete a learning
cycle is much longer than ever encountered in manufacturing operations.
For purposes of this comparison model, the learning function is a simple
fraction raised to an exponent. This form is suggested by the similarity
between the classical learning function curve (MA-875) and the "six-tenths"
factor curve (PE-030). The six-tenths factor applied to the learning func-
tion has values as shown in Table A-l.
85
-------
TABLE A-l. VALUES OF THE LEARNING FUNCTION
i
1
2
3
4
5
f i xO.6
4+l.CT
.66
.78
.84
.87
.90
, i ,-0.6
^i+1.0;
1.52
1.27
1.19
1.14
1.11
Based on this learning function, a potential 25 percent increase in the
Figure of Merit can be achieved after five repetitions. The learning func-
tion in the Figure of Merit computation is applied in an inverse manner.
The Figure of Merit for the first of a kind component can be compared with a
component which has had the benefit of repetition on essentially an equal
basis. The learning function addresses requirement D(3).
References
MA-P-875 Maynard, H.B., ed., Industrial Engineering Handbook. Second
Edition. New York, McGraw-Hill, 1963.
PE-030 Perry, John H., Chemical Engineering Handbook. Fourth Edition.
New York, McGraw-Hill, 1963.
86
-------
APPENDIX B
UTILITY COMPONENT DATA
87
-------
The data presented in Appendix B were obtained from operating utilities
for several different types and sizes of boilers and turbines. Each data
point on a figure represents the average availability for one component year
of service, starting at year zero when the component was declared commer-
cially available. The heavy line in each figure connects the average avail-
ability for all components during the year of service.
Note: The definition of availability for all figures in Appendix B is
the hours a unit is synchronized to the bus divided by the period hours.
This definition yields availabilities lower than would be computed using the
EEI definition. The difference is in the time necessary to bring a unit up
to synchronic speed and bus connection. This can amount to as much as 36
hours difference per start for large units.
88
-------
oo
10
100
90
80 .
70 .
60-
1234
5 6 7 8 9 10
Years in Commercial Service
Figure B-l. Super critical, once thru boilers availability vs. years in service,
-------
vo
O
I
100 -i
90 '
80
70
50
. I
1 2
6 8 10
Years in Commercial Service
12 14
Figure B-2. Boiler, larger than 500 MW availability vs. years in service.
-------
100
90
80
I
\o
60 .
J 2
6 8 10
Yearn In Commercial Service
12 14
16
Figure B-3. Boiler, 300 MW availability vs. years in service.
-------
to
ro
100
90
£•80
3
I
70
60
40 .
B 10 12
Yearn In Comerclal Service
16
18
—r—
20
Figure B-4. Boiler, 200 MW size availability vs. years in service.
-------
100
90
^ «o
VO
U)
70
60
I 2
10 12 14 16
Ye.irs In Coramnrci.il Service
18 20
22
Figure B-5. Boiler, 175 MW size availability vs. years in service.
-------
100
\D
tf
80
70
50
40
fl 10 12
Yeors In Cnmncrcl.il Service
16
18
22
Figure B-6. Boiler, 125-150 Mtf size availability vs. years in service.
-------
vo
11)0 -\
80
70 .
T
T1
10
6 a
Years in Commercial Service
Figure B-7. Steam turbine, >500 MW size, super critical availability
vs. years in service.
-------
VO
100 -
90 •
« 80
•rl
rH
•H
JO
a 70
60
50
(, 8 10 12
Years In Commercial Service
16
Figure B-8. Steam turbine, 300-500 MW size, availability
vs. years In service.
-------
VC
inn
I 2
8 10 12 1
Years in Commercial Service
16
'.0.2
18
20
Figure B-9. Steam turbine, 200 MW size availability vs. years in service,
-------
00
100
90
. 80
3 70
60
50
I t
10 12 I/, If,
Vf;ns in f'unmie rr I a I Service
18
20
22
Figure B-10. Steam turbine, 175 MW size availability vs. years in service.
-------
V0
NO
100
90
80
3 70
-0
ni
60
10 12 14 16
Years In tonmerclal Service
20 22
Figure B-ll. Steam turbine, 125-150 MW size availability vs. years in service.
-------
O
O
100
90
£• 80
70 .
60
3 4
Years In Commercial Service
Figure B-12. Gas turbine, 20-25 MW size availability vs. years in service.
-------
100
90
80
70
ftO
I
2 3
Years In Commercial Service
Figure B-13. Gas turbine, 59-70 MW size availability vs. years in service.
-------
JOO •
98
96 -
9/4
92
90
88
86
84
B2
80
Years in Cfiirawrrlal Service
Figure B-14. Electrostatic precipitators availability ye. years in service.
-------
APPENDIX C
FGD SYSTEM DATA
103
-------
The information presented in Appendix C is divided into three basic
areas:
1) FGD System Reliability Information
2) Graphical Representations of FGD System Performance
3) Calculations
The data presented in the first section are the monthly performance
statistics for the following FGD systems.
1) Arizona Public Service Company's Cholla Generating
Station - Unit No. 1.
2) Commonwealth Edison Company's Will County Station -
Unit No. 1.
3) Duquesne Light Company's Phillips Station.
4) Kansas City Power and Light Company's LaCygne Station.
5) Kentucky Utilities Company's Green River Station.
6) Louisville Gas and Electric Company's Paddy's Run
Station - Unit No. 6.
Host of the data presented are on an hours per month basis. However, in
some instances this information was not forthcoming and the values for cer-
tain performance parameters are expressed on a percentage basis.
The data in this first section are limited to the "FGD Reliability
Information" Forms 1 and 2. Radian was not able to complete Form 3 for any
system and Forms 1 and 2 have only been partially completed.
104
-------
The second section of this Appendix contains a series of figures. These
figures are a graphical representation of the data presented in Form 2. The
figures represent month by month performance of the FGD system. The average
value of the system performance is also illustrated in these figures.
The final section of this Appendix contains detailed calculations which
were used to determine the ranges for the four FGD system performance param-
eters. These ranges are presented in Table 6-5 in the body of the report.
105
-------
FGD SYSTEM RELIABILITY INFORMATION
FORMS 1 AND 3
106
-------
Form #1
FGD SYSTEM RELIABILITY INFORMATION
System Cholla
Start-Up Date 10/73
Number of Modules 2
Size of Modules (ACFM) 260»000
Total System Operating Hours
Total Boiler Hours in Period for which Data is Available
Total Hours System was Required to Operate
Total Hours System was Available to Operate
Longest Continuous System Operation
Average Load on System per Operating Hour _________
Maintenance Hours per Module per Week
107
-------
Fora f 3
o
oo
FGD SYSTEM RELIABILITY INFORMATION
SYSTEM Cholln MODULE A
Month/
Year
1/74
2/74
3/74
^ ITt
5/74
6/74
7/74
8/74
9/74
10/74
11/74
12/74
Hours Boiler
Operated
Generation
Capacity (I)
Hours Module
Operated
Reliability (I)
97
100
100
66
98
100
97
97
95
83
100
100
Hours Module Was
Available to Operate
-------
Form f3
o
lO
FGD SYSTEM RELIABILITY INFORMATION
SYSTEM chr.1 1 a MODULE A
MonLh/
Year
1/75
2/75
3/75
4/75
5/75
6/75
7/75
8/75
9/75
10/75
11/75
12/75
Hours boiler
Operated
Generation
Capacity (I)
Hours Module
Operated
Reliability (%)
98
96
88
48
100
97
95
98
84
100
100
Hours Module Was
Available to Operate
-------
Form |3
FGD SYSTEM RELIABILITY INFORMATION
SYSTEM Phnl 1 a MODULE A
Month/
Year
1/76
2/76
3/76
4/76
5/76
6/76
7/76
8/76
Hours Boiler
Operated
Generation
Capacity (I)
Hours Module
Operated
Reliability (1)
99
99
76
64
100
100
Hours Module Was
Available to Operate
-------
Fora *3
FGD SYSTEM RELIABILITY INFORMATION
SYSTEM rhnl1a MODULE R
Month/
Year
1/74
2/74
3/74
4/74
5/74
6/74
7/74
8/74
9/74
10/74
11/74
12/74
Hours Boiler
Operated
Generation
Capacity (%)
Hours Module
Operated
Reliability (t)
90
94
66
57
99
100
92
97
99
68
98
100
Hours Module Was
Available to Operate
-------
Form |3
FGD SYSTEM RELIABILITY INFORMATION
SYSTEM rK-o-i. MODULE »
Month/
Year
1/75
2/75
3/75
4/75
5/75
6/75
7/75
8/75
9/75
10/75
11/75
12/75
Hours Boiler
Operated
Generation
Capacity (X)
Hours Module
Operated
Reliability (I)
99
99
65
40
100
98
100
97
55
80
100
Hours Module Was
Available to Operate
10
-------
Form |3
FGD SYSTEM RELIABILITY INFORMATION
SYSTEM Choila MODULE B
Month/
Year
1/76
2/76
3/76
4/76
5/76
6/76
7/76
8/76
.
Hours Boiler
Operated
Generation
Capacity (I)
Hours Module
Operated
Reliability (%)
99
98
100
39
98
100
Hours Module Was
Available to Operate
-------
FGD SYSTEM RELIABILITY INFORMATION
Form #1
System
Start-Up Date
Number of Modules
Size of Modules (ACFM)
Total System Operating Hours
Total Boiler Hours in Period for which Data is Available
Total Hours System was Required to Operate
Total Hours System was Available to Operate
Longest Continuous System Operation
Average Load on System per Operating Hour
Maintenance Hours per Module per Week
Will County
2/72
385,000
A=12681 B=6458
29234
A=17754 B=9435
114
-------
Form fll
FGU SYSTEM RELIABILITY INFORMATION
SYSTEM Will County MODULE A
H
M
Oi
Month/
Year
1/72
2/72
3/72
4/72
5/72
6/72
7/72
8/72
9/72
10/72
11/72
12/72
Hours Boiler
Operated
628
640
525
649
649
690
46
0
226
719
Generation
Capacity (71)
Not Available
Hours Module
Operated
0
0
0
218
365
55
179
476
0
0
0
150
Hours Module Was
Required to Operate
Hours Module Was
Available to Operate
0
333
667
55
179
476
720
744
720
253
-------
l-'orin f 3
FGD SYSTEM RELIABILITY INFORMATION
SYSTEM mil rn,.nt-« MODULE
Month/
Year
I/™
2/73
3/73
A/73
5/73
6/73
7/73
8/73
9/73
10/73
11/73
12/73
Hours Boiler
Operated
568
672
636
614
735
512
677
668
553
738
633
627
Generation
Capacity (Z)
Not Available
Hours Module
Operated
48
161
413
0
0
107
324
110
6
355
201
0
Hours Module Was
Required to Operate
Hours Module Was
Available to Operate
48
161
413
0
0
720
360
110
6
355
201
0
-------
Kotm |'J
FGD SYSTEM RELIABILITY INFORMATION
SYSTEM Hill Couqcy MODULE A
Moiil.li/
Year
1/74
2/74
3/74
4//4
5/74
6/74
7/74
8/74
9/74
10/74
11/74
12/74
Hours Uoilcr
Operated
744
647
426
684
744
553
706
659
647
73B
632
744
Generation
Capacity (*X)
Not Available
Hours Module
Operated
0
0
110
495.
