&EPA
United States
Environmental Protection
Agency
Environmental Research
Laboratory
Corvallis OR 97330
Research and Development
EPA-600/3-79-072
July 1979
Evaluation of
European
Rivers for Power
Plant Cooling
A Polish Research Project
-------
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 ECOLOGICAL RESEARCH series. This series
describes research on the effects of pollution on humans, plant and animal spe-
cies, and materials. Problems are assessed for their long- and short-term influ-
ences. Investigations include formation, transport, and pathway studies to deter-
mine the fate of pollutants and their effects. This work provides the technical basis
for setting standards to minimize undesirable changes in living organisms in the
aquatic, terrestrial, and atmospheric environments.
Th>s document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
-------
EPA-600/3-79-072
July 1979
EVALUATION OF EUROPEAN RIVERS
FOR POWER PLANT COOLING
A POLISH RESEARCH PROJECT
by
Dr. Eng. Mieczyslaw Gadkowski
Institute for Meteorology and Water Management
61 Podlesna str.
01-673 Warsaw
POLAND
PL 480 Project No. PR-5-532-14
U.S. Project Officer
Bruce A. Tichenor
Criteria and Assessment Branch
Environmental Research Laboratory
Con/all is, Oregon 97330
CORVALLIS ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D.C. 20460
-------
DISCLAIMER
This report has been reviewed by the Corvallis Environmental Research
Laboratory, U.S. Environmental Protection Agency, and approved for publica-
tion. Approval does not signify that the contents necessarily reflect the
views and policies of the U.S. Environmental Protection Agency, nor does
mention of trade names or commercial products constitute endorsement or recom-
mendation for use.
-------
FOREWORD
Effective regulatory and enforcement actions by the Environmental Pro-
tection Agency would be virtually impossible without sound scientific data on
pollutants and their impact on environmental stability and human health.
Responsibility for building this data base has been assigned to EPA's Office
of Research and Development and its 15 major field installations, one of which
is the Con/all is Environmental Research Laboratory (CERL).
The primary mission of the Corvallis Laboratory is research on the ef-
fects of environmental pollutants on terrestrial, freshwater, and marine eco-
systems; the behavior, effects and control of pollutants in lake systems; and
the development of predictive models on the movement of pollutants in the bio-
sphere.
This report presents the results of a cooperative study by the Institute
of Meteorology and Water Management of Poland under the Special Foreign Cur-
rency Program, PL-480.
The objective of this study was to determine the optimal mix of cooling
system alternatives for stream electric generating stations to be located on
Polish rivers.
James C. McCarty
Acting Director, CERL
ill
-------
ABSTRACT
The report describes analytical, laboratory, and field research conducted
to optimize the use of rivers, specifically in Poland, for once-through cool-
ing of steam electric power plants. Variations in river flow over several
years are analyzed to determine statistically reliable low flows for various
parts of the year. Variations in river temperatures are also analyzed to
provide a statistically valid picture of annual temperatures in streams.
Maximum discharge and receiving water temperatures, based on biological cri-
teria, are coupled with natural flow and temperature variations to determine
acceptable flow/temperature regimes for streams over an annual cycle. Con-
trollable variables, such as repair schedules, reserve capacity, power plant
site, hybrid cooling system size and operation, and low flow augmentation via
reservoirs, are evaluated as mechanisms to modify electric power generation
over an annual cycle. The acceptable temperature/flow regimes in streams are
then compared to various power system configurations and schedules to optimize
the annual generation of electric power. The following conclusions are reach-
ed, relative to Polish conditions:
the installed capacity of open cycle cooling systems can be in-
creased by about 25% without installing supplemental cooling.
for increases greater than 25%, mechanical draft cooling towers and
double pass condensers operated in a hybrid, open cycle is the most
economical solution.
low flow augmentation for power plant cooling via upstream reser-
voirs is economical only when used in a comprehensive water manage-
ment plan.
This report was submitted in fulfillment of PL 480 Project No. PR-5-532-14 by
the Institute of Meterology and Water Management, Warsaw, Poland under an
agreement with the U.S. Environmental Portection Agency. This report covers a
period from February, 1974 to December, 1977 and the report was completed as
of May, 1978.
-------
CONTENTS
Page
Foreword iii
Abstract iv
List of Figures vii
List of Tables viii
Acknowledgements x
Introduction 1
1. Hydrological Basis 1
1.1. Introduction 1
1.2. Reliable Flows 1
1.3. Magnitude and Distribution of Minimum Reliable Flows 8
1.3.1. Minimum Reliable Flows in Polish Rivers 8
1.3.2. Magnitude and Distribution of Low Flows in
European Rivers 9
1.4. Flow Shortages 15
1.5. Maximum Reliable Water Temperatures 15
2. Acceptable Temperature Increases in Free-flowing Rivers 18
2.1. Variability of River Water Temperature 18
2.2. Review of Temperature Increases Caused by Existing
Steam Power Plants 20
2.2.1. Polish Steam Power Plants 20
2.2.2. French Power Plants 26
2.2.3. Other European Countries 26
2.3. Legal Limitations of Temperature for Open Cycle
Cooling of Steam Power Plants 28
2.4. Impact of Heated Water on the Oxygen Balance in
Receiving Water 33
2.5. Impact of Heated Waters on Fishes 33
2.6. Proposals for Permissible Temperatures 33
3. Variability of Steam Power Plant Load 37
3.1. Introduction 37
3.2. Daily Load Changes 37
3.3. Steam Power Plant Operating Time 39
3.4. Monthly Coefficients of Installed Capacity Utilization .... 44
3.4.1. Statistical Analysis of Production Changes 44
3.4.2. Repairs Schedule 44
3.4.3. Cosine Model 48
3.4.3.1. Analysis of Calculation Method 48
3.4.3.2. Amplitude of Yearly Changes of g.
Coefficients 52
-------
3.4.3.3. Designation of Correction Coefficient, f-- - 52
3.4.3.4. Designation of Af. Coefficient 53
3.4.3.5. Analysis Summary ? 53
3.4.4. BETA Distribution Model 55
3.5. Summary of Analysis of Monthly Installed Capacity
Utilization Coefficients 58
4. Power Plant Capacity and its Relation to Temperature
Increases Downstream from the Discharge 61
4.1. Power Plant Capacity 61
4.2. Mixed Temperature Increases Downstream From Power Plants ... 62
4.3. Discharge Design 64
4.3.1. Field Investigations 64
4.3.2. Model Investigations 69
5. Combined Cooling Systems and Flow Augmentation 76
5.1. Review of Combined Cooling Systems and Flow Augmentation
for Power Plants 76
5.2. Assumptions Used in Analyses 78
5.3. Determination of Hybrid Circuit Capacities 78
5.4. Economic Aspects of Combined Cooling Circuits 82
5.5. Increase of Open Cycle Cooling Possibilities by
Augmentation of Low Flows 83
5.6. Cooling in Discharge Channels and Precooling Reservoirs ... 85
5.7. Utilization of Mechanical Draft Cooling Towers 93
6. Summary 94
7. Conclusions 97
References 98
VI
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LIST OF FIGURES
Page
Fig. 1.1. Area Under Investigation 5
Fig. 1.2. Distribution of K.,no, Coefficients on Lower and
Middle Vistula and'oler 13
Fig. 1.3. Distribution of K.,,,^ Coefficients on Upper Vistula
and Upper Oder and on San, Warta and Narew Rivers 14
Fig. 1.4. Distribution of K.im; Coefficients on Large and
Medium Rivers . ? 16
Fig. 2.1. Temperature Distribution in the Thermal Plume Below
the Skawina Power Plant, 1963 (Temp. Measurement
at 7:00, 12:00 and 18:00) 21
Fig. 2.2. Daily Temperatures in the Vistula River Below and
Above the Skawina Power Plant in 1963 22
Fig. 2.3. Daily Temperature Changes in the Cooling System in
the Patnow Power Plant 24
Fig. 2.4. Temperatures in Cooling System of the Konin and
Patnow Power Plants, Summer 1975 25
Fig. 2.5. Changes in Oxygen Content After Passing Through the
Cooling Systems of Steam Power Plants 34
Fig. 3.1. Daily Load in Power Plant of Yearly Operation Time
T = 7000 Hours 40
Fig. 3.2. Average Real Coefficients of Installed Capacity
Utilization in Polish Multiunit Steam Power Plants,
1967 - 1978 47
Fig. 3.3. Comparison of Real and Calculated Coefficients of
installed Capacity Utilization at Polish Power
Plants 60
Fig. 4.1. Maximum Temperature Decrease in the Discharge Zone
Below the Kozienice and Ostroleka Power Plants 70
Fig. 4.2. Maximum Temperature Decrease at a Longer Distance
Below the Discharge From the Kozienice Power Plant 71
Fig. 4.3. Average Maximum Temperature Drop in the Thermal
Plume Below the Kozienice Power Plant 72
Fig. 4.4. Scheme of Model 73
Fig. 4.5. Arrangement of Discharge Jet Axes With Regard to
Changes of Outlet Angle 6 for b/B = 0.5 74
Fig. 5.1. French Power Plant Cooling Systems 77
Fig. 5.2. Heat Losses in Precooling Reservoirs 87
Fig. 5.3. Measurement Points in the Discharge Channel of the ,
Patnow Power Plant 89
Fig. 5.4. Water Cooling in the Discharge Channel of the Patnow
Power Plant - Surveys in 1975 90
Fig. 5.5. Indicator of Water Cooling in the Discharge Channel
of the Patnow Power Plant, °C/1 km°C 92
vii
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LIST OF TABLES
Page
Table 1.1. Rivers Under Investigation 3
Table 1.2. Comparison of Open Cooling System Flow
Requirements and River Flows for Some Steam
Power Plants 7
Table 1.3. Distribution of K.,ny Coefficients for European
n • ' • U/O 1 f\
Rivers 10
Table 1.4. Flow Shortages for the Summer With Different
Control Ratios, s, for p = 90% 17
Table 2.1. Monthly Temperature Differences Between the Upper
Rhone and Arve Rivers 19
Table 2.2. Monthly Average Temperature Increases in the
Vistula Downstream From the Skawina Power Plant, °C .... 23
Table 2.3. Monthly Average Maximum Temperature Increases at
French Power Plants, °C 27
Table 2.4. Thermal Standards in Some European Countries 29
Table 2.5. Permissible Temperature Decreases at Polish
Power Plants 30
Table 2.6. A, B, and a at Selected Locations 35
Table 2.7. The Lethal Temperatures for Cyprinides 36
Table 3.1. Daily Load Changes in Large Polish Steam Power
Plants With Open Cooling Systems (%) 38
Table 3.2. Frequency of Maximum Daily Load in a Power Plant
with T = 7000 hours operation time 41
Table 3.3. Time of Full Load Installed Capacity in Some
Countries (Hours) 42
Table 3.4. Expected Time of Full Load Installed Capacity for
Nuclear Power Plants in Some Countries (Hours) 43
Table 3.5. Time of Full Load Capacity in Polish Power Plants,
Units of 120 and 200 MW (Hours) 45
Table 3.6. Expected Time of Full Load Installed Capacity
for Polish Power Plants in 1980, 1985, and 1990 (Hours) . . 45
Table 3.7. Installed Capacity Utilization Coefficients for Large
Power Plants, 1967-1973 (%) 46
Table 3.8. Expected Installed Capacity Utilization Coefficients
for Steam Power Plants (%) 48
Table 3.9. Monthly Indicators of Capacity Decreases Due
to Repairs (%) 49
Table 3.10. Values of Af 54
Table 3.11. Monthly Average Installed Utilization Coefficients,
g, Various Operating Times, T/h/year 56
Table 3.12. Comparison of Installed Capacity Utilization Monthly
Coefficients Obtained by Different Methods of
Computation 59
viii
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Table 4.1. Calculation of Installed Capacity in Open Cycle
Cooling in Polish Rivers 63
Table 4.2. Comparison of Calculated vs. Measured Temperature
Increments in The Vistula River Downstream from
the Skawina Power Plant 65
Table 4.3. Field Investigation Results in the Vistula River
Downstream From the Kozienice Power Plant ......... 66
Table 4.4. Field Investigation Results in the Vistula River
1000 m From the Discharge of the Kozienice Power Plant ... 67
Table 5.1. Coefficient of Open Cooling System Variation, m 80
Table 5.2. Dependence of Hybrid Cooling Systems Operation Time
on Hybrid Circuits Size (in % of Open Cooling System
size) 81
Table 5.3. Cooling System Parameters in Relation to Rate of
Flow Augmentation in the Pulawy Cross-Section 84
Table 5.4. Economics of Cooling System Size vis-a-vis Flow
Augmentation in the Pulawy Cross-Section
IX
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ACKNOWLEDGMENTS
Grateful acknowledgments are made for the assistance of Dr. Bruce
Tichenor and Mr. Howard Zar, representatives of the U.S. Environmental Protec-
tion Agency. The author acknowledges the following Polish specialists and
colleagues for their consultation and assistance in the research and prepara-
tion of this report:
Dr. Eng. Wojciech Poplawski, Eng. Roman Junko and members of the
Water Physics Department for their assistance in the elaboration of
the field investigations.
M.Sc. Eng. Andrzej Dobrowolski and members of the Hydraulic Depart-
ment for the study and elaboration of the laboratory thermal inves-
tigation.
Dr. Eng. Andrzej Filipkowski and Dr. Ryszard Krasnodebski for the
mathematical analysis.
Assistant Professor Lidia Horoszewicz for organizing and leading the
specialized team for elaboration of the impact of heated waters on
fish.
M.Sc. Eng. Waclaw Zarzycki for organizing and leading the special-
ized team for the elaboration of changes of power plant load.
M.Sc. Raimund Wisniewski for consultation on impact of heated water
on the biology of the water body.
The author's colleagues: M.Sc. Eng. Hanna Spoz-Dragan, M.Sc. Eng.
Ewa Kurhanowicz, M.Sc. Julia Surowiec, tech. Irena Piaszczynska,
Prof. Dr. Eng. Mieczyslaw Zajbert, Asst. Professor Antoni
Symonowicz, M.Sc. Franciszek Jastrzebski, M.Sc. Eng. Stanislaw
Wiecek, for their comments and assistance in the preparation of this
report.
-------
INTRODUCTION
This report describes research conducted to establish rules for esti-
mating the optimum installed capacity of power plants with once-through cool-
ing systems and with hybrid cooling systems. Hybrid" systems can use cooling
towers, cooling ponds and spray devices, intermittently or continuously to
reduce the waste heat discharge to acceptable levels.
The factors used in determining the optimum installed capacity of a power
plant are:
representative low flows,
acceptable temperature increases in the river below the discharge,
power plant load.
-------
1. Hydrological Basis
1.1. Introduction
This report deals with the possibilities of supplying steam electric
power plants with cooling water from free flowing rivers (i.e., without arti-
ficial flow control). In the case of rivers used as a cooling water source,
the probability of occurrence of low flows has a practical use because it
enables proper estimation of the cooling capabilities of the river.
This report gives flow characteristics for a number of European rivers
used for power plant cooling. The analyses are based on monthly low flows
over many years. The report also presents views on minimum reliable flows in
various countries for industrial needs, as well as for power plant cooling.