693
302
676
601
549
691
613
738
Hours Module Was
Required to Operate
Hours Module Was
Available to Operate
0
0
278
502
697
307
744
705
624
703
720
7A1
-------
For 111 |f 3
oo
FGD SYSTEM RELIABILITY INFORMATION
SYSTEM Will Cm.nrv MODULE A
Month/
Year
1/75
2/75
3/7b
4/75
5/75
6/75
7/75
8/75
9/75
10/75
11/75
12/75
Hours Boiler
Operated
685
666
609
638
744
642
689
565
720
194
0
0
Generation
Capacity (I)
Not Available
Hours Module
Operated
676
662
604
252
628
389
0
0
0
0
0
0
Hours Module Was
Required to Operate
Hours Module Was
Available to Operate
744
667
743
267
628
462
0
0
0
0
0
0
-------
Form
FGU SYSTEM RELIABILITY INFORMATION
MODULE A
SYSTEM mil rn,.nry
Mun Lit/
Year
1/76
2/76
3/76
4/76
5/76
6/76
7/76
8/76
Hours Dollar
Operated
0
0
309
692
665
612
588
495
Generation
Capacity (I)
Not Available
Hours Module
Operated
0
0
140
138
0
271
0
285
Hours Module Was
Required to Operate
309
692
665
612
588
495
Hours Module Was
Available Co Operate
0
0
224
166
0
374
192
731
-------
Form |J
ts>
o
FGD SYSTEM RELIABILITY INFORMATION
SYSTEM „,„ „ MODULE
y
Moil 111/
Year
1/72
2/72
3/72
4/72
5/72
6/72
7/72
8/72
9/72
10/72
11/72
12/72
Hours Boiler
Operated
121
628
640
525
649
649
690
46
0
226
719
Generation
Capacity (I)
Not Available
Hours Module
Operated
47
247
88
167
201
117
146
18
0
37
170
Hours Module Was
Required to Operate
Hours Module Was
Available to Operate
55
247
88
167
201
117
146
720
744
720
273
-------
Form f'J
KGD SYSTEM RELIABILITY INFORMATION
SYSTEM mn r»»nr MODULE R
ry
Month/
Year
1/73
2/73
3/73
4/73
5/73
6/73
7/73
8/73
9/73
10/73
11/73
12/73
Hours Boiler
Operated
568
672
656
614
735
512
677
668
553
738
633
627
Generation
Capacity (7.)
Not Available
Hours Module
Operated
64
110
70
84
0
0
0
0
0
0
0
0
Hours Module Was
Required to Operate
Hours Module Was
Available to Operate
64
110
70
84
-------
Komi 13
FGD SYSTEM RELIABILITY INFORMATION
SYSTEM u<11 r»..n...
MODULE
to
ttunth/
Yaar
1/74
2/74
3/74
4/74
5/74
6/74
7/74
8/74
9/74
10/74
11/74
12/74
Hours Boiler
Operated
744
647
426
684
744
553
706
659
647
738
632
744
Generation
Capacity (X)
Not Available
Hours Module
Operated
0
0
0
0
0
0
0
0
0
0
0
o
Hours Module Was
Required to Operate
Hours Module Was
Available to Operate
-------
Form
e
OJ
FGD SYSTEM RELIABILITY INFORMATION
SYSTEM Will County MODULE 8
Month/
Year
1/75
2/75
3/75
4/75
5/75
6/75
7/75
8/75
9/75
10/75
11/75
12/75
Hours Boiler
Operated
685
666
609
638
744
642
689
565
720
194
0
0
Ceiier.nl ion
Capacity (%)
Not Available
Hours Module
Operated
0
0
0
0
276
543
547
565
452
194
0
0
Hours Module Was
Required to Operate
Hours Module Was
Available to Operate
276
616
589
696
452
194
0
0
-------
l-'utui f J
FGD SYSTEM RELIABILITY INFORMATION
SYSTEM mil rv.nni
MODULE
Month/
Year
1/76
2/76
3/76
4/76
3/76
6/76
7/76
8/76
Hours lloiler
Operated
0
0
309
692
665
612
588
495
Generation
Capacity (7L)
Not Available
Hours Module
Operated
0
0
63
340
567
517
524
304
'
Hours Module Was
Required to Operate
Hours Module Was
Available to Operate
0
0
65
368
644
621
599
487
-------
rorm #1
FGD SYSTEM RELIABILITY INFORMATION
System Phillips
Start-Up Date 7/73
Number of Modules 4
Size of Modules (ACFM) 400,000
Total System Operating Hours
Total Boiler Hours in Period for which Data is Available
Total Hours System was Required to Operate
Total Hours System was Available to Operate
Longest Continuous System Operation
Average Load on System per Operating Hour
Maintenance Hours per Module per Week
125
-------
t'o rm § 3
FGD SYSTEM RELIABILITY INFORMATION
SYSTEM Phillips MODULE A
Month/
Ye ai-
l/75
2/75
3/75
4/75
V75
6/75
7/75
8/75
9/75
10/75
11/75
12/75
Hours Boiler
Operated
Generation
Capacity (Z)
Hours Module
Operated
AGO
478
57
607
626
360
Hours Module Was
Required to Operate
Hours Module Was
Available to Operate
-------
Form |3
FGD SYSTEM RELIABILITY INFORMATION
SYSTEM Phillips MODULE A
Month/
Year
1/76
2/76
3/76
4/76
5/76
6/76
7/76
8/76 1
J
Hours Boiler
Operated
Generation
Capacity (Z)
Hours Module
Operated
277
657
695
Hours Module Was
Required to Operate
-
Hours Module Was
Available to Operate
K9
-------
Fora |3
ho
oo
FGD SYSTEM RELIABILITY INFORMATION
SYSTEM Phillip* MODULE R
Month/
Year
1/75
2/75
3/75
4/75
5/75
6/75
7/75
8/75
9/75
10/75
11/75
12/75
Hours Boiler
Operated
Generation
Capacity (%)
•
Hours Module
Operated
180
682
561
207
720
661
Hours Module Was
Required to Operate
Hours Module Was
Available to Operate
-------
Form
FGD SYSTEM RELIABILITY INFORMATION
MODULE
SYSTEM Phllllpc
Month/
Year
1/76
2/76
3/76
4/76
5/76
6/76
7/76
8/76
Hours Boiler
Operated
Generation
Capacity (1)
Hours Module
Operated
536
662
353
Hours Module Was
Required to Operate
Hours Module Was
Available to Operate
-------
Komi f J
FGD SYSTEM RELIABILITY INFORMATION
SYSTEM Phillips MODULE C
Mouth/
'.'ear
1/75
2/75
3/75
4/75
5/75
6/75
7/75
8/75
9/75
10/75
11/75
12/75
Hours Boiler
Operated
Generation
Capacity (1)
Hours Module
Operated
537
323
685
505
0
182
Hours Module Was
Required to Operate
Hours Module Was
Available to Operate
CO
o
-------
Form
FGD SYSTEM RELIABILITY INFORMATION
SYSTEM Phtlltns MODULE g
Month/
Year
1/76
2/76
3/76
4/76
5/76
6/76
7/76
8/76
Hours Boiler
Operated
Generation
Capacity (t)
Hours Module
Operated
101
166
659
Hours Module Was
Required to Operate
Hours Module Was
Available to Operate
-------
Form
OJ
N3
FGD SYSTEM RELIABILITY INFORMATION
SYSTEM Phillips MODULE D (two-stage)
Moat.lt/
Year
1/75
2/75
3/75
4/75
5/75
6/75
7/75
8/75
9/75
10/75
11/75
12/75
Hours Boiler
Operated
Generation
Capacity (t)
Hours Module
Operated
723
319
536
487
75
386
Hours Module Was
Required to Operate
Hours Module Was
Available to Operate
-------
Form fJ
FGD SYSTEM RELIABILITY INFORMATION
SYSTEM pv,llino MODULE
tps
Month/
Year
1/76
2/76
3/76
4/76
5/76
6/76
7/76
8/76
Hours Boiler
Operated
Generation
Capacity (%)
Hours Module
Operated
707
406
401
Hours Module Was
Required to Operate
Hours Module Was
Available to Operate
M
OJ
to
-------
Form
FGD SYSTEM RELIABILITY INFORMATION
System Phillips Module A.B.C.&D
u>
Month/
Year
1/75
2/75
3/75
4/75
5/75
6/75
7/75
8/75
9/75
10/75
11/75
12/75
Hours Boiler Operated
boiler 01
83
354
463
547
16
172
Boiler 02
644
701
287
575
720
660
Boiler #3
703
454
669
620
688
709
Boiler #4
349
457
503
604
70
0
Boiler #5
605
517
672
681
720
689
Boiler #6
643
445
525
687
593
547
-------
Form
FGD SYSTEM RELIABILITY INFORMATION
System PMIHPQ Module A.a n.
to
Ln
Month/
Year
1/76
2/76
3/76
it/76
5/76
6/76
7/76
8/76
Hours Boiler Operated
Boiler #1
222
445
Boiler #2
722
588
Boiler *3
639
672
Boiler #4
0
0
Boiler *5
662
633
Boiler f6
661
571
-------
Form #1
FGD SYSTEM RELIABILITY INFORMATION
System LaCygne
Start-Up Date J/73
Number of Modules _j[
Size of Modules (ACFM) 340»000
Total System Operating Hours
Total Boiler Hours in Period for which Data is Available 11,481
Total Hours System was Required to Operate
Total Hours System was Available to Operate
Longest Continuous System Operation
Average Load on System per Operating Hour
Maintenance Hours per Module per Week _
136
-------
Form f3
u>
FGU SYSTEM RELIABILITY INFORMATION
SYSTEM i.a py£n» MODULE A
Month/
Year
1/74
2/74
3/74
4/74
5/74
6/74
7/74
8/74
9/74
10/74
11/74
12/74
Hours Boiler
Operated
364
364
0
332
500
480
313
571
606
662
386
0
Generation
Capacity (I)
0
0
Hours Module
Operated
179
239
0
222
344
441
236
514
417
472
347
0
Hours Module Was
Required to Operate
Hours Module Was
Available to Operate
-------
form §1
CO
FCD SYSTEM RELIABILITY INFORMATION
SYSTEM La Cvene MODULE A
touch/
Y-ar
1/75
2/75
3/75
4/75
5/75
6/75
7/75
8/75
9/75
10/75
11/75
12/75
Hours Holler
Operated
0
0
694
0
683
667
590
630
610
231
346
597
Genera C ion
Capacity (I)
0
0
41.1
0
55.9
56.4
50.0
49.5
41.7
12.5
28.7
46.8
Hours Module
Operated
0
0
0
Hours Module Was
Required to Operate
Hours Module Was
Available to Operate
613
704
632
583
555
565
492
668
675
-------
Korin |3
FGD SYSTEM RELIABILITY INFORMATION
SYSTEM La rypng MODULE A
vo
Month/
Year
1/76
2/76
3/76
4/76
5/76
6/76
7/76
8/76
Hours Boiler
Operated
618
594
6A3
0
436
Generation
Capacity (I)
50.7
55.4
56.7
0
Hours Module
Operated
0
Hours Module Was
Required to Operate
Hours Module Was
Available to Operate
638
654
687
7L4
670
699
684
-------
Form |3
FGD SYSTEM RELIABILITY INFORMATION
SYSTUM I-a ryf.ne MODULE g
Mouth/
Year
1/74
2/74
3/74
4/74
5/74
6/74
7/74
8/74
9/74
10/74
11/74
12/74
Hours Boiler
Operated
364
364
0
332
500
4BO
313
571
606
662
386
0
General: ion
Capacity (1)
0
0
Hours Module
Operated
115
247
0
233
415
402
252
512
532
402
273
0
Hours Module Was
Required Co Operate
Hours Module Has
Available to Operate
-------
Form |3
FGD SYSTEM RELIABILITY INFORMATION
SYSTEM La Cvene MODULE B
Month/
Year
1/75
2/75
3/75
4/75
5/75
6/75
7/75
8/75
9/75
10/75
11/75
12/75
Hours Boiler
Operated
0
0
694
0
683
667
590
630
610
231
346
597
Generation
Capacity (%)
0
0
41.1
0
55.9
56.4
50.0
49.5
41.7
12.5
28.7
46.8
Hours Module
Operated
0
0
0
Hours Module Was
Required to Operate
Hours Module Was
Available to Operate
714
633
615
667
655
602
675
654
650
-------
Form fJ
FGD SYSTEM RELIABILITY INFORMATION
SYSTEM La Cygne MODULE ^_
10
Mui.th/
Year
1/76
2/76
3/76
4/76
5/76
6/76
7/76
8/76
Hours lioiler
Operated
618
594
643
0
A 36
Generation
Capacity (X)
50.7
55. A
56.7
0
Hours Module
Operated
0
Hours Module Was
Required to Operate
Hours Module Was
Available to Operate
630
628
667
684
677
707
692
-------
Km in f 3
FGD SYSTEM RELIABILITY INFORMATION
SYSTEM _La_Cjrgnfi MODULE c
Mouth/
Year
1/74
2/74
3/74
4/74
5/74
6/74
7/74
8/74
9/74
11/74
12/74
Hours (toiler
Operated
364
364
0
332
500
480
313
571
606
662
386
0
Genei'atiou
Capacity (2)
0
0
Hours Module
Operated
161
213
0
249
390
400
256
415
444
391
230
0
Hours Module Was
Required to Operate
Hours Module Was
Available to Operate
-------
KCI) SY.'ITKM KKI.I Altll.lTY 1NRIKMAT ION
SYSTEM
La Cyguc
MOIMII.K
Mt.nl li/
Y.-.ii
!•/'/!>.
2//5
:«/75
/./7b
b/7-j
6//b
7//b
8//'j
9/?b
JO//^
ll.//-1*
12/71)
lloni :; Itui 1 er
()|x-i ,il eil
U
0
6%
U
68 J
GO;
b'JO
6 JO
610
231
3/i6
597
Ccncial ion
Capacity (7L)
0
U
/• 1.1
U
5i.9
bfa.4
50.0
49.5
/,! .7
12.5
2H. 7
^.6.8
Itotiru Moilule
Opuriil oil
0
0
.
0
Hours Morlule Wau
Ke(|iiiroil to O|>eiule
Hours Moilulu \liia
Avallalilc- lo Operalf
G'i(>
701
604
667
64V
607
344
577
602
-------
Form |li
SYSTEM
SYSTKM RELIABILITY INFORMATION
MODULE f.
Mouth/
Ye in
1/76
2/76
3/76
4/76
5/76
6/76
7/76
8/76
lours IJoiler
Operated
618
594
643
0
436
General, ion
Capacity (1)
50.7
55.4
56.7
0
Hours Module
Operated
0
Hours Module Was
Required to Operate
Hours Module Was
Available to Operate
675
597
658
692
677
684
685
-------
l-'onu 13
KGU SYSTEM RELIABILITY INFORMATION
SYSTEM ^ CyEne MODULE D
Moith/
Ye. r
1/74
2/74
1/74
4/74
5/74
6/74
lllk
8/74
9/74
10/74
11/74
12/74
Hours Boiler
Operated
364
364
0
332
500
480
313
571
606
662
386
0
General ion
Capacity (I)
0
0
Hours Module
Operated
315
278
0
293
426
433
253
460
458
535
235
0
Hours Module Was
Required to Operate
Hours Module Was
Available to Operate
-------
Form |J
KGD SYSTEM RELIABILITY INFORMATION
SYSTEM La Cygne MODULE D
Month/
Ye a i
1/75
2/75
3/75
4/75
5/75
6/75
7/75
8/75
9/75
10/75
11/75
12/75
Hours Boiler
Operated
0
0
694
0
683
667
590
630
610
231
346
597
Generation
Capacity (%)
0
0
41.1
0
55.9
56.4
50.0
49.5
41.7
12.5
28.7
46.8
Hours Module
Operated
0
0
0
Hours Module Was
Required to Operate
Hours Module Was
Available to Operate
570
666
611
623
580
610
548
671
634
-------
l''onu 13
VGD SYSTEM RELIABILITY INFORMATION
SYSTEM
- t.a Cygne
MODULE
oo
Month/
Year
1/76
2/76
3/76
A/76
5/76
6/76
7/76
8/76
Hours Bo i lei
O|>crat e
-------
fr'o i m f !1
FCD SYSTEM RELIABILITY INFOKMATIUN
SYSTEM ,a ,,„,.„„ MODULE j.
Moil 111/
Year
1/74
2/74
3/74
4/74
5/74
6/74
7/74
8/74
9/74
JO/74
11/74
12/74
llouru Holler
Operated
364
364
0
332
500
480
313
571
606
662
386
0
Generation
Capacity (1)
0
0
Hours Module
Operated
83
189
0
245
389
393
266
463
503
520
324
0
Hours Module Was
Required to Operate
Hours Module Was
Available to Operate
-------
l-'onn fj
FGD SYSTEM RELIABILITY INFORMATION
SYSTKM
La Cygno-
MODULE
Ui
o
Month/
Year
1/75
2/75
3/75
4/75
5/75
6/75
7/75
8/75
9/75
10/75
11/75
12/75
Hours lioiler
Operated
0
0
694
0
683
667
590
630
610
231
346
597
Generation
Capacity
-------
b'GD SYSTEM RELIABILITY INFORMATION
SYSTEM
Tygn
MODULE
Munlli/
Year
1/76
2/76
3/76
4/76
5/76
6/76
7/76
8/76
Hours Boiler
Operated
618
594
643
0
436
Generation
Capacity (Z)
50.7
55.4
56.7
0
Hours Module
Operated
0
Hours Module Was
Required to Operate
Hours Module Was
Available to Operate
624
638
701
662
670
692
684
-------
Form
ro
FGD SYSTEM KEL1AKI1.ITY INFOKMAT1ON
SYSTEM i.^ rnt.MODULE £
Mouth/
Yoar
1/74
2/74
3/74
4/74
5/74
6/74
7/74
8/74
9/74
10/74
11/74
12/74
lluurs Ituiler
Operated
364
364
0
352
500
480
313
571
606
662
386
0
Generation
Capacity (I)
0
0
lluurs Module
Operated
133
364
0
332
422
396
248
448
539
615
327
0
Hours Module Was
Required to Operate
Hours Module Was
Available to Operate
-------
Form
b'GD SYSTBH KKLIMUUTY INFORMATION
SYSTEM i.n r.yEn»
MODULE
MonLh/
Year
2/75
3/75
4/75
5/75
6/75
7/75
8/75
9/75
10/75
11/75
12/75
Hours lioiler
Operatcd
0
0
694
0
683
667
590
630
610
231
346
597
Generation
Capacity (T.)
0
0
41. i
0
55.9
56.4
50.0
49.5
41.7
12.5
28.7
46.8
Hours Module
Operated
0
0
0
Hours Module Was
Required to Operate
Hours Module Was
Available to Operate
681
664
620
650
632
559
544
644
659
-------
FGD SYSTEM RELIABILITY INFORMATION
SYSTliM Ia Cygne MODULE
in
Mnnlli/
.'ear
1/76
2/76
3/76
4/76
5/76
6/76
7/76
8/76
Hour:; lioi Ler
Operated
618
594
643
0
436
Generation
Capacity (1)
50.7
55.4
56.7
0
Hours Module
Operated
0
Hours Module Was
Required to Operate
Hours Module Was
Available to Operate
612
648
679
707
670
699
670
-------
t'utw
U1
Ul
SYSTEM HEV,lABlLm INFORMATION
SYSTEM La Cygne MODULE R
Month/
Ycitr
1/74
2/74
3/74
4/74
5/74
6/7 ft
7/74
8/74
9/74
10/74
11/74
12/74
Hours Boiler
Operated
364
364
0
332
500
480
313
571
606
662
386
0
Generation
Capacity (71)
Hours Module
Operated
295
237
0
291
399
418
241
507
518
588
323
0
Hours Module Was
Required to Operate
Hours Module Was
Available to Operate
-------
Form |J
Ln
FGD SYSTEM RELIABILITY INFORMATION
SYSTEM Ta p.,..M MODULE r.