The investigations covered river basins which differed with respect to
their size and character; thus, small, medium, and large basins, as well as
mountain and lowland basins were investigated. Polish rivers have been stud-
ied in greater detail, since the basic data for their investigation were more
available.
To meet the objective of this study, analyses were conducted to determine
the following:
magnitude of low flows and their annual distribution,
magnitude and duration of the continuous low flows,
characteristics of monthly low flows.
A total of 42 cross-sections on 25 rivers from various river basins were
investigated. Data on the rivers and cross-sections investigated are given in
Table 1.1. and on the map (Figure 1.1) at a scale 1:12,000,000. Note that
Figure 1.1 uses the Polish spelling of some rivers.
Analyses were conducted using data from Polish laboratories and technical
references as well as data from other European countries.
1.2. Reliable Flows
Until recently, the required conditions commonly assumed for open cooling
system operation on rivers related the constant demand for cooling water to
the minimum flow with a definite probability of occurrence; generally between
95 and 98%.
In analyzing the problem of low flow rates, it should be pointed out that
such severe conditions for open cooling systems are not justified. The re-
-------
TABLE 1.1. RIVERS UNDER INVESIGATION
No.
1
1.
2.
3.
4
5.
6.
7.
8
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
26.
27.
28.
29.
River
2
Vistula
n
M
it
n
n
n
n
n
ti
San
Narew
Oder
n
n
M
n
M
Varta
n
Marie
Arda
Dnieper
n
Dniester
Neman
n
Daugave
n
Cross-
Section
3
Tyniec
Jagodniki
Szczucin
Sandomierz
Zawichost
Pulawy
Warsaw
Plock
Torun
Tczew
Radomysl
Ostroleka
Scinawa
Nowa Sol
Cigacice
Polecko
Slubice
Gozdowice
Gorzow Wlk
Poznan
Pazardzhik
Studen-
Kladenets
Kiev
Kremenchug
Zaleszczyki
Kaunas
Smalininkai
Dvinsk
Plavinskaja
GES
Area of Longterm
Basin Mean Annual
(km2) Flow (m3/s)
4
7525
12049
23885
31819
50685
57224
84823
169386
180780
194259
16823
21870
29615
37304
39913
47293
53580
109364
51893
25093
4136
3407
328000
383000
24600
45700
81200
64400
81500
5
90.7
134
246
287
419
450
560
909
972
1020
135
107
167
212
224
266
308
528
206
94.3
21.6
58.6
1360
1430
214
270
517
456
589
Years of
Record
6
1921-73
n
M
n
n
n
n
ii
n
n
n
n
n
n
n
ii
n
ii
n
n
n
11
n
n
n
M
II
II
II
Country
7
Poland
n
n
n
n
n
n
n
1!
II
II
II
II
II
II
II
II
II
II
II
Bul-
garia
n
USSR
n
n
M
n
n
n
continued ...
-------
Table 1.1 (cont.)
30.
Vltava
Modrany
26703
146
1941-70
Czecho-
slova-
kia
31. Vah
32. Danube
33.
34. Olt
35.
36.
37.
38.
39.
40.
41.
42.
Si ret
Bistrita
Seine
Garonne
Dordogne
Loire
Rhone
Rhine
Sala 10619
Budapest
Orsova 576000
Rimnieu
Vilcea 15292
Racaciuni 19539
Bicaz
Paris 43800
Mas D'Agenais 52000
Dome (Cenac) 8700
Mont-Jean 110000
Beacaire 95000
Bale 35925
150
2350
5490
124
100
40.
253
590
180
847
1705
1035
1954-69
1941-70
Hungary
Rumania
1927-65
1921-65
France
-------
33
o
m
X)
m
3
o
MEDITERRANEAN SEA
Scale 1:12000000
-------
suits of these investigations show that there is a period within the annual
power plant operation cycle in which the water demand drops by about 25%.
Apart from that, minimum flows with a probability of occurrence p=95% and
p=98% are infrequent and of short duration. Thus, they do not represent the
normal flow conditions at the power plant intake. This aspect of minimum
flows is also pointed out by some hydrologists (Laszloffy 1960, Zielinska
1964, Remenieras 1972). Data from several steam power plants confirm this
thesis, since the total demand for water exceeds the minimum flows in rivers
quite frequently (Table 1.2.).
Power plant operating experiences were used to work out the new methods
for low flows estimation and their classification concerning steam power
plants cooling cycles water demand. In 1966, the Polish Union of Power En-
gineering assumed that flows with the probability of occurrence p=95% in
December would ensure guaranteed capacity of the plant; while in November,
January and February it is possible to reduce the power of the plant by 10%.
Reduced load requirements during the summer months provide reduced flow re-
quirements in the summer.
One of the first methods of calculating minimum flows for open cycle
cooling systems was presented in 1968 (Gadkowski). In this method, the year
is divided into two periods: winter, November through April; and summer, May
through October. Analyses showed that low flows in both periods are at the
same level. However in winter, under low water temperatures, it is necessary
to use recirculation (intake heating) which reduces intake demands. This
means that flow shortages for open cooling cycle operation usually occur only
in the summer.
To determine the minimum reliable flow, a 95% guaranteed water supply for
steam power plants is the practice in Poland. This means that hydro!ogical
conditions should safeguard the power plant operation through 95% of the year;
for the remaining 5% of the year (i.e., 18 days in the summer) flows may be
lower than the reliable value. This condition was related to a dry year with
a probability of occurrence, p=95%.
The rules of the minimum reliable flows in other European countries are
presented below:
In Romania (Zanavello 1964), low flow rates of 10 consecutive days with a
frequency of occurrence p=95% are recommended.
An interesting method for low flow evaluation was worked out in Hungary
where reliable flows lasting for 80% of August and 97.5% to 99.0% of September
were taken as reliable low flow rates. During other months, the reliable
flows are assumed to last for 100% of the time.
In West Germany, low flow rates of 20 consecutive days with a frequency
of occurrence once in 30 years are recommended. In the temperature calcula-
tions for the Neckar River in West Germany (Flinspach 1973), low flows occurr-
ing at least 10% of the time in June, July and August in the years 1951-1965
have been accepted as reliable flows.
-------
TABLE 1.2. COMPARISON OF OPEN COOLING SYSTEM FLOW REQUIREMENTS
AND LOW RIVER FLOWS FOR SOME STEAM POWER PLANTS.
Power Plant
Country
Vitry sur Seine
France
Monte reau
France
Lacq-Artix
France
Beautor
France
Blenod
France
God in
Czechoslovakia
Skawina
Poland
Neckar
West Germany
Power Plant
Capacity (MW)
1,000
750
375
375
1,000
200
550
900
Cooling Water
Flow (m3/s)
34
27
20
14.1
40
9
24
40
River
Seine
Seine
Gave du Pou
Oise
La Moselle
Morava
Vistula
Neckar
Low Flows
(rnVs)
29
25
13
15
27
7
19
4.3
5.52
8.54
13.8
20
Hydrological Character-
istic of Low Flows
Lowest monthly flow
Average yearly low flow
Absolute minimum
Average yearly low flow
Flow of 329 days
duration (Q32g)
Average yearly low flow
Low monthly flows in
Sept. and Oct. p=10%
Daily minimum in 1972
Flow of 364 days duration
Flow of 355 days duration
Lowest monthly flow
Average yearly low flow
Chesterfield
USA
1,212
44
James
14
Average yearly low flow
-------
In France, the Interdepartmental Mission (AFdB 1975), established to
evaluate low flows, has analyzed the following methods of classification of
minimum flows:
low consecutive flows of a duration of 10 and 30 days,
low monthly flows with a probability of occurrence, p=90%.
As a result of this classification, low monthly flows occurring once in 10
years were recommended as reliable to water management authorities.
In the United States, 7 day consecutive low flows with the probability of
occurrence p=90% are most often assumed as reliable flows. In some cases,
however, this rule is modified (e.g., in temperature computations regarding
steam power plants situated on the Ohio River, low flow rates of 30 consecu-
tive days with a frequency of occurrence once in 10 years were assumed as
reliable flows, Butz 1974).
On the basis of the above review of various opinions regarding reliable
flows for evaluating cooling system operation in the steam power plants, low
monthly flows with a probability of occurrence of p=90% are assumed as reli-
able flows in this report.
1.3 Magnitude and Distribution of Minimum Reliable Flows
1.3.1. Minimum Reliable Flows in Polish Rivers
As discussed in section 1.2. low monthly flows with a probability of
occurrence of p=90% are proposed as the base for hydrological analyses of open
and combined cooling cycles. Such flows are treated as minimum flows for the
evaluation of the effective power output for power plants with open cooling
systems. In addition, lower monthly flows with a probability of occurrence,
p=95%, are suggested as worst case conditions.
To standardize the results of the investigations carried out for differ-
ent types of rivers, coefficients previously suggested by Gadkowski, K.
(i.e., coefficients of flow distribution according to equations 1.1 and l.z°
have been used. This form of expression has recently become more and more
widely used (Bratranek 1966, Laszewski).
Q •
x
• or,
min 90
i 10% ~ ~7~~Q
„ _ Milin 95
Ki 5% --
where:
Q = mean annual flow of many years,
^min 90 = low monthly flow of the probability of occurrence, p=90%,
^min 95 = low monthly flow of the probability of occurrence, p=95%.
Coefficients of distribution, K. ,Qc£ for Polish and other European rivers are
given in Table 1.3 and Figures 1.2 ana 1.3.
8
-------
If the values of the coefficient, K. ,Q^, are analyzed for the Vistula
and Oder Rivers, each year may be divided irvto three periods:
from February to June - a favorable period for open cooling systems
of steam power plants due to high spring flows,
from November to February - a safe period for open cooling systems
of steam power plants with slightly increased flows,
from July to October - a critical period for open cooling systems of
steam power plants, i.e. a period of summer and autumn low flow
rates.
In the critical periods, special attention should be paid to months
characterized by minimum coefficients of distribution. All along the Vistula
they occur in September, but on the Oder they occur at different times in
various stretches of the river. In the upper stretches of the Oder, they
occur in October, in the middle stretches in September, and in the lower
reaches in August. However these differences are slight and if the Vistula
and Oder distribution coefficients are compared (see Figures 1.2 and 1.3), it
is seen that their values and distribution throughout the year are similar.
Slightly higher coefficients occur all along the Oder in November, December,
January and February, while in the summer and autumn months the coefficients
of distribution are similar for both rivers.
A comparison of individual stretches of the Vistula and Oder indicates a
displacement of the maximum spring flow in the lower stretch from March to
April in relation to the middle and upper stretch. All through the remaining
part of the year (in summer, autumn, and winter) the K. coefficient values of
the lower Vistula stretch are about 5% higher than ^ose of the upper and
middle stretches. In the Oder, this increase is even higher.
Considering the possibility of using these stretches for cooling, this
phenomenon should be pointed out as very favorable. The most suitable distri-
bution coefficients, from the point of view of cooling, appear in the lower
stretch of the Oder.
Among other rivers examined, the K. distribution coefficients are partic-
ularly interesting in the Varta River. In the lower stretch at the Gorzow
Wielkopolski cross-section, K. 1Qy coefficients remain at the same level (near
0.40) for five summer and autumn months and in winter they are about 0.50.
From the point of view of using open cooling systems, this cross-section is
the most suitable of the Polish rivers examined.
1.3.2. Magnitude and Distribution of Low Flows in European Rivers
In relation to their cooling capability, European rivers have been di-
vided into two groups - medium and large. Large rivers can provide cooling
water to open cycle power plants with capacities greater than l.OOOMW; medium
rivers provide cooling for open cycle plants with capacities up to l.OOOMW.
-------
River
Vistula
Vistula
Vistula
Vistula
Vistula
Vistula
Vistula
Vistula
Vistula
Vistula
San
Narew
Oder
Oder
Oder
TABLE 1.3.
Cross
Section
Tyniec
Jagodniki
Szczucin
Sandomierz
Zawichost
Pulawy
Warsaw
Plock
Torun
Tczew
Radomysl
Ostroleka
Scinawa
Nowa Sol
Cigacice
DISTRIBUTION OF Ki10
COEFFICIENT
FOR EUROPEAN RIVERS
Months
XI
0.29
0.32
0.30
0.33
0.33
0.36
0.38
0.38
0.42
0.43
0.24
0.49
0.35
0.42
0.40
XII
0.36
0.35
0.28
0.34
0.36
0.38
0.41
0.40
0.41
0.44
0.31
0.45
0.36
0.43
0.42
I
0.38
0.34
0.32
0.31
0.34
0.36
0.39
0.42
0.45
0.48
0.27
0.41
0.37
0.50
0.46
II
0.37
0.39
0.33
0.37
0.34
0.37
0.39
0.41
0.45
0.45
0.37
0.39
0.38
0.52
0.47
III
0.82
0.82
0.65
0.84
0.83
0.74
0.75
0.83
0.74
0.79
0.75
0.56
0.68
0.81
0.82
IV
0.66
0.68
0.73
0.77
0.76
0.71
0.75
0.99
0.90
0.97
0.69
0.94
0.67
0.80
0.82
V
0.47
0.43
0.53
0.54
0.47
0.53
0.55
0.59
0.60
0.66
0.38
0.63
0.52
0.59
0.66
VI
0.35
0.41
0.41
0.47
0.44
0.46
0.48
0.41
0.42
0.49
0.31
0.41
0.38
0.49
0.48
VII
0.38
0.35
0.34
0.40
0.38
0.39
0.39
0.40
0.40
0.43
0.21
0.35
0.34
0.39
0.35
VII
0.35
0.34
0.33
0.35
0.33
0.33
0.35
0.35
0.37
0.39
0.22
0.33
0.31
0.35
0.33
IX
0.29
0.28
0.28
0.30
0.28
0.29
0.30
0.33
0.34
0.37
0.19
0.35
0.26
0.31
0.29
X
0.33
0.29
0.28
0.31
0.28
0.30
0.33
0.33
0.35
0.38
0.19
0.39
0.25
0.32
0.31
continued ...
-------
Table 1.3 (cont)
River
Oder
Oder
Oder
Varta
Varta
Meric
Arda
Dnieper
Dnieper
Dniester
Neman
Neman
f* yo c c
u i USb
Section
Polacko
Slubice
Gozdowice
Poznan
Gorzow Wlk
Pazardzhik
Studen- Kadeneta
Kiev
Kremenshug
Zaleszczyki
Kaunas
Smalininkai
XI
0.40
0.43
0.47
0.39
0.49
0.20
0.14
0.30
0.28
0.22
0.54
0.68
XII
0.42
0.43
0.51
0.62
0.59
0.16
0.18
0.26
0.28
0.21
0.52
0.50
I
0.42
0.47
0.54
0.56
0.58
0.25
0.44
0.33
0.31
0.15
0.48
0.48
II
0.48
0.50
0.57
0.35
0.58
0.30
0.27
0.32
0.29
0.20
0.41
0.39
III
0.68
0.75
0.76
0.75
0.87
0.45
0.41
0.36
0.35
0.62
0.50
0.48
Months
IV
0.77
0.79
0.81
0.71
0.85
0.32
0.27
1.31
1.26
0.72
1.26
1.28
V
0.60
0.66
0.60
0.47
0.63
0.42
0.19
1.47
1.54
0.38
0.72
0.71
VI
0.42
0.38
0.48
0.33
0.44
0.13
0.14
0.61
0.70
0.30
0.56
0.46
VII
0.39
0.40
0.43
0.29
0.41
0.03
0.08
0.40
0.39
0.28
0.49
0.43
VII
0.36
0.37
0.38
0.26
0.41
0.01
0.03
0.34
0.33
0.27
0.47
0.38
IX
0.33
0.32
0.40
0.26
0.43
0.01
0.04
0.32
0.28
0.19
0.48
0.40
X
0.31
0.34
0.40
0.31
0.45
0.13
0.05
0.34
0.29
0.19
0 51
6.42
continued ...