Month/
Ye.ir
__2_/_75_
_3/75
4/75
5/75
6/75
7/75
8/75
9/75
10/75
11/75
12/75
Hours Uoilfcr
Operated
0
0
694
0
683
667
590
630
610
231
346
597
Generation
Capacity (Z)
0
0
41.1
0
55.9
56.4
50.0
49.5
41.7
12.5
28.7
46.8
Hours Module
Operated
0
0
0
Hours Module Was
Required to Operate
Hours Module Was
Available to Operate
665
620
638
634
618
534
481
676
622
-------
Kti 1111 J J
Ln
SYSTICM
d) SYSTEM ttELlAlllLlTY IN FORMAT ION
La Cvgne __ MODULI! ___ £ ____
Y«NI
mli/
in
1/76
2/76
3/76
4/76
5/76
6/76
7/76
8/76
Hours lioilur
Operated
618
594
643
0
436
General ion
Capacity (7.)
50.7
55.4
56.7
0
Hours Module
Operated
0
Hours Module Was
Required to Operate
Hours Module Was
Available to Operate
627
658
680
714
655
699
655
-------
Form #1
FGD SYSTEM RELIABILITY INFORMATION
System
Green River
Start-Up Date 9/13/76
Number of Modules 1
Size of Modules (ACFM) 360»000
Total System Operating Hours 5426
Total Boiler Hours in Period for which Data is Available 5201
Total Hours System was Required to Operate JJ049
Total Hours System was Available to Operate
Longest Continuous System Operation
Average Load on System per Operating Hour
Maintenance Hours per Module per Week
158
-------
Km in
vo
FGD SYSTEM RELIABILITY INPOKMAT10N
SYSTEM r,roon K
-------
Form tfJ
KCU SYSTEM RKLIAUILITY INFOWHATION
Riwr
MODULE
Mouth/
YC.-II-
1/76
2/76
3/76
A/76
5/76
6/76
7/76
8/76
9/76
s lloiler
•c rated
572
499
450
552
456
597
587
744
571
Generation
Capacity (%)
Hours Module
Operated
64
211
386
552
456
589
577
722
571
Hours Module Was
Required to Operate
456
499
409
552
456
596
587
744
571
Hours Module Was
Available to Operate
312
486
722
648
606
720
666
722
617
-------
form #1
FGD SYSTEM RELIABILITY INFORMATION
System Paddy's Run
Start-Up Date 4/73
Nunfoer of Modules 2
Size of Modules (ACFM) 175.000 (355°F)
Total System Operating Hours
Total Boiler Hours in Period for which Data is Available
Total Hours System was Required to Operate
Total Hours System was Available to Operate
Longest Continuous System Operation
Average Load on System per Operating Hour
Maintenance Hours per Module per Week ______________
161
-------
fun SYSTEM Kin.lAliH. 1TY INlOKMATiON
SYSTEM Paddy's Run MODULE A
to
l> Mil ill/
Y.'ut
4/73
5/73
6/73
7/73
8/73
9/73
10/71
H/73
12/73
Hours lini lor
Operated
320
267
253
238
330
388
6B2
720
192
Generation
Capacity (71)
Hours Module
Operated
60
30
3
50
175
333
340
249
83
Hours Module Was
Required to Operate
Hours Module Was
Available to Operate
-------
form
u>
KGD SYSTEM RELIABILITY INFORMATION
SYSTEM Pa,^y-s B..n MODULE A
Month/
Year
1/74
2/74
3/74
4/74
5/74
6/74
7/74
8/74
9/74
10/74
11/74
12/74
Hours Boiler
Operated
Generation
Capacity (%)
OperabilttyOl
0
0
0
0
0
o
51
50
0
100
0 .
0
Hours Module Was
Required Lo Operate
Hours Module Was
Available to Operate
-------
KOI-UI |3
FGD SYSTEM RELIABILITY INFORMATION
SYSTEM Paddy's R..n MODULE A
Month/
You r
1/75
2/75
3/75
4/75
5/75
6/75
7/75
8/75
9/75
10/75
11/75
J2/75
Hours Boiler
Operated
Generation
Capacity (I)
Operability(TL)
0
0
0
0
0
0
0
0
100
100
100
90
Hours Module Was
Required to Operate
Hours Module Was
Available to Operate
-------
Kortu
en
Un
FGD SYSTEM RELIABILITY INFORMATION
SYSTEM _E*ddy^_Run_
Month/
Ye.-ir
1/76
2/76
3/76
4/76
5/76
6/76
7/76
8/76
9/76
10/76
11/76
12/76
Hours Boiler
Operated
Generation
Capacity (%)
Operabillty(7.)
100
0
0
0
100
100
100
100
Hours Module Was
Required to Operate
Hours Module Was
Available to Operate
-------
Form f'J
FGD SYSTEM RELIABILITY INFORMATION
SYSTEM Padd's Run MODULE^
Monlh/
Yuar
4/73
5/73
6/73
7/73
8/73
9/73
10/73
11/73
12/73
Hours Boiler
Operated
320
267
253
238
330
388
682
720
192
Generation
Capacity (Z)
Hours Module
Operated
190
175
15
50
213
279
637
720
151
Hours Module Was
Required to Operate
Hours Module Was
Available to Operate
-------
Form |3
FGD SYSTEM RELIABILITY INFORMATION
SYSTEM Pj,My-G p.m MODULE B
Month/
Year
1/74
2/74
3/74
4/74
5/74
6/74
7/74
8/74
9/74
10/74
11/74
12/74
Hours Holler
Operated
Generation
Capacity (7L)
Operabilitya)
0
0
0 ,
0
0
0
81
77
o •
100
0
0
Hours Module Was
Required to Operate
Hours Module Was
Available to Operate
-------
Form |3
FCD SYSTEM RELIABILITY INFORMATION
SYSTEM PaHHy-g B..n MODULE _B
o\
oo
Monl.h/
Year
1/75
2/75
3/75
4/75
5/75
6/75
7/75
8/75
9/75
10/75
11/75
12/75
Hours Boiler
Opera Led
Generation
Capacity (1)
Operablllty(7.)
0
0
0
0
0
0
0
0
100
100
100
90
Hours Module Was
Required to Operate
Hours Module Was
Available to Operate
-------
Kuriu
l-'GD SYSTKM RELIABILITY INFORMATION
SYSTEM p^.i'* B,m MODULE R
o\
lontli/
(ear
1/76
2/76
3/76
4/76
5/76
6//6
7/76
8/76
Itours Boiler
Operated
Generation
Capacity (7.)
Operabillcy(7.)
100
0
0
0
100
100
100
100
Hours Module Was
Required Co Operate
liuurs Module Was
Available to Operate
-------
GRAPHICAL REPRESENTATION
OF FGD SYSTEM PERFORMANCE
170
-------
too
I .0
AVf MkOX MCUAM.ITV i tl.f»
10 It
II m if
t MOM ITMT-UT UNMTIMI
40 4* (0 SS
Figure C-l. Cholla FGD System Reliability - Module A.
-------
70
j go
to
•VENAOC MLMM.ITY • ST. I*
30
10
10 M 30
TIME rNOM STAHT-UP IMOMTHSI
40 41
Figure C-2. Cholla FGD System Reliability - Module B.
-------
CO
M 30 It
TIMC HUM STAMT-UP IMONTNSI
Figure C-3. Will County FGD System Availability - Module A.
-------
AVERAGE AVAILABILITY FOB PAST 1* MONTHS • 47.S»
AVCHAOC AVAtt.AON.ITY FOR FMIST It MONTHS - »».«»
MODULE S WAS NOT OFtBATED DUWNO THIS PEMOO.
IFrOATS WERC CONCENTMATEO ON MODUtE A AMD
EXTENSIVE MODIFICATIONS WEME MADE TO MOOW.C •
CO X* 30
TIME FROM START-UP IMONTHSI
Figure C-4. Will County FGD System Availability - Module B.
-------
Ln
to it
40 4t
TIMf FROM •TAMT-UP (MONTHS!
Figure C-5. Will County FGD System Operability - Module A.
-------
> «0
30-
AVERAOC OPCRABIUTY . II.O»
Z* 30 31
FHOM STAHT-IW IUOMTH8I
Figure C-6. Will County FGD System Operabillty - Module B.
-------
10
10
30 at
TIME FROM START-UP IMOMTH8I
Figure C-7. Will County FGD System Utilization - Module A.
-------
TO-
00
so-
AVBfMOC UTN.IIATION •
*• M at
mie mow STAMT-W IMOMTMM
41 SO
Figure C-8. Will County F6D System Utilization - Module B.
-------
80
AVEMOC UTILIZATION • 6O.1t
VI
VO
«0 II
20 3» tO
TIME PROM f TABT-OF IUONTHSI
4* tO
Figure C-9. Phillips FGD System Utilization - Average Modules A.B&C.
-------
00
O
to-
TO
2
I •••
3
40
AVMAW UTItlZATMN • •!.•*
!•
M
*l M M
TIM rHOM •TANT-UT IMONTNW
•0 C»
Figure C-10. Phillips FGD System Utilization - Module D.
-------
£
5
2 .o
oo
to
AVMAtt AVMIAMUTV . M.<«
*•
tl *•
TIMC riMM «TMIT-W> IMMmMI
Figure C-ll. La Cygne FGD System Availability - Average All Modules.
-------
AVCRAOE OPCRABILITY - T«.3»
00
N>
SO-
tl 30 It
TIM FROM »TAHT-U» (MON1HM
4» CO
Figure C-12. La Cygne FGD System Operability - Average All Modules.
-------
to»
s
U)
AWIMM AVMLAMUT* • •*.««
M
M
Figure C-13. Green River FGD System Availability.
-------
*°
-I SO
00
AVCNAQC «EU»»IUTY . (4.3*
t« It 30
TMM FM>« tTAHT-UP IHODtHSI
»» 40 41 10
Figure C-14. Green River FGD System Reliability.
-------
00
l-n
AVERAOE OPERABILITY . 10.8*
10 It
10 it 30 36
TIME FHOU ITAMT-U* IMONTHII
4f SO
Figure C-15. Green River FGD System Operability.
-------
•o
•o
oo
30-
AVCKAM UTH.UATIOM . •!.•«
M
M M *•
TM1 rHOW ITABT-UT MKMTMW
41 M
Figure C-16. Green River FGD System Utilization.
-------
oo
-I—
to
- 41 «»
t* SO
TNM FHOM (TAUT-OP (MONTH*!
if *•
41
Figure C-17. Paddy's Run FGD System Operability - Average Modules A&B.
-------
CD
00
AVMAOB tmUMTKW • M.*%
M *•
TMtt FNOM STMT-W IMOMnMI
Figure C-18. Paddy's Run FGD System Utilization - Average Modules A&B.
-------
CALCULATIONS
189
-------
CALCULATIONS
Availability Range
Availability - A Will County - 43.55
LaCygne * 88.1
Green River - 82.6
Average - 71.35
C2 - h [(43.35-71.35)2 + (88.1-71.35) + (82.6-71.35)2]
A2 784+280.6+126.6 ___ ,
U m . * DiO.D
a2 - 24.4
Case 1. 90% Confidence Level t - 2.92
99Z Confidence Level t - 9.925
!. /71.35 - (2-92)(24.4)\ < A < ^71.35 + (^.92)(24.4)\
30.2 < A < 100
I
2
. /7L35 - <^925)(24.4)V A < I + (9.925) (24.4)
V /y )- - \ ST •
0 < A < 100
190
-------
Reliability Range
Reliability = R Cholla 92.2
Green River =84.3
Average - 88.25
a2 = [(92.2-88.25)2 + (84.3-88.25)2]
a2 - 15.6 + 15.6 -31.2
a2 5.6
Case 1. 90% Confidence Level t - 6.314
99% Confidence Level t - 63.66
.25 - (6-314)(5.6) \ < R < L^ 25 + (6.314) (5.6)'
|88
63.2 R 100
1.25 - (63.66) (5.6)\ < R < / + (63.66) (5.6)
0 < R < 100
191
-------
Operabillty Range
Operability - 0 Will County - 20.5
Green River - 80.8
Paddy's Run - 41.8
Average -47.7
a2 - % [(20.5-47.7)2 + (80.8-47.7)2 -I- (41.8-47.7)21
a2 - h [739.8 + 1095.6 + 34.8] - 935
S2 - 30.57
Case 1. 90Z Confidence Level t - 2.92
99Z Confidence Level t - 9.925
i I,-, i (2.92)(30.57)\ < n < {.- 7 . (2.92)(30.57^
1. iH/.f— J_—I
\ /1": / v *T
0 < 0 < 99
2.
/I"
0 < 0 < 100
101 L 7 , (9.925)P0.57)\
192
-------
Utilization Range
Utilization = U
Will County =25.0
Phillips =61.3
LaCygne = 76.3
Green River = 51.0
Paddy's Run = 28.3
a =
cr =
Average
48.4
1(25-48.4)2 + (61.3-48.4)2 + (76.3-48.4)2 + (51-48.4)2 +
(28.3-48.4)2 |
[547.6 + 166.4 + 778.4 + 6.8 + 404] = 475.8
a = 21.8
Case 1. 90% Confidence Level t = 2.132
99% Confidence Level t = 4.604
. 48.4 .
(2.132X21.8)
(2.132)(21.8)
/T"
2.
27.6 U 69.2
3.5 < U < 93.3
(4.604)(21.8)
193
-------
APPENDIX D
FGD SYSTEMS
194
-------
D.I CHOLLA GENERATING STATION
The Cholla Power Generating Station of the Arizona Public Service
Company is located near Joseph City, Arizona. The Cholla Station consists
of a 126 MW coal-fired boiler which has been retrofitted with an FGD system.
The boiler, which is of Combustion Engineering design and manufacture, has
been in operation since 1962.
The FGD system is a limestone slurry scrubbing process which was
designed by Research-Cottrell and placed in service in 1973. The system
consists of two scrubbing modules, limestone slurrying equipment and a waste
disposal pond. Figure D-l is a schematic of the FGD system and Table D-l
illustrates the operating characteristics of the boiler-scrubber system.
A Research-Cottrell multicyclone collector is located between the
boiler and the FGD system. This device operates with an efficiency of 75
percent to provide primary control of particulate emissions from the boiler.
The two scrubber modules which comprise the FGD system are each capable
of processing 240,000 acfm or about 50 percent of the maximum flue gas flow
from the boiler. However, the two modules are not identical. Module A
consists of a flooded-disc venturi prescrubber in series with a packed
tower absorber while Module B is comprised of an identical prescrubber in
series with a spray tower absorber. Module A circulates limestone slurry
in the absorber while the B absorber circulates makeup water.
Ground limestone for the FGD system is purchased from two suppliers,
both located in Arizona. Because the plant has no limestone milling facility
the finely ground limestone is stored in a silo. A small limestone slurry
mixing tank is provided at the base of the tower.
195
-------
VO
U«»tOIM
Slvrrylnc Tmk
Figure D-l. Cholla FGD Systaa.
-------
TABLE D-l. OPERATING CHARACTERISTICS OF THE CHOLLA BOILER-SCRUBBER SYSTEM
Item
1. Boiler
2. Fuel
3. Paniculate Control
4. Absorbent/Preparation
5. SO; Control
6. FGD System
7. Demlster
Description
The power station has one dry-bottom pulvericed-coal-f Ired
boiler which has been operating since 1962. The unit Is base
load operated and has historically had trouble-free operation.
A low-sulfur coal Is burned at the power plant.
A Research-Cottrell nultlcyclone-type collector provides
primary control of partlculate emissions. The FGD system
also removes partlculates from the gas stream.
Limestone la used to absorb SO: from the gas. Finely ground
limestone IB purchased fron a mine near Klngman, Arizona.
No Billing facilities are at the Cholla station.
The FGD system Is used to control SOt emissions In order to
comply with air quality regulations. '
The FGD system consists of two scrubbing modules (A and B) ,
each handling 50 percent of the boiler's flue gas load.
Module A Is packed and circulates limestone slurry
Module B is a spray-tower which circulates make-up water.
A two-stage, polypropylene slit demlster Is located In the
Parameter
Pover Rating
Gross
Net Without FGD
Met With FCD
Average Capacity Factor
Sulfur Content
Ash Content
Beating Value
Removal Efficiency
Multicyclone
FGD system
Composition
Stolchlometry
Removal Efficiency
System Vendor
Type
Start-up Date
Prescrubber type
1
Module Sice
Demlster wash
Value
126 HU
115 Mi
112 HW
90 percent
0,55 percent
10.4 percent
10,290 Btu/lb
75 percent
97 percent
1.1
58.5 percent
Reaearch-Cotrell
Retrofit
7/73
Flooded-Dlac, Variable Throat
Venturl
260,000 acfm 9 276*F
-
8. Fan
9. Reheater
10. Sludge Disposal
11. Water Make-Up
upper section of both A and B absorbers. The demlsters
are washed Intermittently from above and below with freah
water sprays .
A forced-draft booster fan Is located upstream of the
venturl prescrubber on each module.
The desulfurlzed flue gas Is reheated aa it passed through
two shell-ami-tube heat exchangers. Heat la supplied by
200 psig steam.
The plant has no sludge treatment or fixation systems.
The sludge Is pumped to the fly ash disposal pond on an
intermittent basis. Because of light rainfall and a high
evaporation rate in this area, no liquor is reclrculated
from the pond.
Ho water Is recycled from the sludge disposal pond to the
FGD system. Make-up water for the aystem la boiler water
blowdown.
System Pressure Drop
Flue Gas Temperature
Inlet
Outlet
Pond/Landfill
Requirements
Fresh Water Make-Up
25 In H20
121*F
165*F
-------
Flue gas entering the FGD system is split between the two modules. Most
of the particulates remaining in the gas are removed by the prescrubbers. In
the A absorber, flue gas flows through packing made of corrugated sheets of
polypropylene. The packing promotes intimate contact between the flue gas
and the circulating limestone slurry. Approximately 92 percent of the SOa
in the flue gas which enters Module A is absorbed by the slurry. In the B
absorber, flue gas is contacted with water sprays which absorb about 25 per-
cent of the SOa which enters the module.
Overall, the Cholla FGD system removes nearly. 58 percent of the flue gas
SOz. However, since the boiler is burning 0.55 percent sulfur coal, the
quantity of SO2 scrubber is only about 12 Ibs S02 per ton of coal burned.
This compares to other FGD systems which remove 72 to 180 Ibs S02 per ton of
coal burned.
Prior to leaving the absorbers, the flue gas passes through a two-stage
demister which removes entrained droplets from the gas stream. The demisters
are washed intermittently with fresh water to prevent plugging.
Spent scrubbing liquor from both modules is pumped to a recirculation
tank. Most of this is recycled to the venturi prescrubbers. However, a
purge stream is intermittently withdrawn from the recirculation tank and
pumped directly to the sludge disposal pond.
A unique feature of the Cholla FGD system is its open loop mode of
operation. This means that no water is recycled from the sludge pond to the
scrubbing system. This type of operation is possible because of the high
evaporation rate at the plant site.
Operation in the open loop mode reduces the possibility of sulfite/
sulfate scaling in the FGD system. This in turn results in more reliable
FGD system performance.
198
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D.2 WILL COUNTY GENERATING STATION
The Will County Power Generating Station of Commonwealth Edison Company
is located on the Chicago Sanitary and Ship Canal near the town of Romeoville,
Illinois. An FGD system has been retrofitted on Unit No. 1 at the Will
County Station. This unit is a 167 MW, wet-bottom, coal-fired boiler which
was manufactured by Babcock and Wilcox and installed in 1955. The boiler is
a cycling-load unit with an average capacity factor of 53 percent.
The FGD system is a limestone slurry scrubbing process designed and
manufactured by Babcock and Wilcox and placed in service in February, 1972.
The system consists of two scrubber modules, limestone handling and milling
facilities, and a sludge treatment and stabilization unit. The system
operates closed-loop with respect to process water. Fresh water is used
only to replace evaporative losses and water retained in the sludge.