-------
Table 1.3 (cont)
PO
River
Daugave
Daugave
Vltava
Vah
Danube
Danube
Olt
Cross
Section
Dvinsk
Plavinskaja GES
Modrany
Sal a
Budapest
Orsova
Rimnieu-Vilcea
XI
0.25
0.26
0.29
0.33
0.41
0.48
0.28
XII
0.26
0.27
0.31
0.37
0.35
0.48
0.24
I
0.21
0.22
0.35
0.31
0.51
0.42
0.22
II
0.20
0.20
0.36
0.29
0.59
0.50
0.26
III
0.22
0.21
0.55
0.68
Q.66
0.72
0.48
Months
IV
2.15
2.12
0.58
0.87
0.86
0.90
0.64
V
1.12
1.10
0.42
0.67
0.94
0.82
0.79
VI
0.42
0.44
0.34
0.59
0.90
0.71
0.64
VII
0.24
0.25
0.29
0.40
0.80
0.60
0.51
VII
0.22
0.21
0.20
0.33
0.70
0.47
0.34
IX
0.21
0.20
0.25
0.30
0.57
0.38
0.31
X
0.24
0.25
0.30
0.26
0.43
0.28
0.28
Si ret
Rocaciuni
0.22 0.14 0.12 0.12 0.47 0.80 0.82 0.52 0.44 0.33 0.23 0.19
Bistrita Bicaz
0.32 0.24 0.21 0.22 0.42 1.02 0.89 0.67 0.52 0.40 0.32 0.26
Seine
Paris
0.15 0.25 0.58 0.58 0.67 0.44 0.34 0.26 0.20 0.27 0.15 0.14
Garonne Mas D'Agenais 0.28 0.35 0.47 0.52 0.54 0.52 0.51 0.38 0.20 0.12 0.14 0.15
Dorgogne Dom(Cenac)
0.27 0.38 0.54 0.59 0.52 0.38 0.30 0.21 0.09 0.09 0.10 0.13
Loire Montjean
0.25 0.43 0.63 0.73 0.61 0.47 0.31 0.28 0.18 0.13 0.13 0.15
Rhone
Beacaire
0.48 0.54 0.59 0.55 0.63 0.59 0.60 0.62 0.49 0.43 0.39 0.37
Rhine
Bale
0.46 0.43 0.44 0.39 0.52 0.66 0.82 1.07 0.90 0.78 0.62 0.48
-------
K;
GJ
1.00
0,90
0,80
0,70
0,60
0,50
0,4)
0,30
0,20
0,10
0,0
Middle Oder
XI XII I
II III IV V VI VII VIII IX X
Ki iov.
1.00
090
0,80
0.70
0,60
0,50
0,40
0,30
0,20
0,10
nO.O
Lower Vistula
XI XII
II III ' IV ' V ' VI ' VII ' VIII ' IX '
Fig.1.2. Distribution of Kj10.A coefficients on lower and middle Vistula and Oder
-------
l 10V
0,90--
0,80 - -
0,70 -
0,60^
0,50 -
0.40-
0,30-1
0.20 i
0,10 H
0,0
Upper Vistula
Upper Oder (Scinawa)
XI 'XII '
III ' IV ' V ' VI ' VII ' VIII ' IX ' X
1,00
0.90
0,80
0,70
0,60
0,50
0,40
0,30
0,20
0,10
nO.O
Ngrew-OstroKeka
Warta-Gorz6w Wlk.
\San-Radomysl
XI XII I
III IV V VI VII l VIII ' IX ' X
Fig .1.3. Distribution of Kjw./t coefficients on Upper Vistula and Upper Oder and on San , Warta, Narew Rivers
-------
The coefficients of distribution for the large European rivers are given
in Figure 1.4. These results indicate that the variability of the coefficient
of distribution K.. ^ depends on the individual character of the river.
Coefficients K.. ^ may differ considerably in rivers flowing under similar
geographical cond-mons. The Neman, Daugave, Rhine and Rhone, as well as the
Danube, in its middle and lower stretches, are examples of significant differ-
ences of the coefficients of distribution K. lno;. The differences between
distribution coefficients in the Vistula and Oder Rivers amount to 0.20 in
winter and 0.10 in summer and autumn months. Slightly larger differences in
coefficients of distribution K. 1Q^ occur in the medium size rivers. In
Poland, these amount to 0.30 in winter and 0.20 in the summer critical period.
The differences between coefficients of distribution discussed here include
monthly magnitudes, critical periods when they occur within a year, and their
duration. This indicates the need for individual analyses of the rivers.
1.4 Flow Shortages
The purpose of the analysis of flow shortages is to investigate the
possibilities of low flow augmentation for power plant cooling systems. Flow
shortage is the difference between the historical flow which is not exceeded
90% of the time and the required low flow (Q ) with the defined control ratio,
(1.3)
where:
s = control ratio
Q = required low flow
Qr = mean flow of many years
Flow shortages are calculated from historical data on a daily, weekly, or
monthly basis. An analysis of flow shortages has been done for the Pulawy
cross-section on the Vistula River. Observations of the flows in the years
1921-1973 were used. Separate calculations were carried out for monthly and
daily flows, as well as for summer and winter flows. The months June through
October are considered the summer period.
The duration of flow shortages determined on the basis of daily flows
usually comprises a longer period than the basic period established on the
basis of the monthly flows. This causes the volume of shortages determined on
the basis of daily flows to be about 15% larger than the volume of shortages
established on the basis of monthly flows. The calculated values are pre-
sented in Table 1.4.
1.5 Maximum Reliable Water Temperatures
If the river in question is used for cooling steam power plants, it is
very important tat the duration of maximum temperatures is short. Natural
temperatures exceeding 25°C rarely last more than a few days in Polish rivers.
15
-------
K
K
110'/
1,00-
Q90-
0,80-
0,70
0,60
0,50
0,40-f
0,30
0,20
0,10-
0.0
Seine
XI XII I II III IV V ' VI VII VIII IX
hov. '
1,5
1,4-
1,3-
1,2-
1,1 -
1,0-
0,9-
0,8-
0,7-
0,6-
0,5-
0,4-
0,3-
0,2-
0.1 -
0,0.
n Dauggve-PlQwinskajg GES
Neman - 5malirtnl/< coefficients on large and medium rivers.
-------
TABLE 1.4. FLOW SHORTAGES FOR THE SUMMER WITH
DIFFERENT CONTROL RATIOS, s, FOR p=90%
Control
Ratio, s
0.30
0.35
0.40
0.45
The Sum of Monthly
Shortages (10xl06m3)
34
135
260
392
The Sum of Daily
Shortages (10xl06m3)
37
156
300
450
Coefficient
of Increment*
1.09
1.16
1.15
1.15
* Coefficient of Increment is the ratio of daily flow shortages to
monthly flow shortages.
During this period, rapid temperature changes of a few degrees Celsius may
occur.
To establish a reliable water temperature for power plant cooling, tem-
peratures which are not exceeded 95% of the period under investigation are
proposed; such temperatures (t95) should be calculated monthly. Calculations
show (Gadkowski 1972) that reliable temperatures (t95) are 1.0-2.0°C below
extreme natural temperatures.
The concept of reliable temperatures was introduced to thermal analysis
by other authors. Chauveau and Gras (1972) utilized this principle while
analyzing open cycle cooling for steam power plants. Temperatures exceeded no
more than 20 days of the year (t2oj) were accepted as reliable. The differ-
ence between t and t20 . in natural regimes is normally 2 to 3°C. In heated
waters, the difference is greater and stays within the limits of 3 to 4°C.
Flinspach (1973), in thermal calculations of the Neckar River, assumes
reliable temperatures as temperatures not exceeded 92.5% of the time in June,
July and August. Reliable temperatures are 1.0°C less than the maximum tem-
peratures in June and August and 3.0°C less in July.
In thermal calculations for the Rhine River (Arbeitsgemeinschaft 1971)
the reliable temperature was assumed to be the mean temperature of the lowest
low-flow period of 20 days duration for each year from 1947 to 1966. This
reliable temperature exhibits the same characteristics as for the Neckar
River.
Adoption of a reliable temperature lower than the maximum value is con-
firmed by the fact that measurements are usually made close to the river bank,
and those shallow, slow flowing waters heat up more rapidly than the deeper
mid-river waters. This phenomenon is reported by Cebotariev (1953),
Zelazinski (1961), Hatfield (1965) and others.
17
-------
2. Acceptable Temperature Increases in Free-Flowing Rivers
2.1 Variability of River Water Temperature
It is recognized that temperature changes caused by power plant opera-
tions can be of the same magnitude as temperature changes caused by a variety
of natural phenomena. It is also recognized, however, that the power plant
induced temperature increases are added to any natural changes, thus accent-
uating the increases. In any event it is instructive to review certain natu-
rally-caused temperature changes.
Calculations show that temperatures of various rivers situated in the
same climatic regions are different (Gadkowski 1976b). And, the larger the
area under investigation, the greater the difference between temperatures
taken simultaneously at different locations. This points to the opportunity
for varying cooling water discharge temperatures for various power plants
located within the area to accommodate these natural temperature variations.
In Poland, the differences between the summer mean monthly temperatures
of many years amounts to about 4°C. Differences between extreme temperatures
in the lower stretches of the Vistula and Oder Rivers are slightly smaller and
amount to about 3.0°C in the Vistula and to about 1.2°C in the Oder (Gadkowski
1976a).
Maximum differences between the mean monthly values are much higher and
in the summer amount to:
for the whole area, about 6°C;
for the lower stretches of the Vistula and Oder, between 4.0 and
5.5°C.
Maximum differences between 24-hour values in the summer are considerable and
range from 6 to 11°C.
Large temperature differences in the river may be caused by tributaries
which have different water temperatures than the main stream. Usually such
cases occur in rivers which are fed by glaciers or thermal sources. In Euro-
pean rivers, monthly temperature differences between the Rhone River and the
Arve River reach 9°C (Table 2.1), but between the Rhone River and the La Saone
River they are only 2.0 to 2.3°C (Remenieras 1972). Typically, temperature
differences are large between upper and lower river stretches, particularly
for rivers flowing from the mountains. In some cases, however, significant
differences in the lower stretches of large rivers are observed. For example,
in four cross-sections situated within a 145 km reach of the lower Rhone River
(Serriers, Valence, Viviera Bagnols sur Ceze), the following differences of
monthly river water temperatures between cross-sections were observed
(Gadkowski 1976b):
18
-------
TABLE 2.1. MONTHLY TEMPERATURE DIFFERENCES BETWEEN
THE UPPER RHONE AND ARVE RIVERS
Month 1964 1970 1971 1972 1973 Average
Jan. 2.2 1.1 2.3 2.2 3.1 2.2
Feb. 1.4 0.7 0.7 0.9 1.9 1.0
Mar. 0.2 0.2 0.3 0.4 1.1 0.4
Apr. 0.4 0.4 0.7 0.9 0.8 0.6
May 0.7 1.0 2.0 3.2 1.5 1.6
June 1.9 6.1 2.5 3.6 5.6 3.9
July 7.0 4.7 7.3 7.0 7.0 6.6
Aug. 7-4 9.0 9.7 7.4 9.6 8.6
Sept. 7.5 5.6 7.3 6.2 8.1 6.9
Oct. 6.9 7.4 4.5 4.9 5.9
Nov. 3.3 3.0 4.0 6.0 4.1
Dec. 3.1 2.6 2.8 4.1 3.1
19
-------
1970 1.8 to 4.4°C
1971 0.8 to 8.9°C
1972 0.1 to 6.4°C
Significant thermal changes may also be caused by discharges from storage
reservoirs, e.g., warmer discharges during the winter and cooler discharges
during the summer (May through August). The water discharged during the
summer can be as much as 12°C cooler than the natural down-stream temperature
(Cyberska 1975) and during the winter, 5 to 6°C warmer.
In summary, natural temperature changes do o.ccur regionally and locally.
In evaluating the range of these changes the following should be recognized:
changes of 1.0°C are typical of changes in all river systems.
changes of 4.0 to 8.0°C have been observed in the natural thermal
system of some rivers.
changes with 4.0 to 10.0°C can be caused by reservoir discharges.
2.2. Review of Temperature Increases Caused by Existing Steam Power Plants
2.2.1. Polish Steam Power Plants
Maximum temperatures recorded in Poland below power plants exceed 30°C.
The highest, recorded over a long time period in Poland, occurred in the
Vistula below the Skawina Power Plant in 1963 (Figures 2.1 and 2.2). It
should be pointed out that in the summer of 1963, water temperatures in the
thermal plume about 3 km downstream from the power plant were 34°C on several
days and temperatures exceeding 30°C were recorded for 10 consecutive days
from July 17 to 27. The maximum monthly temperature increase of the Vistula
River in the period of power plant operation exceeded 5°C in the summer and
7°C in the winter (Table 2.2). A maximum temperature of 36°C, was recorded in
the Nysa Luzycka River downstream from the Hirschfelde Power Plant (Stan-
genberg 1966). Very high water temperatures were also observed in the dis-
charge of the Stalowa Wola Power Plant, which has a series cooling system.
Waters discharged from the condensers installed at the first and second stage
are used for cooling the third stage. The mean monthly water temperatures at
the discharge of this power plant amounted to 43°C in the summer. Despite the
considerable temperature rise, the maximum temperature of the river fell quite
rapidly, and about 5 km downstream from the power plant, the maximum tempera-
ture increase in the heated plume was only about 3°C, while a mean value for
the whole cross-section was only about 2°C.
The Kozienice Power Plant on the Vistula River is another example. In
1974, the temperatures below the discharge oscillated around 30°C from May 15
to September 15. Maximum temperatures were 32.5°C. Maximum natural tempera-
tures the summer of 1974 in the region of the power plant intake were 21.0°C,
with a 24-hour maximum of 22.5°C.
Discharge temperatures exceeding 35°C were also reported for the Patnow
and Konin Power Plants (Figures 2.3 and 2.4).
20
-------
IN3
1 3 S 7 S 1! 13 6 17 19 21 23 25 27 29 1 35 7 9 11 13 15 17 19 21 23 25 27 9 31 1 3579 11 13 5 17 19 21 23 25 21
Fig.2.|, Temperature distribution in the thermal plume below the Skawina power plant
1963 (temper, measurement at 7:00,12:00 and 18:00)
-------
0
1963
Jan ' Febr. ' Mar. ' Apr. ' May June ' July ' Aug. Sept. Oct. Nov.
Daily temperatures in the Vistula River below and above the Skawina power plant in 1963
Dec.