Flue gas flows from Unit 1, through an ESP, to the FGD system. The ESP,
which has an actual removal efficiency of 79 percent, is used only when the
FGD system is out of service.
Flue gas enters the FGD system and is split between the two scrubber
modules. Each module is designed for 385,000 acfm throughput which is equi-
valent to one-half of the maximum flue gas flow from the boiler. The scrub-
ber modules are comprised of a venturi prescrubber in series with a two-stage
perforated tray absorption tower. Figure D-2 is a schematic of the FGD
system and Table D-2 details the operating characteristics of the Will County
boiler-scrubber system.
The flue gas entering the FGD system first flows through the venturi
prescrubber. In the venturi, most of the participates are removed from the
gas as it is contacted with jets of limestone slurry sprayed from high
pressure nozzles.
199
-------
to
O
o
Figure D-2. Will County FGD System.
-------
TABLE D-2. OPERATING CHARACTERISTICS OF THE WILL COUNTY UNIT NO. 1 BOILER-SCRUBBER SYSTEM
Item
N5
1. Boiler
2. Fuel
3. Partleulate Control
4. Absorbent Preparation
5. SOi Control
6. FCD System
7. Demister
8. Fan
Descrlpt Lon
Unit No. 1 of the Will County Power Generating Station
Is a wet-bottom, coal-fired boiler which has been retro-
fitted with an FGD system. The boiler was nanufactured
by Babcock and Wllcox and installed In 1955.
Medlm Sulfur Coal
The FGD system Is used as the primary means of control-
ling participates. An electrostatic preclpltator-(ESP)
manufactured by Joy Western Precipitation Division is
used when the FGD system Is Inoperable.
Limestone slurry absorbs SO 2 from the flue gas. The
limestone milling facilities consist of a limestone
rock conveyer, two 260-ton limestone bunkers, two wet
ball mills, and a slurry storage tank.
The FGD system Is used to control SO; emissions In
order to meet air quality regulations.
The FGD system consists of tvo Identical nodules, each
capable of processing 50 percent of the maximum flue
gas Clow from the boiler. The FGD modules are com-
prised of s venturl prescrubber In series with a two-
stage perforated tray absorber.
A two-stage, chevron-type demister Is located 7 feet
above the second absorber-tray. The demister Is
Parameter
Power Rating
Gross
Net Without FGD
Net With FGD
Average Capacity Factor
Sulfur Content
Ash Content
Heating Value
Removal Efficiency
FGD System
ESP
Composition
Silica
Calcium Carbonate
Magnesium Carbonate
Other
Stolchiometry
Removal Efficiency
System Vendor
Type
Start-up Date
Module A
Module B
Prescrubber Type
Module Size
Demister Wash
Top
Value
167 MU
153 MM
146 MU
52.8 Percent (1973)
2.14 Percent
10.0 Percent
9463 Btu/lb
98.0 Percent Removal
79.0 Percent Removal
0.5 Percent
97 . 5 Percent
1 . 0 Percent
1.0 Percent
1.3 - 1.5
82 - 90 Percent
Babcock and Wlleox
Retrofit
4/72
2/72
Variable Throat Venturl
385,000 acfm 9 355* P
3,000 gpm Pond Supernatant/
washed continuously from below and Intermittently
from above. Demlsters are constructed of fiber rein
forced plastic.
There Is an induced draft (ID) fan located at the
reheater outlet on each module. These ID fans are
In series with the boiler ID fans.
Bottom
System Pressure Drop
40 sec. every hr.
120 gpm Fresh Water/Continuous
25 in. HjO
-------
Item
TABLE D-2. (Continued)
Description
Parameter
9. Reheatcr
10. Sludge Disposal
11. Water Makeup
The gun exiting the absorber in reheated by a bare
tube teheater comprised of 9 sections. The bottom
three sections are stainless steel and the other
six sections are of corten steel construction. Each
reheater has four soot blowers. Heat Is supplied by
saturated steam at 350 pnig pressure.
Sludgp In fixed by mixing with line and fly ash.
Approximately 200 Ibs of line ami 400 Ibs of fly
ash are required to stabilize 1 ton of sludge (dry
basis).
Both fresh water and recycle pond water are used in
the system. However, It is a closed-loop system.
Flue Gas Temperature
Inlet
Outlet
Fond/Landfill
Requirements
Fresh Water Makeup
128°F
165°F
150 Acre - ft/yr
300 gpm
O
r-j
-------
After passing through the venturi, the flue gas enters a sump where
entrained slurry droplets are removed. The gas then flows upward through
the SO2 absorption tower and passes through two perforated trays. The trays,
which are wetted with limestone slurry sprays, provide an extended wetted
surface for absorption of SO2 by the circulated slurry.
The absorption tower is fitted with a two-stage, Z-shaped demister. As
flue gas flows through the demister, fine mist droplets coalesce on the sur-
face of the demister vanes and drip back into the tower. The demister is
equipped with two sets of wash water headers. The lower demister is washed
continuously from below by 125 gpm of fresh water. It is also washed inter-
mittently from above by 3000 gpm of pond water for 30 seconds every two hours.
Flue gas leaves the absorber/demister and enters the reheater unit,
where its temperature is raised from 128°F to about 165°F. Reheat is neces-
sary to prevent condensation in the fans, ducts, and the existing bricklined
stack. The reheat also imparts plume buoyancy to suppress plume visibility.
Limestone for the FGD system is received in coarse ground form and is
finely ground in two wet ball mills. A limestone slurry is discharged from
the mills and piped to a storage tank which supplies the scrubber modules.
Spent limestone slurry is withdrawn continuously from the venturi recircu-
lation loop (Figure D-2) and discharged to a 65 foot diameter thickener.
Thickener overflow is pumped directly to the scrubber sludge pond while the
underflow is stabilized by mixing it with lime and fly ash. Overflow from
the sludge pond is then returned to the recirculation tanks for reuse in the
system. The stabilized sludge is transported by concrete mixing trucks to a
small, on site, clay-lined basin where it solidifies in about one week.
D.3 PHILLIPS GENERATING STATION
The Phillips Power Generating Station of the Duquesne Light Company is
located on the Ohio River, 20 miles northwest of Pittsburgh, Pennsylvania.
The Phillips Station consists of six dry-bottom, pulverized-coal-fired boilers
203
-------
which have a generating capacity of 413 MW. All of the boilers were
manufactured by Foster-Wheeler and installed during the period 1942 to 1957.
The entire Phillips Station has been retrofitted with a Chemico FGD system
which began operation in July, 1973.
The FGD system consists of four venturi scrubbers, a second stage
absorber, line slaking equipment, and sludge treatment and disposal facili-
ties. The FGD system is supplemented by particulate removal equipment.
This equipment consists of Research-Cottrell mechanical collectors in series
with a Research-Cottrell ESP on each boiler. Figure D-3 is a. schematic of
the FGD system and Table D-3 details the operating characteristics of the
Phillips boiler-scrubber system.
In operation, flue gas from the six boilers is treated by the particu-
late collection equipment and then routed into a common duct. The four
venturi scrubbers are tied into this same duct to provide for flexible
system operation. Each venturi processes 547,000 acfm which amounts to about
one quarter of the maximum flue gas flow from the boilers. These scrubbers,
which circulate process water treated with lime, provide final particulate
removal while removing 50 percent of the flue gas 862 . Overall particulate
removal efficiency for the entire mechanical collector ESP scrubber system
is 99 percent.
Before exiting the venturi scrubbers, the flue gas enters a spray-
washed mist eliminator which removes entrained slurry from the flue gas.
The gas leaves the scrubber, passes through a booster induced draft fan and
then follows one of two pathways.
In the case of the three single-stage scrubber trains the gas enters a
second demister which removes any remaining slurry entrained in the flue gas.
The gas is then reheated and exhausted to the atmosphere through the stack.
204
-------
NJ
O
Ul
Cl.f
Ornrf
c^
I
rX
| so,
Ab.orb.r
^
^
Figure D-3. Phillips FGD System.
-------
TABLE D-3. OPERATING CHARACTERISTICS OF THE PHILLIPS BOILER-SCRUBBER SYSTEM
N>
o
Item
1. Boiler
2. Fuel
3. Particulate Control
4. Absorbent Preparation
5. SO: Control
6. FGD System
Descr Ipt ion
The Phillips Station consists of six dry-bottom,
pulverized coal-fired boilers. The entire station
has been retrofitted with an FGD system. The boilers
were manufactured by Foster-Wheeler and Installed during
the period 1942 to 1956.
Medium-sulfur coal is burned In the boiler.
Partlculates are controlled by Research-Cottrell
Mechanical Collectors In series with electrostatic
preclpltators. The FGD system also removes partlculates
from the flue gas.
Lime is used to absorb the SO2 . Lime Is fed from a storage
silo at a controlled rate to a lime slaker where It Is mixed
with fresh makeup water. The slaked lime overflows to a
slaker transfer tank where makeup water is added to provide
a constant flow of lime slurry with a 15 percent solids
concentralon.
Only one of the four scrubber trains is used exclusively for
SOj control. The others remove about half of the S02 from
processed flue gas.
The FCD system consists of four modules of wet venturi-
type scrubbers. Three of the trains are single-stage
venturl scrubbers originally Intended for participate
removal. The fourth train Is a dual-stage venturl
scrubber -absorber and Is the prototype for determining
the feasibility of two-stage scrubbing for compliance
with SO: emission limits.
Parameter
Power Rating
Gross
Net Without FGD
Net With FGD
Average Capacity Factor
Sulfur Content
Ash Content
Heating Value
Removal Efficiency
Mech. Coll. ESP
FGD Systems
TOTAL
Composition
Calcium Oxide
Other
Stolchlometry
Removal Efficiency
Module 1
Module 2, 3 I 4
System Vendor
Type
Start-up Date
Prescrubber Type
Module Sice
Value
413 hV
397 Mf
373 Mf
66 Percent (1976)
2.15 Percent
18.2 Percent
11,350 Btu/lb
80.00 Percent
95.00 Percent
99.00 Percent
95.0 Percent
5.0 Percent
1.3
90 Percent
50 Percent
Chemlco
Retrofit
7/73
Variable-Throat Venturi
547,000 acfm 9 340°F
7. Demiater
8. Fan
The dnmlsters are an Integral part of the Chemlco venturl
scrubbers. The gas flown down through the venturl and back
up through the demistera. The denlsters are chevron-type
of fiberglass construction.
There is a booster f.in downstream of each of the pre-
scrubbers. The fans are equipped with fresh water
sprays to remove any accumulation of solids from scrubber
carryover.
Demlster Wash
System Pressure Drop
Internal Automatic Spray
-------
Ite
TABLE D-3. (Continued)
Description
Parameter
Value
9. Reheater
10. Sludge Disposal
11. Water Makeup
A 316-C stainless steel section of the duct
the stack Is equipped with a direct oil-fired rcheater
unit that can raise stack gas temperatures as much as
30*F. Normal reheat Is about 20*F.
The waste sludge Is stabilized by the addition of 200
pounds of calcllox per ton of dry solids In the sludge.
The fixed sludge Is transported to experimental plastic-
lined ponds located about one mile from the station,
where the material solidifies.
Both fresh water and recycle clarlfler overflow are used
In the system. The system operates
Flue Gas Temperature
Inlet 110-120*F
Outlet 1*0*F
Pond/Landfill
Fresh Water Makeup 635 gpm
-------
In the case of the two-stage S02 absorber train, gas leaving the ID fan
goes to a second absorber which is identical in size and mechanical design to
the first stage venturi scrubber. The primary difference between the first
and second stage scrubbers is that the second stage absorber is equipped with
lime slurry injection nozzles. This results in removal of 90 percent of the
SO2 which compares to 50 percent for the single stage trains.
Desulfurization flue gas leaves the second stage scrubber through a
spray washed demister. The gas is then reheated and exhausted to the atmos-
phere through the stack.
Lime for the FGD system is fed from a storage silo to a lime slaker
where it is mixed with fresh water to form calcium hydroxide. The slaked
lime then overflows to a transfer tank where makeup water is added until a
15 wt. percent solids slurry is produced.
Scrubbing liquor from the absorbers is withdrawn from a sump in the
bottom of each absorber and circulated by two recycle pumps. Some of this
recycle liquor is bled to the thickeners. Makeup liquor for the second
stage is drawn from the slaked lime transfer tank while makeup water for the
first stage scrubbers is bled from the second stage venturi recirculation
loop.
The purge streams from the absorber and the four scrubbers enter a
trough which feeds two 75 foot diameter thickeners. The overflow from these
thickeners is pumped to a makeup return line which recirculates clarified
liquor to the scrubber.
Undeflow from each thickener is pumped to one of three clay-lined
sludge holding ponds. However, before the sludge enters the holding ponds,
it is treated with a stabilizing agent. This promotes settling and curing
of the sludge in the pond. Finally, the cured sludge is excavated from the
pond and trucked to an off site disposal area.
208
-------
D.4 LA CYGNE GENERATING STATION
The LaCygne Power Generating Station of the Kansas City Power and Light
Company is located about 55 miles south of Kansas City. This station has a
single 874 MW, wet-bottom, coal-fired boiler fitted with an FGD system.
The boiler was first fired in December, 1972 and placed in commercial service
on June 1, 1973. The boiler is a base-load unit with an average capacity
factor of 23 percent (1974). Both the boiler and the FGD system are Babcock
and Wilcox design.
The FGD system installed at the LaCygne Station is a limestone slurry
scrubbing process. The system consists of seven identical scrubber modules,
limestone grinding and storage facilities, and a pond for disposal of unstab-
ilized limestone sludge. Figure D-4 is a schematic for the FGD system and
Table D-4 details the operating characteristics of the LaCygne boiler-
scrubber system.
The LaCygne Station has no auxiliary particulate control equipment.
The FGD system serves as the only means of particulate control and there is
no provision to bypass the system when it is out of service.
Limestone for the scrubbing system is obtained from a nearby quarry and
ground on site. A 60,000 ton supply is maintained near the coal storage
area. This limestone is transported intermittently to two wet ball mills by
the coal conveyor system. Limestone slurry leaves the mills and is stored
in one of two slurry supply tanks.
Each FGD module is comprised of a venturi scrubber in series with a
sieve tray absorption tower. The venturi removes most of the particulates
from the entering flue gas while the absorber removes most of the S02 . Each
module is capable of processing 394,300 acfm or about one seventh of the
total flue gas flow from the boiler.
209
-------
NJ
I-1
O
Figure D-4. La Cygne FGD System.
-------
TABLE D-4. OPERATING CHARACTERISTICS OF THE LA CYGNE BOILER-SCRUBBER SYSTEM
Item
Description
Parameter
Value
1. Boiler
2. Fuel
3. Participate Control
4. Absorbent Preparation
The LaCjrgne Power Generating Station has a single coal-fired
boiler Integrated vlth an FGD system. Both are of Babcock
and Wllcox design and construction. The boiler is a wet-
bo tt OB cyclone-fired unit which began commercial operation
on 6/1/73.
Low-grade, high-sulfur, sub-bituminous coal.
The FGD system Is the participate control device for the La Cygne
boiler. The venturl scrubber which precedes each of the seven
absorbers removes most of the partlculates fron the flue gas.
Limestone slurry absorbs S02 fro* the flue gas. The 1law-
stone Billing facilities consist of two wet ball Bills rated
at 108 ton/hr and two limestone holding tanks.
Power Rating
Gross
Ret Without FGD
Net With FGD
Average Capacity Factor
Sulfur Content
Ash Content
Beating Value
Removal Efficiency
Composition
Silicates
Calclun Carbonate
Magnesium Carbonate
Stoichlometry
874 HW
844 HW
820 HW
23 Percent (1974)
5.4 Percent
24.4 Percent
9420 Btu/lb
97 to 99 Percent
5-7 Percent
85-93 Percent
2.5 Percent
1.7
ts»
5. S0} Control
6. FGD System
7. Demlster
8. Pan
9. Reheater
10. Sludge Disposal
11. Make-up Water
The FGD system Is used to control SO: emissions.
The FGD system consists of seven identical modules, each
capable of processing approximately one-seventh of the
maximum flue gas flow from the boiler. The FCD modules
are comprised of a venturl prescrubber In series with s
two-stage sieve tray absorber.
A single stage Chevron type demlster Is located above
a third sieve tray In each absorber. Two of the modules
have a second demlster. The demlsters are washed continuously
from below and Intermittently from above. Demlsters are
constructed of fiberglass.
There are 6 ID fans located between the reheatera and the
stack. The suction side of these fans draws gas from a
common header connecting sll seven FCD modules.
Flue gas exiting the absorber Is rehested by heat exchange
with steam colls. This is supplemented by Injection of
hot air Into the flue gas stream.
Limestone slurry Is removed continously from the sbsorber
reclrculation tank and pumped directly to the sludge pond.
This slurry Is about 10 wt. percent solid and no treat-
ment Is used.
La Cygne operates si s closed-loop system. Fresh wster
Is added to make up for evaporative losaes and water
retained In the sludge.
Removal Efficiency
System Vendor
Type
Start-up Date
Prescrubber Type
Hodule Size
Demlster Wash
Top
Bottom
System Pressure Drop
Flue Gss Temperature
Inlet
Outlet
70-83 Percent
Babcock and Wllcox
Hew
6/1/73
Variable Throat Venturl
394,300 Acfm 9 285°F
2100 gpm Pond Supernatant/
1 mln. every 8 hr.
130 gpa Pond Supernatant/
Continuous
21-24 in. H20
121*F
175*F
Pond/Landfill
Requirements 400 Acre - Ft/yr
Make-up Rate
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Hot flue gas flows from the boiler and enters a venturi where it is
contacted with limestone slurry which is injected through nozzles in the
walls of the vessel. The gas and entrained slurry flow downward through the
venturi throat where the particulates impinge on the slurry droplets.
After passing through the venturi, the flue gas enters a sump where a
reduction in flue gas velocity causes entrained slurry droplets to fall from
suspension. The gas then flows upward through the S02 absorption tower and
passes through two perforated trays. The trays, which are wetted with lime-
stone slurry sprays, provide an extended surface for absorption of S02 by
the circulated slurry.
The scrubbed gas then passes through a third sieve tray which collects
slurry carryover and reduces the load on the demister. Each absorption
tower is fitted with a 10 inch high "Z" shape demister. and two of the seven
modules incorporate a second stage demister. As flue gas passes through the
demister, fine mist droplets coalesce on the surface of the demister vanes
and drip back into the tower. The demisters are washed by underspray and
overspray manifolds. Supernatant from the sludge disposal pond is used for
wash water. Each demister is washed continuously with 140 gpm of underspray
while the overspray operates intermittently at 2100 gpm for 1 minute during
each 8 hour period.
Flue gas exits the demisters and enters the reheater where the tempera-
ture is raised from 120°F to 175°F. Heat exchange with high pressure steam
is the primary mechanism for reheat, however, this is supplemented by hot
air injection on six modules.
Spent limestone slurry flows from the venturi/absorber sump to the
recirculation tank. Fresh limestone feed is added to the recirculation tank
and slurry is recycled to the absorbers. In addition, a purge stream of 10
wt. percent solids is continuously withdrawn from the recirculation tank and
212
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pumped directly to the sludge pond. Pond overflow water is recycled to the
FGD system, thus providing closed loop operation.
D.5 GREEN RIVER GENERATING STATION
The Green River Power Generating Station of the Kentucky Utilities
Company is located on the Green River near Central City, Kentucky. The
station which is operated as a peak load unit, consists of four boilers, two
generating units and an FGD system. The FGD system has been retrofitted on
boilers 1, 2 and 3 which have a combined generating capacity of 64 MW.
The Green River FGD system is a lime slurry scrubbing process. The
system was designed by American Air Filter Company and it began operation in
September, 1975. This FGD system consists of one scrubber, lime storage and
slaking facilities, and a sludge disposal pond. Figure D-5 is a schematic of
the FGD system and Table D-5 details the operating characteristics of the
Green River boiler-scrubber system.
As illustrated in Figure D-5, flue gas flows from the boilers through a
forced draft fan and then enters the scrubber module. The module is designed
to process 360,000 acfm of flue gas. It consists of a venturi prescrubber
in series with a mobile bed absorber.
The prescrubber removes most of the particulates and some S02 from the
gas stream. After passing through the prescrubber, flue gas enters the
bottom of the absorber and flows upward through the mobile bed contactor.
This mobile bed consists of ten sections with overhead lime slurry sprays.
As flue gas passes through the mobile bed, SOi is absorbed by the recirculat-
ing slurry and subsequently reacts with lime to form calcium sulfite.