Fig. 2.2
-------
TABLE 2.2. MONTHLY AVERAGE TEMPERATURE INCREASES IN THE VISTULA
DOWNSTREAM FROM THE SKAWINA POWER PLANT, °C
co
Year
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
max
ave.
Months
Nov.
2.36
3.95
3.45
2.69
1.98
3.76
3.28
5.40
3.25
4.10
1.93
3.88
3.03
5.40
3.31
Dec.
1.78
2.20
3.46
4.70
2.46
2.39
2.11
2.81
4.29
4.90
2.16
1.44
2.94
4.90
2.90
Jan.
3.06
2.85
4.63
7.23
2.89
3.24
3.15
2.12
4.68
3.57
2.20
4.70
4.05
7.23
3.72
Feb.
1.65
2.01
5.06
3.99
2.98
0.96
1.19
1.79
2.46
3.07
1.93
2.91
1.71
5.06
2.44
March
1.58
1.22
1.04
1.60
1.01
1.59
1.10
1.77
2.49
1.70
1.41
3.99
1.31
3.99
1.68
April
1.74
0.62
1.47
1.14
1.48
1.62
1.59
1.87
1.84
1.63
2.23
1.98
1.70
2.23
1.61
May
2.78
0.79
1.46
3.30
1.19
1.88
1.99
3.12
3.42
2.98
2.28
1.71
2.54
3.42
2.07
June
2.16
0.69
2.55
2.96
0.73
1.09
1.47
0.99
2.45
2.40
2.16
3.18
3.08
3.18
1.99
July
3.36
1.78
4.65
2.21
1.52
0.87
3.46
1.33
1.50
0.70
1.61
1.92
1.83
4.65
2.06
Aug.
1.79
4.22
4.92
3.69
2.02
1.15
3.64
1.00
2.30
1.22
4.72
0.66
2.44
4.92
2.60
Sept.
5.57
4.67
2.47
4.91
3.17
2.99
3.28
2.22
3.84
3.19
3.84
1.70
3.69
5.57
3.50
Oct.
4.81
4.67
1.20
4.05
3.58
4.13
3.98
2.29
4.56
2.34
3.87
2.27
3.63
4.81
3.49
-------
1 - natural temperature
2 - discharge temperature
10.
June
Aug.
Sept.
Fig. 2.J. Daily temperature changes in the cooling system in the Pqtnow
power plant
24
-------
ro
en
1- temperature at the intake
2 - temperature at discharge
of Pqtndw power plant
3 - temperature at discharge
of Konin power plant
- temperature at the end
of the Licheriskie Lake
at the distance of 13,8km
from the discharge
21VI-30 VI
6 VII-17 VI!
6 VIII-15 VIII
Fig. 2.4. Temperatures in cooling system of the Konin and Pqtnow steam power plants
in summer 1975
-------
2.2.2 French Power Plants
Maximum discharge temperatures from French power plants are at the level
of 30 to 35°C. Such temperatures were maintained for nearly 4 months during
1973 in the discharge of the Montreau Power Plant, and in July 1972 in the
discharge of La Maxe Power Plant. The highest discharge temperatures occur
downstream from the Blenod Power Plant. In summer they exceed 40°C, sometimes
reaching 43°C. Average daily temperature increases in the La Moselle River
downstream average about 10°C.
Downstream from other power plants, the maximum 24-hour temperature
increase is smaller, and according to Chauveau (1972) amounts to:
Marne River downstream from the Vaires Power Plant in - 1964- 3.2°C
1967- 5.8°C
1971- 8.1°C
Oise River downstream form the Beautor Power Plant in - 1965- 8.9°C
1967-11.5°C
1971- 9.8°C
Oise River downstream from the Creil Power Plant in - 1964- 5.3°C
Gave du Pou River downstream from the Artix Power
Plant in - 1971- 4.8°C
Loire River downstream from the Saint Laurent des
Eaux Power Plant in - 1971- 4.8°C
Maximum monthly temperature increases for a number of French power plants
are presented in Table 2.3.
The maximum monthly temperature increases below French power plants range
from 3.0 to 10.0°C:
temperature increases of 3.0 to 4.0°C occur from January to June,
temperature increases of 4.5 to 5.5°C occur in July, August, Novem-
ber and December,
temperature increases of 9.0 to 10.0°C occur in autumn months (Sep-
tember and October) when minimal flows appear in French rivers.
2.2.3 Other European Countries
Research carried out in Czechoslovakia (Kocakova 1976, Nauczno-Isslie-
dovatelskij Institut Vodnogo Chozjaistva, 1976) showed significant temperature
increases in the Morava River below the Godonin Power Plant and in the Oslava
River below the Oslaviany Power Plant.
Mean temperature increases in the Morava were from 1.6 to 4.8°C in 1972
and in 1973, from 0.6 to 9.9°C. For the Oslaviany Power Plant water tempera-
tures in the discharge channel were:
26
-------
TABLE 2.3. MONTHLY AVERAGE MAXIMUM TEMPERATURE INCREASES AT FRENCH POWER PLANTS, °C
Power Plant
Saint-Ouen
Champagne sur
Oise
Porcheville
Gennevil 1 iers
Creil
Vaire sur
Marne
Vitry
Saint Laurent
des Eaux
Montereau
La Maxe
Blenod
Maximum
Nov.
1.49
3.35
2.11
1.71
2.1
3.50
4.7
4.3
3.6
4.2
5.5
5.5
Dec.
1.38
2.88
1.70
1.33
2.0
2.50
4.5
2.1
0.6
4.0
4.6
4.6
Jan.
1.28
2.44
1.32
1.21
1.9
3.65
3.6
1.5
3.3
3.8
2.7
3.8
Feb.
0.71
1.19
0.60
0.60
1.6
1.23
1.9
1.0
1.7
3.5
2.5
3.5
Mar.
0.93
1.85
0.92
0.60
1.4
1.80
2.5
1.3
1.7
3.6
3.7
3.7
Apr.
0.58
2.20
1.33
0.51
1.2
2.40
2.5
1.6
3.0
3.4
2.8
3.4
May
0.88
1.45
0.83
0.60
1.3
1.65
2.6
2.2
1.8
3.1
2.7
3.1
June
1.44
1.92
1.43
0.70
2.5
2.10
2.9
2.3
2.4
2.3
1.6
2.9
July
1.63
3.31
2.10
1.41
3.8
3.40
3.5
3.0
4.7
3.2
2.6
4.7
Aug.
2.00
3.39
3.04
2.10
3.9
3.90
2.6
2.5
4.5
3.1
2.9
4.5
Sep.
2.01
3.97
3.10
2.32
4.6
5.86
4.0
5.1
4.8
3.9
9.1
9.1
Oct.
1.91
3.72
2.57
2.24
3.8
7.04
4.9
3.4
2.5
3.2
9.8
9.8
Years
1964-1973
1964-1973
1964-1973
1964-1973
1964-1973
1964-1973
1964-1973
1969, 1972
1973
1971, 1972
1973
1972, 1973
1971
-------
Summer Temperatures
Temperature in the in the River 0.5 km
Year Discharge Channel Below the Discharge
1972 from 14.6 to 34.2°C
1973 from 18.5 to 36.8°C 33°C
1974 from 18.0 to 38.5°C 30 to 31°C
Temperature increases in the Neckar River in West Germany (Flinspach
1973), occur during critical conditions and amount to:
4.6°C - below the Altbach Power Plant
3.8°C - below the Marbach Power Plant
6.6°C - below the Heilbronn Power Plant
4.4°C - below the Obringheim Power Plant
2.3. Legal Limitations of Temperature for Open Cycle Cooling
of Steam Power Plants.
An analysis of legal regulations indicates two different tendencies in
the field of thermal limitations for open cycle cooling of steam power plants.
One, there is a tendency to strengthen the limitations in a number of coun-
tries; yet permits issued for particular power plants often require deviations
from these limitations.
In the regulations of different countries and in permits issued for
specific plants, significant divergence concerning the reference point of
admissible temperatures is found. For example, the following points are used
in various regulations:
- in the discharge channel
- at the end of discharge channel
- in the thermal plume at some specified distance from
the discharge point
- mean temperature in the river below discharge
Thermal standards of some European countries are presented for comparison
in Table 2.4, and the required temperatures for Polish power plants are pre-
sented in Table 2.5.
The problem of thermal standards is the subject of long-term research in
Comecon countries. In 1972 a plenary meeting of the Directors of Water Man-
agement of the Comecon countries took place in Warsaw during which a recommen-
dation was approved to allow a 5°C increase in mixed river temperature over
the temperature of the intake water. This recommendation was accepted by
Polish, Czechoslovakian and Hungarian delegations. However, additional recom-
mendations were included (SEV 1976):
below the discharge, maintaining a zone of cold water one third the
river's width,
28
-------
TABLE 2.4. THERMAL STANDARDS IN SOME EUROPEAN COUNTRIES
Country
Temperature in
the Discharge
Channel
Temperature Down-
stream from the
Discharge
Permissible Temp-
perature Increment
Downstream from
Discharge
Poland
22°C or 26°C
depending on the
stream classifi-
cation
If natural temper-
ature exceed the
temperature limits,
a 2°C AT is allowed
Czechoslo-
vakia
Holland
West 30 - 33°C
Germany
Switzer- 30°C
land
Hungary
U.S.S.R.
5°
32 - 37°C
28°C 3 - 5°C
25°C
30°C
For regions with
cold water fish -
20°C in the summer
and 5°C in the win-
ter. For all other
regions - 28°C in
the summer and 8°C
in the winter
29
-------
TABLE 2.5. PERMISSIBLE TEMPERATURE DECREASES AT POLISH POWER PLANTS
CO
o
Power Plant Receiving
Stream
1 2
Zeran
Steam Power Vistula
Plant
Siekierki
Steam Power Vistula
Plant
Ostrokeka
Power Plant Narew
Rybnik Reservoir
Power Plant on the Ruda
River
Kozienice Vistula
Class of
Receiving
Stream
3
I
I
II
unclass-
fied
I
Permissible Permissible Temperature in the
Temperature Receiving Stream
in the Dis-
charge Channel
4 5
35°C not described
Permissible temperature increase in the
discharge, 10°C
35°C Temperature increment in the river down-
stream from the discharge, 2°C
~?or 1 km downstream from the discharge after
complete mixing, 28°C
34°C not described
1 km downstream from the discharge after
complete mixing:
34°C - at natural temperatures less than 26°C
- permissible temperature, 26°C.
- at natural temperatures greater than
26°C, permissible temperature increase
is 2°C, but temperature must be lower
than 29.6°C.
continued ...
-------
Table 2.5 (cont.)
Stalowa Wola
Power Plant
San
OJ
Skawina
Power Plant
For river flow less
than 30 m3/s, 38.5°C
For higher river
flows, limitations
are not described.
(not described)
Patnow
and Konin
Power Plants
Konin I
Lakes
complex
34°C In the northern part of Lichenskie
Lake (13.8 km from the discharge)
during the summer - 30°C for 80 hours
- 33°C for 20 hours
Skawina
River
Allowable
In the Skawinka River, 100 m downstream
discharge, 30°C.
In the Vistula River, 4 km downstream
from the Skawina mouth, 26°C.
In the Vistula River, 10 km down-
stream from the Skawina mouth, 22°C.
Temperature increase after mixing in
the Vistula, 6°C.
-------
limiting the temperature of water in lakes to 28°C (without specify-
ing how to measure or define the limitation),
In France, three options are used to limit discharge water temperatures
from power plants:
a. a temperature of 30°C at the discharge channel below power
plant,
b. a temperature of 30°C related to the thermal plume in the
cross-section specified in agreements with water management
authorities,
c. a mean temperature of 30°C in the cross-section of the river
below the discharge point.
The decisions and specifications regarding the selection of which option is
used is made by regional water resources managers considering both river flow
and biological quality.
In relation to existing French power plants, it is pointed out that in
the Paris region, recognized as a protective zone, the interpretation present-
ed in option "a" is obligatory. It applies to Champagne sur Oise,
Porcheville, Vitry sur Sein and other power plants. In other regions, the
interpretation is different, e.g. in the case of the La Maxe Power Plant, the
mean temperature from four measuring points in the discharge from a prelimi-
nary cooling reservoir is the reference temperature. An interesting way to
meet an imposed temperature limitation is found at Porcheville, where an
additional quantity of water is pumped into the channel directly from the
river. This "solution" allows an increase in the output of the plant. While
appearing to meet the legal conditions of option "a", this method corresponds
more closely to option "c" (Gadkowski, Tichenor, 1976).
In West Germany, the temperature limits are related to receiving water
dissolved oxygen concentration. Use of combined cooling systems which provide
aeration (e.g., sprays, cooling towers) allows higher discharge temperatures.
An economic analysis has been carried out that indicates the advisability of
modifying the present German standards. The new proposals are:
admissible temperature rises in condensers of 15°C,
admissible temperatures in the discharge channel of 35°C,
admissible increase of river water temperature of 5°C.
The enforcement of these standards will be combined with simultaneous con-
struction of water aeration equipment in power plants. The new standards have
been temporarily accepted by the German water authorities and are under review
for permanent approval.
In reviewing the above discussion of thermal regulations, it is empha-
sized that governmental entities often modify regulations; thus, the specific
citations above may not be applicable at this date.
32
-------
2.4. Impact of Heated Water on the Oxygen Balance In Receiving Water
Investigations of oxygen balance in water used for cooling purposes
(Goubet 1967, Hawes 1970, Jensen 1974, Khalanski 1973, Dojlido 1976, Kiriak
1976, SEV 1976) show that when oxygen content in the intake water is high,
there is a significant drop of oxygen content after the water passes through
the cooling cycle of a power plant. In the case of low oxygen content in the
intake water, it is enriched in oxygen after passing through the cooling
cycle. Figure 2.5 illustrates this phenomenon. On the basis of published
results, a regression equation was developed which relates change in oxygen
concentration to intake oxygen concentration:
A 02 = A a + B (2.1)
where:
A 02 = change in oxygen content (mg 02/dcm3),
A and B = coefficients of regression equation,
CT = intake oxygen content or saturation
The coefficients for the above equation are presented in Table 2.6.
2.5. Impact of Heated Water on Fishes
Lethal temperatures have been determined for some cyprinides species
existing in Poland (Table 2.7) (Horoszewicz 1976).
Comparisons show that under extreme river temperatures, critical condi-
tions for fish may occur. In particular, this refers to power plant discharge
channels and mixing zones. Practice shows, however, that if such zones don't
cover the whole river cross-section, they are avoided by adult fish. To
minimize the negative impact of extreme temperatures on fish, river water
temperatures should not exceed 30°C and temperatures in discharge channels
should not exceed 35°C.
2.6 Proposals for Permissible Temperatures
Permissible temperatures at three different reference points are pro-
posed:
a. permissible discharge water temperature, 35°C
b. permissible temperatures downstream from the discharge, 30°C
c. Permissible temperature increment above the intake water tem-
perature (natural):
4°C in summer (June, July, August)
5°C in September
6°C during the rest of the year.