Spent slurry exits the scrubber and goes to a reactant tank which is
divided into three sections. The slurry enters the return section (Figure
D-5) where makeup water and fresh lime slurry are added. The second and
third sections of the reactant tank provide sufficient retention time for
213
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Flue C«.
10
Fun
-?
Reryclt 1
Punr.il I
Q-
-M«k*-Up Weter
Sump
1
Reictmt
Tank
1
I
1
f ^ , , ..froM fond
^ £!=• -Mulce-Up Water
fe
•*• Bleed to Pond
Hike-Up Huter
Mm* Storage
'Screw Feeder
Hold Tank
SluVer
Figure D-5. Green River FGD System.
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TABLE D-5. OPERATING CHARACTERISTICS OF THE GREEN RIVER BOILER-SCRUBBER SYSTEM
Item
DescrlptIon
Parameter
Value
N>
H
1. Boiler
2. Fuel
3. Partlculate Control
4. Absorbent/Preparation
5. SO2 Control
6. FGD Systeal
The Green River Station has four coal-fired boilers,
three of which have been retrofitted with.an FGD system.
Green River Is a peak load station vhlch normally
operates five days a week.
A high-sulfur, western Kentucky coal Is burned In the
boilers.
The FCD syatc
collectors.
la used In conjunction with mechanical
Line slurry Is used to absorb SOj from the flue gas.
Pebble lime Is purchased and stored In, a 500-ton capacity
bin. Line Is slaked In an agitated tank to produce a 20
percent solids slurry.
The FGD system controls SO2 emissions In order to Beet
air quality regulations.
The FGD system consists of a single Module capable of
treating all of the flue gas from boilers 1, 2, and 3.
The Module consists of a venturl prescrubber In series
with a mobile-bed absorber.
Power RatIng
Net with FCD
Average Capacity Factor
Sulfur Content
Ash Content
Heating Value
Removal Efficiency
Mechanical Collectors
FCD System
Composition
Stolchlometry
Removal Efficiency
System Vendor
Type
Start-Up Date
Prescrubber Type
Module Sice
64
3.8 Percent
99.7 Percent
80 Percent
American Air Filter Co.
Retrofit
9/75
Venturl
360,000 acfm 9 300°F
7. Demlster
A cyclone demlster Is used to remove entrained
from the flue gas stream leaving the absorber.
list
Demlster Wash
Top
8. Fan
9. Reheater
A forced draft booster fan Is located upstream of the
venturl prescrubber.
There Is no reheater on this system.
System Pressure Drop
10. Sludge Disposal
11. Water Makeup
Sludge is pumped to an unllned pond. Clear pond over- Pond Landfill
flow is returned from the pond to the reactant tank. Requirements
Makeup water la added to the oystem to replace evaporative Makeup Rate
losses and water whJch la retained In the sludge.
-------
completion of the sulfite/sulfate precipitation reactions. Slurry from the
third section of the reaction tank is recycled to the venturi prescrubber
and the absorber.
Fresh slurry is prepared by feeding pebble lime into an agitated slaking
tank. Slurry is discharged from the slaker hold tank and then pumped to the
reactant tank.
A bleed stream is withdrawn from the reactant tank to remove sulfite/
sulfate solids and collected fly ash. This bleed is pumped to the disposal
pond where the solids settle. Pond overflow is recycled to the FGD system
thus providing closed loop operation.
D.6 PADDY'S RUN GENERATING STATION
The Paddy's Run Power Generating Station of the Louisville Gas and
Electric Company is located on the Ohio River in Rubbertown, Kentucky. Unit
No. 6 at the Paddy's Run Station has been retrofitted with an FGD system.
This unit is a 70 MW, dry-bottom, pulverized-coal-fired boiler designed
and installed by Foster-Wheeler in 1951. It is used only during periods of
peak load and the average capacity factor is approximately 5 percent.
The FGD system, which uses a lime slurry to absorb S02, was designed
and manufactured by Combustion Engineering, Inc. and placed in service in
April, 1973. The system consists of two identical absorbers, lime slurrying
facilities, and sludge dewatering equipment. The system operates closed-
loop with respect to process water. Fresh water is used to replace evapora-
tive losses and water retained in the sludge. Figure D-6 is a schematic
of the Paddy's Run FGD system and Table D-6 illustrates the operating
characteristics of the boiler-scrubber system.
Flue gas from Unit No. 6 flows through a Research-Cottrell electrostatic
precipitator prior to entering the FGD system. The ESP operates with an
216
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Natural Gas
Natural Gas
Flue Gas
Carbide Lime Slurry
Additive Tank!
To Dispooal
Figure D-6. Paddy's Run FGD System.
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TABLE D-6. OPERATING CHARACTERISTICS OF THE PADDY'S RUN BOILER-SCRUBBER SYSTEM
00
Item Description
1. Boiler Unit No. 6 of the Paddy's Run Power Generating Station is
a dry-bottom, pulverized-coal-f ired boiler. The boiler
vas Manufactured by Foster Wheeler and installed in 1951.
2- Fuel High sulfur coal.
3. Particulate Control A Research-Cottrell ESP provides primary particulate con-
trol for Unit No. 6
4. Absorbent/Absorbent A carbide line Blurry is used to absorb SOj from the flue
Preparation gas. This Hme ia purchased as a sludge by-product from
an actylene manufacturing plant. The limp sludge Is nixed
with water in an agitated slurry tank.
5. S0? Control The FGD ays tea is used to control SO? emissions.
6. FGD Systen The FGD system consists of two identical modules each de-
signed to process 50 percent of the maximum flue gas flow
from Unit No. 6. The nodules are two-stage, marble bed
absorbers.
7. Demister A two-stage, chevron-type demist er IB located 4 feet above
the upper narble bed In each absorber. The denisters are
Parameter
Power Ral Ing
Gross
Net Without FGD
Net With FCD
Average Capacity Factor
Sulfur Content
Ash rontent
Heating Value
Removal f.fflciency
Electrostatic Preclp.
. FGD Systems
TOTAL
Composition
Silica
Calcium Hydroxide
Calcium Carbonate
Magnesium Oxide
Other
Stolchiometry
Removal Efficiency
System Vendor
Type
Start-up Date
Presc rubber Type
Nodule Size.
Denister Wash
Top & Bo t ton
Value
70 MW
65 >IW
63 MW
5. Percent (1974)
3.71 Percent
13.8 Pencent
12,400 Btn/lb.
99.1 Percent
85.90 Percent
99.9 Percent
1 .5 Percent
92.5 Percent
1.9 Percent
0.1 Percent
4.0 Percent
1.0
85 - 90 Percent
Combustion Engineering
Retrofit
4/73
None
1 /5,ooo ACFN
-------
efficiency of 99.1 percent and provides primary control of particulate
emissions from the boiler.
Flue gas flows into the FGD system and is split between the two modules,
each capable of processing 175,000 acfm. Flue gas enters the scrubber module
near the base where it contacts sprays which provide a constant supply of
slurry to the underside of the marble beds. This slurry also serves to cool
the flue gas adiabatically to its saturation temperature before it enters
the marble bed. The wetted flue gas rises through the bed and carries the
slurry with it. The vigorous action of the marbles mixes the flue gas and
slurry to form a "turbulent layer" above the marble bed. The turbulent
layer provides the necessary surface area to effect the required degree of
S02 absorption and particulate removal. After emerging from the second
marble bed, the clean flue gas passes through a two-stage chevron mist
eliminator where entrained water droplets are agglomerated and removed.
The flue gas then passes through a gas-fired reheater, through a booster fan,
and out the stack.
Spent slurry is withdrawn continuously from the absorbers and sent to a
reaction tank where fresh lime is added and calcium sulfite/sulfate precipi-
tate. Slurry from the reaction tank is returned to the absorber while a
stream is bled to a thickener where the sulfite/sulfate solids are concen-
trated.
The underflow from the thickener is sent to a rotary vacuum filter.
Filter cake is trucked to an off-site landfill area. Vacuum filtrate is
recycled to the thickener, and pumped back to the reaction tank to close the
liquid effluent loop.
Lime for the scrubber is obtained as sludge which is known as "carbide
lime". It is generated as a waste by-product from a nearby acetylene
manufacturing operation.
219
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TECHNICAL REPORT DATA .
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-600/7-79-113
2.
3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
Comparison of the Availability and Reliability of
Equipment In the Electric Utility Industry
S. REPORT DATE
Mav 1979
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
J.C. Dicker man, R.T.Coleman, J. M. Burke, and
C.C.Thomas
8. PERFORMING ORGANIZATION REPORT NO.
10. PROGRAM ELEMENT NO.
EHE624
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Radian Corporation
P.O. Box 9948
Austin, Texas 78766
11. CONTRACT/GRANT NO.
68-02-2608, Task 48
12. SPONSORING AGENCY NAME AND ADDRESS
EPA, Office of Research and Development
Industrial Environmental Research Laboratory
Research Triangle Park, NC 27711
13. TYPE OF REPORT AND PERIOD COVERED
Task Final; 7/78 - 3/79
14. SPONSORING AGENCY CODE
EPA/600/13
is. SUPPLEMENTARY NOTES JERL-RTP project officer is John E. Williams, Mail Drop 61
919/541-2483.
16. ABSTRACT
The report gives results of a study to compare the reliability/availability
of flue gas desulfurization (FGD) systems with equipment commonly used in the elec-
tric utility industry. Because many parameters used in reporting performance data
for these systems have different definitions from one data reporting system to ano-
ther, a direct comparison could not be made. However, a comparison model was
developed--incorporating such factors as reliability, development status, and
repair effort—to produce a single statistic that could be used to directly compare
dissimilar pieces of equipment or systems. Study results indicate that a statisti-
cally meaningful comparison of the re liability/availability of utility FGD systems
cannot now be made, primarily because of the small amount of FGD system perfor-
mance data currently available. A meaningful comparison can be made only after
more FGD systems are installed and more complete performance records become
available.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS
COS AT I Field/Group
Pollution
Flue Gases
Desulfurization
Electric Utilities
Reliability
Availability
Mathematical
Models
Pollution Control
Stationary Sources
13B
21B
07A,07D
14D
12A
13. DISTRIBUTION STATEMENT
Unlimited
19. SECURITY CLASS (ThisReport)
Unclassified
21. NO, OF PAGES
227
20. SECURITY CLASS (Thispage)
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
220
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