33
-------
1
2
3
4
5
power plants:
Kozienice and Stalowa Wola - discharge
Kozienice bank at 428,5 km of river course
20km downstream from the discharge
Chesterfield : discharge
Chesterfield -4,7km below the discharge
Chesterfield - 6,0 km below the discharge
intake water saturation
120
140 70
u
Changes in oxygen content after passing
through cooling systems in the San,Vistula
and James Rivers
.+ 1 1 i—»•
8 10 12 14
oxygen content at the
intake mg 02/dcm3
Changes in oxygen content after passing
through the cooling systems in the Morava
and Oslava Rivers
Fig. 2.5. Changes in oxygen content after passing through the cooling systems of steam power plants
-------
TABLE 2.6. A, B, AND a AT SELECTED LOCATIONS
No. Place of
Investigation
1. Discharge channel
of the Kozienice
and Stalowa Wola
Power Plants
Reference
Point
oxygen sa-
turation,
in %
B A R a
(Corre-
lation
Coeffi-
cient)
1.837 -0.034 -0.504 0.879
Number of
Samples
51
2. The left bank of
Vistula River 2
km downstream
from the discharge
of the Kozienice
Power Plant
1.260 -0.018 -0.539 0.483
35
3. The Chesterfield
Power Plant -
discharge channel
1.623 -0.0323 -0.835 0.558
23
4. The Chesterfield
Power Plant 4.7
km downstream from
the discharge
2.996 -0.0473 -0.798 0.960 117
5.
6.
The Chesterfield
Power Plant 60 km
from the discharge
The Morava and
Os lava Rivers
3.138 -0.0476 -0.788 0.931
oxygen
content, 3.122 -0.474 -0.863 0.839
in mg/dem3
87
62
35
-------
TABLE 2.7. THE LETHAL TEMPERATURES OF CYPRINIDES, °C
1
Fish Species
Abramis abrama
Gob 10- gob io
Tinea tinea
Scardinius ery-
throphthalmus
Leuciscus cep-
halus
Alburnus alburnus
Leuciscus idus
Gasterosteus
aculeatus
Rhodeus
sericeus
Carassius
carassius
Carassius aura-
tus gi belie
Cyprinus carpi o
Ictalurus
nebulosus
Micropterus
salmonides
Esox lucius
Acerina cernua
Perca fluvia-
til i s
Months
March April May June July August
27.5 30 31-33 33-34 31
-28.5
28 28.5
31 32-34 33 34
32 33
34 34
33
27 28 28 29
29
31-32
34-36
30 32 34 36 38-41
26 36
30-33 34 35-37
28 32 34 33
32-33
28 31 34
28 29 32 31 32
Lucioperca lu-
croperca
29
34
34
36
-------
3. Variability of Steam Power Plant Load
3.1. Introduction
Previous investigations (Dobrzanska 1963, Kopecki 1958, Kwiatkowski 1969)
showed that electrical system load has a natural character. Important factors
are climatic conditions, geographical situation, economic development of the
country, and other factors. It is possible to identify distinct daily, week-
ly, and yearly cyclic changes in electrical system operations which seriously
impact the load cycles of particular power plants.
The correlation between system load changes and power plant load changes
depends on several energy system characteristics:
variability of power demand during day, week, and year,
mix of power in electrical systems (hydropower plants, pumped stor-
age plants, gas turbine, fossil and nuclear steam power plants),
regulation of operating schedules for hydro, pumped storage, gas
turbine and steam power plants, utilizing both base and peaking load
facilities,
economic load distribution between different power plants, operating
in a connected electrical system.
Taking into account the above dynamics and complexity of electrical
system operation, emphasis was placed on analyzing plant operation on the
basis of electrical system data. The analysis is supported by existing steam
power plant production data.
The main aim of the analysis was to determine the average monthly coeffi-
cients of installed capacity utilization in power plants, depending on the
expected time of their operation during the year. In these investigations,
attention was also given to the relationship between power plant operating
time, cooling system operating time, and daily load changes.
3.2. Daily Load Changes
To establish daily load changes of a steam power plant complex, an analy-
sis was conducted on data from 11 power plants operating in the summers of
1972, 1973 and 1974.
Data were analyzed separately for two groups of power plants:
all power plants operating with open cycle cooling systems,
37
-------
6 large power plants operating with open cycle cooling systems.
Average load was described for holidays, days before and after holidays, and
other working days. The range of changes in both groups of power plants was
the same. For example, in Table 3.1, results of daily load changes in the
second group of power plants are presented. The results obtained show that
the load before and after holidays of this group of power plants is at the
level of the average monthly load.
TABLE 3.1. DAILY LOAD CHANGES IN LARGE* POLISH STEAM POWER
PLANTS WITH OPEN COOLING SYSTEMS (%).
Year
1972
1973
1974
Month Typical Working
Day
June
July
August
June
July
August
June
July
August
104
116
100
101
no
107
101
105
105
Days Before
and After
Holidays
96
82
99
97
98
99
102
99
99
Holidays
89
80
97
85
86
92
91
89
84
Average 106 97 88
100% - Average monthly load
* including - Patnow - 1400 MW
Konin - 600 MW
Rybnik - 800 MW
Kozienice - 1600 MW
Stalowa Wola - 450 MW
Ostroleka - 600 MW
On typical working days it is 5 to 10% higher and during holidays it drops 10
to 15%. Larger load changes can occur in single power plants.
To characterize load changes for a single power plant, a plant of 550 MW
capacity and 7,000 h operation time in the year was analyzed. Average monthly
coefficients of power utilization (load factor) at the Skawina Power Plant
were:
38
-------
Month 1972 1973 1974
June 0.79 0.73 0.70
July 0.77 0.66 0.76
August 0.73 0.65 0.79
Additional data for the Skawina Plant are presented in Table 3.2 and Figure
3.1. These results show that daily load changes can be quite severe.
3.3. Steam Power Plant Operating Time
As shown in UNIPDE (Union Internationale des Production et Distributours
d'Energie Electrique) papers and other references concerning load changes of
electrical systems in countries situated in the middle latitudes, asymmetrical
load distributions caused by geographical location appear during the year.
For such load distributions, system load in corresponding months in the first
and second half-years will be equal. Actually, a constant energy demand
increment means that during the second half-year a higher demand is observed
than in the first half-year. This increment is nearly constant and the mean
for all world electrical systems is 7.2%. In Polish electrical systems, some
load deformation is observed. It is caused by increased electric energy
utilization for heating and other purposes, so the system load is higher in
the first half-year. Comparing this trend to open cooling cycle operation,
this corresponds with the period of increased water resources in the rivers.
Other factors which are not considered here may have significant impact
on load distribution throughout a year. Electrical system load changes re-
quire high elasticity in electric energy production, thus quite a large part
of the installed capacity in electrical systems is not utilized over an annual
cycle. There is a rule in electric power system organizations that the total
installed capacity in the system depends on the maximum peak load plus some
reasonable reserve capacity (15-25%).
As a characteristic indicator of steam power plant operation, the annual
full load operation time was used. The annual full load operation time equals
the annual load factor times 8,760 hours per year. This indicator is provided
to indicate yearly electric power production. Full load operation times of
base load steam power plants in different countries are presented in Tables
3.3 and 3.4 (Zarzycki 1976).
Taking into account full load operation times of fossil fueled power
plants, it is possible to divide them into three groups:
Annual Full Load
Operation Time Group of countries
4,000 to 5,000 hours Czechoslovakia, Belgium
Spain, West Germany, USA.
5,000 hours Poland, USSR
5,500 to 6,000 hours Rumania, East Germany
39
-------
load
-£»
o
days
VI
VII VIII
1972
VI
VII
1973
VIII
VI
VII
197A
VIII
• Sundays and holidays
Fig.3.1. Daily load in power plani of yearly operation time T= 7000 hours
-------
TABLE 3.2. FREQUENCY OF MAXIMUM DAILY LOAD IN A
POWER PLANT WITH T = 7000 h OPERATION TIME
Daily
Load
% June
100 3
96 1
92 1
87 1
83
1972 1973 1974
July August June July August June July August
1
1
3 4
652 143
264 1 6
Sum of
i ^^•••^^^^^•^^^••a
Number
4
2
8
22
19
cases
^^_»^^— ^p^*«NBV*M^V
%
1.4
2.1
5.0
13.0
19.9
-------
TABLE 3.3. TIME OF FULL LOAD INSTALLED CAPACITY
IN SOME COUNTRIES (HOURS)
Country
Years
1967
1968
1969
1970
1971
Poland
Czechoslovakia
East Germany
Romania
U.S.S.R.
Belgium
France
Spain
West Germany
U.S.A.
East Germany
U.S.S.R.
England (CEGB)
France
Spain
West Germany
Conventional Power Plants
5005 5164 5037 5025 4780
4221 4377 4627 4446
5605 5937 5897 5638
5613 5884 5540 5485
5226 5116 5098 4965
3741 3997 4383 4620 4608
4410 3948 4279 4060 4531
4027 4052 3419 4127
4067 4464 4888 4793
4514 4629 4673
Nuclear Power Plants
4657 5600 6071 6014
1622 2092 5442
6220 6323 6023
3938 3510 3245 3730 4455
3376 5110 5571
3651 2004 5314 5843
42
-------
TABLE 3.4. EXPECTED TIME OF FULL LOAD INSTALLED CAPACITY
FOR NUCLEAR POWER PLANTS IN SOME COUNTRIES (HOURS)
Country
Bulgaria
Hungary
West Germany
Czechoslovakia
Yugoslavia
Austria
Belgium
Denmark
West Germany
Switzerland
Sweden
Canada
Japan
India
Austral ia
1980
5500
6818
7000
7058
5583
6500
7000
7080
5275
7037
6570
4872
6963
7242
6000
1985
6000
6914
6666
7037
5555
5900
6800
7070
-
6889
6440
-
6916
7407
6000
Years
1990
7125
6959
6333
7016
6071
5400
6600
6460
5300
6923
5600
6242
6910
7456
6000
1995
6917
7000
6000
6818
6417
-
-
-
-
6333
5625
6230
6470
7466
-
2000
6842
7000
6000
6479
6364
-
-
-
-
5917
5580
6250
6895
7483
4868
43
-------
Table 3.4 provides projected full load operating time data for nuclear
power plants up to the year 2000. In many countries it is expected that in
the future, nuclear plant full load operating time will be prolonged up to
7,000 hours. The problem of power systems operating time for conventional and
nuclear power plants should be considered separately. For example, referring
to Table 3.4, the high power plant full load operating time in India is caused
by the expected constant energy utilization for irrigation purposes. Simi-
larly high values in Switzerland are caused by the electric power system
structure which includes substantial hydropower. To cover basic energy de-
mands, Switzerland is building nuclear power plants instead of fossil-fueled
plants.
Data on Polish power plants indicate that the full load time also depends
upon the type of cooling system used (Table 3.5). These results show that in
the Polish electrical system power plants operating with open cooling systems
have higher load factors than those operating with closed cooling systems.
The Polish Board of Energetics has predicted full load operating times for
various sized units through 1990 (Table 3.6).
3.4 Monthly Coefficients of Installed Capacity Utilization
In previous investigations of open cycle cooling systems, the distribu-
tion of monthly power plant utilization has been inadequately treated. Prob-
lems of monthly production are acknowledged as important, and in this report
they are analyzed using different calculation methods such as:
a. statistical analysis of production changes,
b. repairs schedule,
c. cosine model,
d. BETA distribution model.
3.4.1. Statistical Analysis of Production Changes
The statistical analysis of production changes was carried out by the
Polish Energetic Board (Zarzycki 1976). It was established that a reasonable
period for characterizing operating conditions of large steam power plants was
the period after 1967; thus, the statistical data from 1967-1973 were used.
Results of the analysis are presented in Table 3.7 and Figure 3.2. Differen-
ces between average, maximum and minimum values are not large (Figure 3.2),
and the range of these differences is nearly constant during the whole year.
In addition, the Energetic Board conducted analyses which showed that monthly
coefficients of capacity utilization will be at the present level up to 1980
and will drop slightly thereafter (Table 3.8).
3.4.2. Repairs Schedule
The analysis of power plant unit repair schedules allows the evaluation
of power production during the year and the possibility of shifting part of
the load of power plants operating with open cooling systems to power plants
operating with closed cooling systems. Polish power plants are down for re-
pair an average of 7.4% of the time.
44
-------
TABLE 3.5. TIME OF FULL LOAD CAPACITY IN POLISH POWER PLANTS,
UNITS OF 120 AND 200 MW (hours).
Year
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
Average
Power Plant With
Open Cooling
System
4,467
5,438
5,666
5,694
6,531
6,248
6,160
5,816
5,955
5,926
6,050
Power Plant With
Closed Cooling
System
5,258
5,468
5,488
5,599
5,291
5,486
5,287
5,365
5,775
6,070
5,553
Average
for both
Groups
5,150
5,453
5,517
5,617
5,610
5,726
5,565
5,492
5,884
6,016
5,692
TABLE 3.6. EXPECTED TIME OF FULL LOAD INSTALLED CAPACITY
FOR POLISH POWER PLANTS IN 1980, 1985, AND 1990.
Size of Unit
120-200 MW
360-500 MW
Nuclear Units
440-500 MW
Total
Year
1980
1985
1990
1980
1985
1990
1980
1985
1990
1980
1985
1990
Cooling
Open
6,000
5,830
5,340
5,800
6,100
5,400
6,100
6,000
5,799
5,688
System
Closed
5,500
5,350
4,900
4,900
5,200
5,600
5,600
5,388
5,269
5,387
Average for
Both Groups
5,760
5,606
5,135
4,900
5,314
5,657
5,400
6,000
5,675
5,487
5,505
45
-------
TABLE 3.7. INSTALLED CAPACITY UTILIZATION COEFFICIENTS FOR
LARGE POWER PLANTS, 1967-1973 (%)
" — —
Months
January
February
March
April
May
June
July
August
September
October
November
December
•
Power Plants With
Open Cooling Systems
Average
71.5
71.5
71.7
67.7
69.6
69.0
59.9
57.2
69.0
72.4
73.3
75.1
Minimum*
Maximum
63.7
74.4
55.6
79.5
63.1
79.3
60.8
78.3
60.3
86.6
62.9
78.6
53.7
66.1
51.9
68.5
66.8
72.5
59.8
79.8
59.7
83.8
70.4
86.0
Power Plants With Average for
Closed Cooling Systems Both Groups
Average
69.2
68.4
65.8
61.5
60.0
55.9
54.4
57.1
60.4
66.5
70.2
70.4
Minimum
Maximum
63.5
76.6
61.7
7374
60.0
72.3
57.9
65.1
57.1
64.1
45.4
62.9
47.0
61.5
51.0
64.7
51.1
67.3
61.9
70.9
62.2
76.5
69.8
75.4
Average
70.0
69.6
67.6
62.9
62.2
59.5
55.7
57.2
63.0
68.4
71.1
71.7
Minimum
Maximum
64.1
74.1
64.2
73.6
63.9
72.8
59.5
65.0
59.0
64.9
51.5
63.1
51.6
60.3
54.1
62.7
57.5
69.1
65.0
73.3
63.3
75.6
68.8
74.7
* Mi
nimum _ mi
nimum monthly
value
Maximum maximum monthly value
46
-------
U)
"c
o
s.
100
•8 90
8 80
o
o 70
^-
.§ 60
50
Q.
O
0
40
30
"8
=3 20
-*-•
c
- 10
IV
VI
VII
VIII
IX
XI
XII
Fig. 3.2. Average real coefficients of installed capacity utilization in Polish multiunit steam power plants
in period 1967-1973
-------
TABLE 3.8. EXPECTED INSTALLED CAPACITY UTILIZATION
COEFFICIENTS FOR STEAM POWER PLANTS (%)
Month
January
February
March
April
May
June
July
August
September
October
November
December
Average For
Period
1967-1973
70.0
69.6
67.6
62.9
62.2
59.5
55.7
57.2
63.0
68.4
71.1
71.7
1980
68.9
69.3
67.2
63.1
63.1
60.8
55.7
57.5
63.1
67.8
69.8
70.8
1985
66.8
67.1
65.0
61.1
60.8
58.3
53.8
55.6
60.6
65.6
68.0
68.8
1990
66.9
67.2
65.0
61.1
60.8
58.3
54.1
55.7
61.1
65.9
68.4
69.3
The Energetics Board investigated 3 variations of repair schedules of
power plant units operating with open cooling systems:
basic variation - presently existing repair schedule
maximum variation - assumes all units are repaired within a 3 month
period,
optimum variation - assumes
can occur simultaneously.
repairs on two units in one power plant
The optimum variation takes into account the possibility of optimal organiza-
tion of repair brigades and equipment necessary for repairs (cranes, repair
fields, etc.). The optimum variation was designed to allow load shifting
between two groups of power plants (with closed and open cooling systems)
without additional investment inputs. Monthly indicators of capacity de-
creases due to repairs are presented in Table 3.9. These values show that by
changing repair schedules it is possible to reduce, in the summer period, the
mean load of power plants operating with open cooling system by about 5% of
installed capacity (i.e., the difference between the basic and optimum varia-
tions).
3.4.3. Cosine Model
3.4.3.1. Analysis of Calculation Method
The cosine model analysis of steam power plant operations was conducted
using data from 1958-1968. The air of the investigation was to describe the
maximum monthly average coefficients of installed capacity utilization in
power plants at an assumed probability of occurrence in relation to power
plant operating time throughout the year.
48
-------
TABLE 3.9. MONTHLY INDICATORS OF CAPACITY DECREASES
DUE TO REPAIRS (%)
Month Basic
Variation
January
February
March
Apri 1
May
June
July
August
September
October
November
December
-
1.1
6.0
5.2
6.8
18.4
19.6
21.9
9.6
0.3
-
~
Maximum
Variation
-
0.4
-
-
0.4
27.2
32.6
28.6
0.4
-
-
—
Optimum
Variation
-
-
-
-
6.8
24.6
26.7
25.2
5.6
-
-
—
Disposable
Capacity*
100
100
100
100
93.2
75.4
73.3
74.8
94.4
100
100
100
* assumes Optimum Variation
As the basis of the calculations, the following trigonometric function
was used, which describes the monthly average coefficient of power utlization:
where:
g
imax
9imax=(fi
cos a)
(3.1)
monthly average maximum coefficient of installed capacity
utilization in a steam power plant at the assumed prob-
ability of occurrence,
function of b, of the form, a=xb + yb2, where x and y are
constants,
yearly average coefficient of installed capacity utiliza-
tion, where
f.
Af.
a =
b =
8,760
= 1.14 TQ 10"4 (%)
(3.2)
annual full load operating time, hrs,
monthly average correction coefficient,
correction coefficient defining the relationship between the
g. value and the assumed probability of excess,
angle designated by the function of month, i,
49
-------
The base data included the installed capacity of specific power plants and the
monthly gross production (MWh). At the same time, monthly average coeffi-
cients of installed capacity utilization in particular years and power plants
were described. These coefficients were calculated using the formula:
fl =-^100 (3.3)
o
where:
g. = monthly average coefficient of installed capacity utilization
1 %.
A = monthly gross production, MWh.
P = installed capacity in a particular month, MW.
h = number of hours in the month.
Power plant operating time during the year depends on different factors
such as breakdowns, planned and unplanned repairs, system load changes, etc..
Therefore, for each power plant, monthly average coefficients of capacity
utilization for the whole period under investigation were calculated. These
coefficients eliminate to a remarkable degree the details of power plant
operation, while exhibiting the seasonal nature of their operation. To calcu-
late these coefficients, only full years were considered, excluding the first
year of operation, when operating rules are different than for established
plants. Calculated coefficients were the basis for future calculations and
analyes.
Coefficients of installed capacity utilization were computed using the
assumed trigonometric model according to formula:
gl = b + a cos a (3.4)
The comparison of real and calculated values by equation 3.4 was done using
the least squares method. At the given 12 monthly g. values, the regression
curve was defined by equation 3.4. Deviation of the calculated values g1. from
the actual values g. is given by: 1
gl = gi - b - a cos a (3.5)
12
I g. cos a
where, a = 1-1 (3.6)
50
-------
12
Z 9i
and, b = vj _ (3.7)
12
a and b are defined as:
a = yearly oscillation amplitude,
b = sinusoid ordinate,
The next steps include the calculation of:
a) ordinate of points on regression curve using equation 3.4
b) sum of squares (g. - gl)2 (3.8)
c) sum of squares (g. - g.)2 (3.9)
12
1 9i
d) g< = 1-1 (3-10)
1 12
e) correlation indicator:
(3.1D
- gimax)2
f) standard deviation of real monthly average g. values from their
calculated values g1.:
(3.12)
Differences between real coefficients g.. and coefficients gl are called devia-
tion coefficients.
The magnitudes of deviation coefficients are:
51
-------
± 1% from real values - 37.4% of cases investigated
± 2% from real values - 67.8% of cases investigated
± 3% from real values - 83.8% of cases investigated
The small deviations obtained in the analysis show that monthly average coef-
ficients of installed capacity utilization for particular power plants are
similar to those assumed in equation 3.4.
3.4.3.2. Amplitude of Yearly Changes of g. Coefficients
Using values obtained from equations 3.6 and 3.7 by the least squares
method, the correlation between function "a" and "b" was determined [a =
f(b)]. As a result, the following quadratic equation was obtained:
a1 = 0.134b - 0.0008 b2 (3.13)
On the basis of the new values of "a" from equation 3.13, the capacity utili-
zation coefficients were calculated again:
g!1 = b + a1 cos a (3.14)
Further analysis refers to installed capacity utilization coefficients
calculated on the basis of equation 3.14.
3.4.3.3. Designation of Correction Coefficient, f .
Coefficient f. is a correction of the assumed trigonometric model adop-
ting it to actual power plant operations. Coefficient f. equals the average
f'. individual coefficients designated separately for each month for the inves-
tigated power plants. Only the years when the power plant operated during a
complete annual cycle were used. Individual correction coefficients f! were
obtained from equation: 1
gi Ts
f- = -4- = -f1- (3-15)
i q. T
q.
yi r
where:
g. = monthly average real coefficient of installed capacity utili-
zation (from the equation 3.3),
g'. ' - theoretical coefficient of capacity utilization (from equation
3.14),
TS - yearly average of full load power plant capacity utilization
time (h/year),
Tr - time of full load power plant utilization in the year under
investigation (h/year).
Final values of f . were calculated for particular months using equation:
52
-------
132
Values of f. are given below:
Jan - .0990 May - 0.972 Sept - 1.012
Feb - 1.008 June - 1.003 Oct - 1.007
Mar - 1.005 July - 0.999 Nov - 1.013
Apr - 0.971 Aug - 1.011 Dec - 0.997
The calculated f. coefficients are nearly all equal to 1, which confirms the
conclusion that under average conditions the installed capacity utilization
coefficients are similar to the assumed model presented by equation 3.14.
3.4.3.4. Designation of Af. Coefficient
The difference fl - f. is the Af. coefficient. Values of these dif-
ferences, called f. deviations, were investigated for 132 cases. To describe
the probable values of Af. , it was assumed that deviations are random vari-
ables of the continuous type and normally distributed. Assuming the distribu-
tion is centralized around f. values, the probability of deviations may be
calculated from using a Gaussian (normal) distribution according to the fol-
lowing equation:
In equation 3.17, a is the standard deviation and for particular months it is:
Jan - 0.119 May - 0.127 Sept - 0.095
Feb - 0.124 June - 0.139 Oct - 0.090
Mar - 0.109 July - 0.117 Nov - 0.094
Apr - 0.098 Aug - 0.113 Dec - 0.099
= number of standard deviations from mean (f.) such that (fl + f..)
will not be exceeded p % of the time.
Values of A f. for a given probability are presented in Table 3.10.
3.4.3.5. Analysis Summary
The analysis discussed above shows that the assumed trigonometric model
of installed capacity utilization in steam power plants gives results similar
to actual data.
Monthly average f. coefficients are nearly equal to 1. The additional
coefficient g. allows one to establish monthly average maximum coefficients
of installed clj^city utilization in steam power plants which will not be ex-
53
-------
TABLE 3.10. VALUES OF
No.
1
2
3
4
5
6
7
«" 8
9
10
11
12
13
14
15
16
Pro-
bab i -
"? (
80.0
82.0
85.0
86.0
87.0
88.0
89.0
90.0
91.0
92.0
93.0
94.0
95.0
96.0
97.0
50.0
Af.
rh
* a P
P)
1.28
1.34
1.44
1.48
1.51
1.55
1.60
1.64
1.70
1.75
1.81
1.88
1.96
2.05
2.17
0.674
Standard Deviation (cr)
(Jan)
0.119
0.152
0.159
0.171
0.176
0.181
0.186
0.190
0.196
0.202
0.208
0.215
0.224
0.233
0.244
0.258
0.080
(Feb)
0.124
0.159
0.166
0.178
0.183
0.168
0.193
0.198
0.205
0.211
0.217
0.224
0.233
0.243
0.254
0.264
0.083
(Mar)
0.109
0.139
0.146
0.157
0.161
0.164
0.169
0.174
0.179
0.189
0.191
0.197
0.205
0.214
0.223
0.236
0.073
(Apr)
0.098
0.125
0.131
0.141
0.145
0.148
0.152
0.157
0.161
0.167
0.171
0.177
0.184
0.192
0.201
0.213
0.066
(May)
0.127
0.162
0.170
0.183
0.188
0.192
0.197
0.203
0.208
0.216
0.222
0.230
0.239
0.249
0.260
0.275
0.085
(June)
0.139
0.178
0.186
0.200
0.206
0.210
0.215
0.222
0.228
0.236
0.243
0.251
0.261
0.272
0.285
0.302
0.094
(July)
0.117
0.150
0.157
0.168
0.173
0.177
0.181
0.187
0.192
0.199
0.205
0.212
0.220
0.229
0.240
0.254
0.079
(Aug)
0.113
0.145
0.151
0.163
0.167
0.171
0.175
0.181
0.185
0.192
0.198
0.204
0.212
0.221
0.232
0.245
0.076
(Sep)
0.095
0.122
0.127
0.137
0.141
0.143
0.147
0.152
0.156
0.161
0.166
0.172
0.179
0.186
0.195
0.206
0.064
(Oct)
0.090
0.115
0.120
0.129
0.133
0.136
0.139
0.144
0.147
0.153
0.157
0.163
0.168
0.176
0.184
0.195
0.060
(Nov)
0.094
0.120
0.126
0.135
0.139
0.142
0.146
0.150
0.154
0.160
0.165
0.170
0.177
0.184
0.193
0.204
0.063
(Dec)
0.099
0.127
0.133
0.143
0.147
0.150
0.153
0.158
0.162
0.168
0.173
0.179
0.186
0.194
0.203
0.215
0.067
-------
ceeded at a given probability. The probability given in this analysis was
determined for cases equal to and smaller than calculated, occurring once in
10 years. For example, in Table 3.11 monthly average coefficients in percent
of installed capacity for power plants of different full-load operating times
(T) and different probabilities are presented. These values were calculated
using equation 3.1.
3.4.4. BETA Distribution Model
In the BETA model, as with the cosine model of power plant operation, an
installed capacity utilization coefficient was assumed to be the ratio of
production to installed capacity. The installed capacity utilization coef-
ficient was assumed to be a random variable with a discrete time parameter,
considering power plant operation in monthly periods. Also, it was assumed
that the installed capacity utilization coefficients in a particular month are
independent variables, W., i= 1, 2, ... 12. Therefore, power plant load
determination is reduced to:
assumption of the probability distribution of the variables W.
where, 1=1,2,3,...
estimation of distribution coefficients,
distribution function tabulation for particular variables,
It was assumed that W. variables (1= 1, 2, ... 12) have a log-normal double
limited distribution. Minimum specification is zero and maximum specification
is 1 (100% installed capacity utilization).
A distribution which may be applied under such specifications is the
so-called BETA distribution iwth 0 and 100% specifications. The definition of
the density function of this distribution is:
f(x)= *P " ] O - w) q V 1 forO 0, q < 0) for w < 0 or w > 1 (3.19)
An estimation of the p and q parameters may be done using the moment method.
From equations:
(3.20)
CT2 = E9 (3.21)
W (p+q)2 (p+q+D2
After their conversion, the following equations are obtained:
55
-------
TABLE 3.11. MONTHLY AVERAGE INSTALLED UTILIZATION COEFFICIENTS, gimax (%), VARIOUS OPERATION TIMES, T/h/year
on
%
50
75
85
90
95
97
50
75
85
90
95
97
50
75
85
90
95
97
Jan.
61.327
66.283
71.290
73.469
75.761
77.310
72.996
78.894
85.604
87.447
90.175
92.019
84.465
91.290
99.054
101.187
104.344
106.447
Febr.
61.127
66.160
71.921
73.559
75.863
77.137
72.907
78.910
85.781
87.734
90.482
92.001
84.538
91.499
99.466
101.731
104.918
106.679
March
58.675
62.937
67.840
69.125
71.169
72.453
70.247
75.350
81.221
82.759
85.206
86.743
81.765
87.704
94.538
96.328
99.175
100.965
Apri 1
54.154
57.834
62.017
63.133
64.862
66.033
65.142
69.570
74.602
75.944
78.023
79.432
76.183
81.361
87.245
88.814
91.247
92.894
May
52.014
56.562
61.806
63.144
65.338
66.729
62.847
68. 343
74.680
76.296
78.947
80.628
73.822
80.278
87.721
89.620
92.734
94.708
T = 5000
June
52.365
57.271
62.805
64.267
66.564
68.130
T =
63.443
69.388
76.093
77.864
80.647
82.545
T = 7000
74. 721
81.724
89.621
91.707
94.985
97.220
h/year
July
52.155
56.279
60.925
62.178
64.110
65.415
6000 h/year
63.190
68.187
73.816
75.334
77.675
79.256
h/year
74.423
80.309
86.939
88.727
91.483
93.346
August
54.101
58.167
62.823
64.000
65.927
67.211
65.369
70.283
75.908
77.331
79.659
81.210
76.784
82.556
89.164
90.835
93.569
95.392
Sept.
56.440
60.009
64.081
65.140
66.814
67.929
67.893
72.187
77.084
78.359
80.371
81.713
79.399
84.421
90.448
91.639
93.993
95.562
Oct.
58.792
62.295
66.323
67.374
69.067
70.176
70.387
74.581
79.404
80.662
82.689
84.017
81.927
86.809
92.423
93.887
96.246
97.792
Nov.
61.430
65.251
69.617
70.769
72.588
73.801
73.268
77.825
83.032
84.407
86.577
88.023
84.957
90.241
96.279
97.873
100.389
102.066
Dec.
61.947
65.912
70.619
71.790
73.779
75.080
73.512
78.452
84.056
85.456
87.816
89.364
85.062
90.778
97.262
98.883
101.614
103.405
-------
w (w - w2 - o2 )
2 - — (3.22)
w
(1 - w) (w - w2 - a2 )
— (3.23)
w
where w and a2 are calculated on the basis of n-elements sequence of trials
W
as:
n
I w.
r. - 1=1
(3.24)
n
I (w. - w)2
2 - 1 = 1
CTwn(3.25)
Moreover, for the BETA distribution there is the following formula for model
value (distribution maximum density):
= . ] I P _ (3.26)
The distribution function is given by the equation:
p"1l-x)q"1dx (3.27)
V 0/xP-1(l-x)^1dx
F(x) = P(W
-------
3.5. Summary of Analysis of Monthly Installed Capacity
Utilization Coefficients
The analysis cover multi-unit power plants; that is, power plants equip-
ped with at least four units. The choice of models, as well as particular
calculations and values, refer only to Polish power plants operating in a
connected electrical power system. There was a lack of statistical data to
enable selection of a mathematical model for load changes in other electrical
systems.
Referring to the Polish electrical power system, there was also lack of
data describing installed capacity utilization coefficients in three-unit
plants. In the case of two-unit power plants, constant full load operation
is assumed for the purpose of cooling system design. In these power
plants, load changes are not systematic and can fluctuate widely.
The purpose of the analysis was to determine the maximum reliable in-
stalled capacity utilization coefficients which are the basis for open cycle
cooling system designs. These reliable coefficients are larger than the
average values for those power plants investigated.
The results of analysis using three compututional techniques are presented
in Table 3.12 and in Figure 3.3.
The results obtained from monthly modular coefficients of the BETA
distribution and the probable coefficients of the cosine model indicate good
agreement between them.
During summer months (June, July and August), the calculated coefficients
correspond to available capacity in compliance with the optimum repair sched-
ules. The agreement of the results obtained shows that the models correspond
to real conditions. For practical purposes, we propose the selection of the
cosine model and coefficients for power plant operation time of 6,000 h/year
with a 90% probability that the value will not be exceeded.
58
-------
TABLE 3.12. COMPARISION OF INSTALLED CAPACITY UTILIZATION MONTHLY
COEFFICIENTS OBTAINED BY DIFFERENT METHODS OF COMPUTATION
CJ»
ID
Month
Jan.
Febr.
••^•^•^^^•••WMMMM^^.^,
Mar.
Apr.
May
June
July
Aug.
Sept.
Oct.
Nov.
Dec.
Disposable capacity taking into
account repairs in power plants
with open cooling systems
100
100
100
100
93.2
75.4
73.3
74.8
94.4
100
100
100
Utilization of power plants
taken from computations
using the BETA distribution
Average
81.16
81.11
75.73
71.80
71.88
70.90
72.30
72.64
76.16
76.65
79.45
79.85
Mode
86.62
87.37
- mill niiaii I I ~ ill
80.04
74.34
74.36
74.34
75.34
75.74
80.19
81.36
85.11
85.94
Coefficient
T = 600 h
n ~ 90%
87.45
87.73
82.76
75.94
76.30
77.86
75.33
77.33
78.36
80.66
84.41
85.46
from cosine model
T = 6500 h
p = 75%
85.12
85.22
81.53
75.46
74.29
75.53
74.22
76.40
78.30
80.70
84.05
84.64
-------
£100
o
ol 90
Q.
^ 80
o> •—
o ~
60
C7>
fc 50
c
•s 40
-£ 30
20
10 +
o
1 - expected useable capacity in power plants with open cooling systems taking into account the
optimum repair schedule
2 - average actual capacity utilization in multiunit power plants
3 - mode of capacity utilization in operating multiunit power plants by BETA MODEL
4 -monthly coefficients of utilization for power plants with yearly operating time T = 6000h and
probability p = 90% (COSINE MODEL)
III
IV
VI
VII
VIII
IX
X
XI
XII
Fig.3.3. Comparison of real and calculated coefficients of installed capacity utilization in power plants in
Polish energetic systems
-------
4. Power Plant Capacity and its Relation to Temperature
Increases Downstream from the Discharge
4.1. Power Plant Capacity
From the standpoint of limiting temperature increases in the receiving
water, the capacity of a power plant operation with an open cooling system
can be determined by:
P*gki"Ck = Q-6ti-K.-p'C'3600 (4.1)
where:
P = power plant installed capacity, (MW),
g, . = monthly average coefficient of installed capacity utilization
under critical conditions (p=90%),
C. = waste heat discharged from the power plant in the cooling water
(Kcal/kWh),
c = specific heat of water, (kcal/kg/°C),
p = density of water, (kg/1),
Q = mean yearly river flow, (m3/s),
K. = distribution coefficient, describing the ratio of low monthly
flow (p=10%) to the mean yearly flow,
6t. = acceptable increase in mixed river temperature (assuming no
heat loss to the atmosphere) under critical conditions for
month i. Acording to the Section 2.6, the following values of
6t. are used for Polish rivers:
Jan - 6°C May - 6°C Sept - 5°C
Feb - 6°C June - 4°C Oct - 6°C
Mar - 6°C July - 4°C Nov - 6°C
Apr - 6°C Aug - 4°C Dec - 6°C
After transformation, equation 4.1 is as follows:
Q'K.'6t.-c«p
P= V 1 - - (4-2)
gki'Ck
For conventional power plants, C. is about 1200 kcal/kWh, which corresponds to
a thermal efficiency of ^ 34%; thtfs the above equation is as follows:
61
-------
Calculations of the capacities of power plants with open cycle cooling are
presented in Table 4.1. These data show that in most cases August is the
month when installed capacity should be limited. There are some cases, how-
ever, when capacity limitations occur in other months. For example, at the
Skawina Power Plant, the permissible minimum installed capacity is in Novem-
ber. This is because the regulation of permissible temperature increases in
the Vistula River downstream from the discharge limits the increase to 6°C
year round. Also, on the Danube and Dniester Rivers, capacity limitations
occur during the winter months. In particular cases, values close to the
August criterio noccur during the period from June through September. It is
worth noting that the calculation results are similar to the capacities of
power plants already constructed. A comparison of capacities calculated here
with capacities of operating power plants is presented below:
Cross- Permissible Capacity Power Installed
section Calculated for Plant Capacity
Critical Period (MW) (MW)
Vistula-Tyniec
Vistula-Szczucin
Vistula-Pulawy
Narew-Ostroleka
San-Radomysl
420-550
1260-1320
2300
550-600
450-490
Skawina
Pokaniec
Kozienice
Ostroleka
Stalowa-Wola
550
1000
2100
600
450
The Skawina power plant was built in the early 1950's with a combined
cooling system, and the calculations presented here confirm the correctness of
that decision. In the calculations for the Skawina power plant, a C. value of
1600 kcal/kWh was used on the basis of operating data. Calculations were also
conducted for the French power plant Vitry sur Seine. They show convergence
between results obtained by calculation and the installed capacity as in the
case of Polish power plants. Permissible calculated capacity for Vitry sur
Seine power plant ranges from 975 to 1100 MW, and the installed capacity for
this power plant is 1,000 MW.
4.2. Mixed Temperature Increases Downstream from Power Plants
Transforming equation 4.1, a formula describing completely mixed tempera-
ture increases downstream from the discharge under critical conditions, assum-
ing no heat loss to the atmosphere, is obtained:
62
-------
TABLE 4.1. CALCULATION OF INSTALLED CAPACITY WITH OPEN CYCLE COOLING IN POLISH RIVERS
o>
GO
Month
Jan.
Febr.
March
Apri 1
May
June
July
Aug.
Sept.
Oct.
Nov.
Dec.
gki
0.874
0.877
0.828
0.759
0.763
0.779
0.753
0.773
0.784
0.807
0.844
0.855
K.J Coefficients
Vistula-
Tyniec
0.38
0.37
0.82
0.66
0.47
0.35
0.38
0.35
0.29
0.33
0.29
0.36
Vistula-
Szczu-
cin
0.32
0.33
0.65
0.73
0.53
0.41
0.34
0.33
0.28
0.28
0.30
0.28
Vistula-
Pulawy
0.36
0.37
0.74
0.71
0.53
0.46
0.39
0.33
0.29
0.30
0.36
0.38
Narew-
Ostro-
leka
0.41
0.39
0.56
0.94
0.63
0.41
0.35
0.33
0.35
0.39
0.49
0.45
San-
Rado-
mysl
0.27
0.37
0.75
0.69
0.38
0.31
0.21
0.22
0.19
0.19
0.24
0.31
Vistula-
Tyniec*
533
518
1215
1065
750
551
619
551
490
499
420
518
Installed Capacity
Vistula-
Szczu-
cin
1615
1670
3800
4260
3080
1550
1340
1260
1320
1540
1570
1450
Vistula-
Pulawy
3340
3420
7340
7580
5630
3190
2800
2300
2500
3010
3450
3600
(MW)
Narew-
Ostro-
leka
900
860
1300
2380
1590
680
600
550
720
890
1120
1010
San-
Rado-
mysl
750
1020
2170
2210
1210
640
450
455
490
570
690
880
* For this cross-section a C. value of 1600 K cal/KWh was used to account for the combined cooling system
of the Skawina Power Plant.
-------
3600-Q-K^c-p
(4.4)
for average conditions:
(4.5)
3600-u.
where:
Q. =
average monthly long-term flow
median flows coefficients,
M50X
Qi 50%
monthly flow with a probability of p=50%
monthly coefficient of installed capacity utilization
under average conditions (p=50%),
Formula 4.5 can be simplified as:
360°'Qi50%-c'p
(4.6)
Calculated values for the Skawina power plant (Table 4.2) show good agreement
with measured values of heating for average conditions. But measured temp-
erature increases under critical conditions are up to 2.8°C lower than the
calculated values. This difference is probably due to atmospheric heat losses
and may be treated as a safety factor.
4.3. Discharge Design
Discharge designs are based on the biological premise that small areas of
thermal impact are more desirable than large areas. The impact of thermal
discharges on water temperature distribution was investigated on the Vistula
River below the Koiienice Power Plant and on the Narew River below the
Ostroleka Power Plant. In addition, laboratory investigations were conducted
using a hydraulic model.
4.3.1. Field Investigations
Some results of the field investigations are presented in Tables 4.3 and
4.4. For the purpose of these studies, the 0.1°C isotherm was used to delin-
eate the thermal plume. Data on plume width and capacity (i.e., % of river
flow in the plume) were then compiled. The value of % of river flow in the
plume is used as a measure of mixing.
64
-------
TABLE 4.2. THE COMPARISON OF CALCULATED vs. MEASURED TEMPERATURE INCREMENTS
IN THE VISTULA RIVER DOWNSTREAM FROM THE SKAWINA POWER PLANT
en
Month
Nov.
Dec.
Jan.
Febr.
March
Apri 1
May
June
July
Aug.
Sept.
Oct.
„<"
0.844
0.855
0.874
0.877
0.828
0.759
0.763
0.779
0.753
0.773
0.784
0.807
i
0.849
0.851
0.845
0.845
0.818
0.762
0.738
0.747
0.744
0.768
0.794
0.819
Km..
0.822
0.804
0.802
0.991
1.415
1.353
1.044
1.014
1.163
1.009
0.750
0.819
M<
0.804
0.849
0.879
0.889
0.481
0.936
0.876
0.744
0.796
0.851
0.779
0.740
Ki
0.29
0.36
0.38
0.37
0.82
0.66
0.47
0.35
0.38
0.35
0.29
0.33
Temperature
ment under
conditions
inc re-
average
Calcu- Measured
lated
3.36
3.36
3.12
2.58
1.58
1.61
2.17
2.65
2.17
2.93
3.66
3.63
3.31
2.90
3.72
2.44
1.68
1.61
2.07
1.99
2.06
2.60
3.50
3.49
Temperature
ment under
conditions
incre-
critical
Calcu- Measured
u lated
7.84
6.40
6.20
6.38
2.72
3.09
4.37
5.99
5.34
5.95
7.28
6.59
5.4
5.0
7.2
5.1
2.4
2.2
3.4
3.2
4.6
4.9
5.6
4.8
(1) For 6000 hrs/year at the 90% level.
(2) For 7000 hrs/year at the 50% level.
-------
TABLE 4.3. FIELD INVESTIGATION RESULTS IN THE VISTULA RIVER DOWNSTREAM FROM THE KOZIENICE POWER PLANT
CTl
Date Intake Distance
300 m
n&s
1 2
April 26-27, 1973 4.77
May 7-9, 1973 13.1
May 17-18, 1973 14.6
July 17-18, 1973 19.6
July 26-27, 1976 15.1
August 6-7, 1973 15.0
April 3-4, 1974 25.4
April 17-18, 1974 25.1
May 2-3, 1974 19.3
July 24-25, 1974 28.2
August 5-7, 1974 35.4
August 19-21, 1974 40.6
May 5-7, 1975 43.1
May 21-24, 1975 49.5
August 5-7, 1975 52.9
August 19-22, 1975 52.5
Sept. 2-5, 1975 53.4
Qp - cooling water flow m3/s,
p% Qc%
3 4
1.0 33
3.0 16
4.2 38
3.3 44
2.5 17
2.7 38
8.6 53
12.5 76
6.3 53
2.6 42
6.7 87
7.3 83
6.3
9.5 79
8.0 41
12.1 64
13.1 53
D B fo
5 6
99 25.3
50 12.7
122 31.1
105 26.9
102 33.3
106 28.3
105 19.9
148 47.4
130 41.8
140 28.0
180 67.4
235 60.2
-
140 54.4
109 25.7
97 51.3
95 38. 5
Distance
1000 m
Qo/ n
fo D
c c
7 8
34 160
40 75
64 115
21 90
40 140
24 150
71 216
82 220
75 188
30 172
90 380
80 365
74 250
55 223
45 190
87 339
63 210
B %
9
41.0
19.5
31.5
21.4
33.3
35.7
63.1
62.8
53.2
42.0
90.4
84.1
59.1
54.5
44.8
86.9
50.7
Qr%
10
34
32
90
50
52
84
69
45
90
76
92
58
(62)
-
-
(76)
(85)
Distance
9100 m
Bc
11
168
150
355
280
210
408
409
254
252
315
380
320
(395)
-
-
(363)
(273)
Distance
12.800 m
Bc%
12
38.0
26.3
75.5
53.5
41.6
71.9
77.9
71.7
54.7
62.2
76.3
64.2
(83.1)
-
-
(74.8)
(55.0)
Qo/ n
^ D
C C
13 14
-
-
-
-
59 260
77 305
92 490
50 252
53 256
-
88 360
77 260
1 00 449
90 382
70 233
100 416
84 386
ec%
15
-
-
-
-
58.4
69.6
98.0
55.3
63.7
-
81.8
59.8
100
85.4
52.0
100
85.6
Distance
35.500 m
QC Bc
16 17
-
-
-
-
-
-
-
100 400
66 245
53 207
91 335
55 380
100 393
100 390
100 392
100 396
100 364
Bc%
18
-
-
-
-
-
-
-
100
74.7
50.7
80.1
86.7
100
100
100
100
100
p - percent of river flow
Qc - per cent of thermal plume downstream
Bc - thermal plume width, m
Bc % - thermal plume width in
( ) - at a distance of 4,000
relation to
m
from the discharge as
river bed
width, %
per cent
of
total river
flow
-------
TABLE 4.4. FIELD INVESTIGATION RESULTS IN THE VISTULA RIVER
1000 m FROM THE DISCHARGE OF THE KOZIENICE POWER PLANT
Date
April 18, 1973
May 29, 1973
June 12, 1973
June 26, 1973
August 21, 1973
Nov. 16, 1973
Jan. 31, 1974
Febr. 21, 1974
March 14, 1974
May 29, 1974
July 12, 1974
Sept. 24, 1974
Oct. 10, 1974
Dec. 4, 1974
Dec. 19, 1974
April 9, 1975
June 3, 1975
June 17, 1975
Sept. 27, 1975
QP
(ms/s)
11.2
15.0
12.2
14.2
20.7
11.4
17-4
13.7
15.8
41.2
32.0
41.2
37.6
10.6
11.2
27.5
57.2
46.2
45.8
P
2.0
5.0
1.4
4.0
8.0
4.5
2.7
2.1
5.6
6.6
4.0
18.0
2.8
1.2
1-4
3.8
9.0
6.0
11.3
(m)
70
55
80
85
150
225
300
380
220
190
210
385
210
320
310
215
255
192
107
Bc
18
18
20
24
38
54
72
90
57
45
50
91
48
75
72
38
60
45
55
CO
29
29
28
34
47
49
75
85
49
28
29
95
25
68
67
46
63
50
62
67
-------
Investigations on the Narew River were carried out below the Ostroleka
Power Plant. At this location, a large river meander causes complete mixing
of the thermal plume. On the Vistula River investigations were conducted
below the Kozienice Power Plant. During the investigations, vertical tempera-
ture homogeneity at the distance of 300 m downstream from the discharge was
observed; further downstream some stratification occurred.
The results for the Vistula River show that the temperature distribution
downstream from the discharge is subject to random dynamic changes. Taking
into account the variability of the thermal plume distribution average values
obtained in particular cross-sections of the Vistula River were obtained:
Distance From the
Discharge (m)
300
1000
9100
12800
Flow Capacity
Q (%)
c
51.1
59.5
66.3
78.3
Width
Bc (m)
123
205
302
337
Width
B (%)
c
37.0
51.4
61.8
67.5
These average values show that with increasing distance from the discharge,
the thermal plume capacity and width increase. A comparison of average mixin
g coefficients (Q ,%) obtained in field investigations with those obtained in
laboratory tests (turopejskaja ... 1969) shows similar results.
Comparison of the results of field and laboratory investigations for an
average intake flow of 6.4% of the river flow is presented below:
Distance From Average Field Mixing Coeff.
the Discharge Mixing Coeff. From Lab. In-
(m) (%) vestigations
300
1,000
9,100
12,800
51.1
59.5
66.3
78.3
42.0
53.0
82.0
86.0
The project investigations show that particularly intensive mixing takes
place in the near-discharge field at a distance of 50 to 300 m downstream from
the discharge. Within this zone, the thermal plume capacity, Q , increased by
a factor of 8 and the maximum temperatures decreased 6°C. Theczone of inten-
68
-------
sive mixing is at the same distance (50 to 300) in the Vistula and Narew
Rivers (Figure 4.1).
Four winter surveys show that mixing intensity during the winter is
greater, but the number of investigations is too low to establish more specif-
ic relationships. Further field results are presented in Figures 4.2 and 4.3.
These figures show that after the zone of intensive mixing, cooling in the
river is slow, amounting to about 1°C in 35 km. This distance is confirmed by
previous studies (Gadkowski 1970), where, using Dobrowolski's results (1967),
it was shown that for similar intake percentages at the Stalowa Wola power
plant, total cooling distance under low river flows is 34 km and under average
flows about 86 km. Similar results have been obtained for the Lea River,
England (Gameson, et al. 1959) and Mikyska's elaboration (1964).
4.3.2. Model Investigations
Model investigations of heated waters discharged to free flowing rivers
were conducted at different values of the following elements:
distance from the intake to the discharge, L
angle of the discharge, ^
discharge channel width, b
A schematic of the model is presented in Figure 4.4.
Changes of particular elements were within the range of:
maximum distance L, up to 10B.
angle of the discharge p from /4 to /2,
discharge channel width b, from 0.3B to 0.7B, where B is the river
width.
The purpose of the studies was to describe the impact of the discharge
design on the thermal plume structure in the near-field and to establish the
analytical relationship describing plume axis development.
The investigations covered the range of geometric, dynamic and thermal
parameters at Polish steam power plant cooling systems. Intake flows in the
range of 10-100% of the river flow were used. Investigations of different
distances between the intake and discharge show that the location of the water
intake has a decisive impact on the velocity field between intake and dis-
charge. This impact is small at L=5B, but at L=l to 2B, which is common for
open cooling system design, this impact is very distinct. It is characterized
by irregular flow velocity distribution with decreased velocity at the bank
opposite the discharge and in some cases in a small area close to the dis-
charge.
The discharge angle has an important impact on the thermal plume struc-
ture (Figure 4.5) For a small discharge angle, the thermal plume is close to
69
-------
6t°C
16,0
15,0-
14.0
13,0
12,0
11,0-
a/ the average for 6 summer surveyrs in 1973
b/ the average for 13 summer surveyrs in 1974 and 1975
c/ the average for 12 summer surveyrs in 1973 -f-1975
d/ the winter surveyrs (6 surveyrs)
\
Vistula
(Kozienice power plant)
Vistula
(Kozienice power plant)
Narew
111X75. (OstroKeka power plant)
-I 1-
—I 1 1 I-"- I 1 1 H 1 (-»• | 1 1 1 —1 1 1 ^,
0,4 0,6 0,8 1pKm 0 0.2 04 0,6 Q8 1pKm 0 0,2 0,4 0,6 0,8 1,0 1,2 Km
Fig. 4.1. The maximum temperature decrease in the discharge zone below the Kozienice and Ostrofeka power plants
-------
a - the average for 6 surveyrs
b -the average for 13 surveyrs
o 2
26 28 30 32 34 36 distance from
the discharge km
Fig. 4.2. The maximum temperature decrease at a longer distance below the discharge from the
Kozienice power plant
-------
IS5
1 - the line of temperature drop caused by mixing
2 - the line of total temperature drop (mixing and surface heat exchange)
0
18 20 22
24 26 28 30 32 34 36 distance from
the discharge km
Fig.4.3. Average maximum temperature drop in the thermal plume below the Kozienice power plant
-------
Fig. 4.4. Scheme of model
73
-------
Fr0 = 2,0
0 0,25 0,5 0,75 1,0 1,25 1,5
0 0,25 0,5 0,75 1p 1,25 1,5
Fig.A.5. Arrangement of discharged jet axes with regard to changes
of outlet angle fB for b/B=0,5
74
-------
the discharge bank and the effect of the relative discharge value (Q /Q ) on
plume axis development is small. When the discharge angle is smaller tnan 67°
(n/2.67), the gradient of temperature decrease (6t/6L) drops and the distance
to the cross-section where the thermal plume covers the whole river width
increases. Changes of discharge channel width in the range of 0.3 to 0.7B
effect the thermal plume axis development by altering the discharge dynamics,
particularly when L > 28. The results of the investigation of different
angles of the discharge channels were analyzed using the least-square method.
Computation shows that plume axis position in the zone of free discharge may
be described by the function:
y = 0.272 x °'465 Fr0-°'159 p °'41 '(v^)'' (4.7)
in a rectangular co-ordinated system with the center situated on the axis of
the mouth of discharge channel and the x axis colinear with discharge bank.
Fr = discharge densimetric Froude number
3 = angle of the discharge,
v1 = average flow velocity in the river between the intake and
discharge,
v = average velocity in the discharge cross-section
The model investigations show that in order to keep horizontal stratifi-
cation in the river, the angle of the discharge channel should be in the range
of 45 to 65° in relation to the river axis, and discharge velocities should be
low in comparison with river flow velocities upstream from the discharge, v £
O.Sv1. z
o
75
-------
5. Combined Cooling Systems and Flow Augmentation
5.1. Review of Combined Cooling Systems and Flow Augmentation for Power
Plants
Combined cooling systems are designed for two purposes:
to enable power station operation in times of water shortage,
to regulate the discharge of waste heat to the receiving water.
The Blenod power station (Gras, et aJL 1969, 1971) (Figure 5.1) was one
of the first power stations to artificially augment low flows. This power
station has four units of 250 MW and was built in the period 1963-1969. Total
water demand for the cooling system of the Blenod power plant amounts to
40m3/s from the Moselle river. Annual mean flow in the river equals 130m3/s;
but in the mean year, flows smaller than 40m3/s occur for 158 days. Minimum
flows appear in September and October and, at p=10%, amount to 19m3/s. Much
smaller flows have been noted also, e.g. minimum 24-hour flows recorded in
1972 amounted to (EdF 1971, 1973):
9.0m3/s - in July
11.5m3/s - in August
4.3m3/s - in September
7.1m3/s - in October
Initially, water shortages were supplemented by recirculation of the
water discharged to the river, but this proved to be inefficient. Later,
water was taken from below the power plant and pumped through channels to the
Moselle above the power plant. The maximum discharge of pumped water was
30m3/s. This recirculation circuit is 100 hectares in surface area and, thus,
also provides a cooling function. In 1971, La Maxe power plant (two units of
250 MW power) was built (EdF 1973) 50 km below the Blenod power plant. A
precooling reservoir of 72 hectares (Figure 5.1) was built on the discharge
channel of La Maxe power plant to secure water temperature regulation. The
results of work on this reservoir are presented in Section 5.6 of this report.
Combined cooling to overcome water shortages was used at the nuclear
power plant of Neckerwesthein located on the Neckar River (Flinspach 1973).
This 900 MW power plant began operation in 1976; its water demand amounts to
40m3/s, while minimum flows in the Neckar River are about 20m3/s.
Combined cooling systems are being increasingly used to regulate dis-
charge temperatures. Many power plants utilizing this solution are under
operation in different countries. The 550 MW Polish power plant at Skawina,
built in 1957, is the oldest one. Other large power plants using combined
cooling circuits include the American power plants: Chesterfield, Dresden,
76
-------
*-•
the (a Maxe
power plant
- the measurement points
v discharge channel
preceding reservoir
The scheme of precooling reservoir of the la Maxe power plant
channel of forced recirculation of 4,lkrTL_fenqth
Moselle
recirculation
/pumping station
Q=30m3/s
Q
n
recirculation
The scheme of recirculation in the Blenod power plant
Fig .5.1.
French power plant cooling systems
77
-------
Monticello, Allen S. King, Browns Ferry and others; and West German power
plants: Biblis, Neckarwesthein, Grundrenmingen and others. The majority of
these plants utilize mechanical draft cooling towers for thermal energy dissi-
pation, but other solutions could include:
natural draft cooling towers,
spray equipment,
discharge channels and cooling ponds.
5.2. Assumptions Used in Analyses.
Taking into consideration solutions utilized in practice and results of
studies, combined cooling circuits can be divided into three categories:
parallel,
hybrid,
combined parallel/hybrid.
Parallel circuits employ cooling devices for a portion of total cooling
waterflow and cool it in a closed loop. Such parallel circuits are normally
used to overcome water shortages. Cost is the decisive factor in the selec-
tion of parallel circuits.
Hybrid circuits use cooling devices for the cooling water flow prior to
discharge, but the open cycle is maintained. Hybrid circuits are usually used
to maintain temperature conditions in the receiving water. Economical aspects
and efficiency of thermal energy dissipation are decisive factors in the
selection of hybrid technologies. The remainder of this analysis, is a dis-
cussion of hybrid technologies.
5.3. Determination of Hybrid Circuit Capacities
Using equation 4.1 it should be noted that alterations of power output
during a year depend upon the mutual relationships between:
admissible temperature increase, 6t.,
distribution coefficients, K.
coefficients of power utilization, g.
This dependency can be defined as:
6t.-K
P = f 1—! (5.1)
yi
or P - f (m) (5.2)
78
-------
where: 6t.-K.
m =
The "m" expression is called the coefficient of open circuit variation.
"m" coefficients for selected rover cross-sections are presented in Table 5.1
These results indicate that:
in the majority of cases, the month of August is the critical period
from the point of view of power plants with open cycle cooling
systems,
the value of the "m" coefficient depends on character of the river.
In the cases investigated, minimum "m" coefficients range between
0.67 for the Loire River and 2.62 for the Danube,
based on "m" coefficient values, the rivers can be divided into 3
groups:
a) rivers characterized by low "m" coefficients within the limits
of 0.67 to 1.12, including the Loire, Seine, San and Dniester
Rivers.
b) rivers characterized by "m" coefficients within the limits of
1.71 to 2.12, including the Vistula, Oder, Warta and Narew
Rivers.
c) rivers characterized by high "m" coefficients exceeding 2.6,
represented by the Danube.
In addition, Table 5.1 indicates that a high stability of the "m" coefficient
occurs along the Vistula River.
Another important factor is the "m" coefficient variation during the
year. Based on the rivers investigated, it can be shown that variations of
"m" can proceed in a rapid, medium or slow manner. Rapid variations of "m"
take place in the Loire River. On this river, if an increase in cooling
system capacity is needed, hybrid circuits can be employed for relatively
short periods of time, e.g., only 3 months, if we want to increase total
cooling capacity about 70% (e.g., for "m" coefficient ranging from 0.67 to
1.11). Slow variations of "m" appear in the Vistula at Szczucin. In this
case, employment of hybrid circuits to dissipate an additional 30% ("m" coef-
ficient ranges from 1.71 to 2.26) of the waste heat are required for 8 months
of the year. A medium example case is the Warta at Gorzow, where an addi-
tional 60% of the waste heat has to be dissipated during a 4 month period ("m"
from 2.12 to 3.35) and 90% of the waste heat has to be dissipated for 7 months
of the year. Data on the % cooling vs. time of cooling are contained in Table
5.2.
79
-------
TABLE 5.1. COEFFICIENT OF OPEN COOLING SYSTEM VARIATION, m
oo
o
— - — —
Vistula
Jan.
Febr.
March
April
May
June
July
August
Sept.
Oct.
Nov.
Dec.
Tyniec
2.61
2.53
5.94
5.21
3.70
1.80
2.02
1.81
1.85
2.45
2.06
2.53
Szczucin
2.20
2.26
4.71
5.77
4.17
2.10
1.81
1.71
1.78
2.08
2.13
1.96
Palawy
2.26.
2.53
5.36
5.61
4.17
2.36
2.07
1.71
1.85
2.23
2.56
2.67
Plock
2.88
2.80
6.01
7.82
4.64
2.10
2.12
1.81
2.10
2.45
2.70
2.80
Oder
Slubice
3.23
3.42
5.43
6.25
5.19
1.95
2.12
1.91
2.04
2.53
3.06
3.02
Warta
Gorzow
3.98
3.97
6.30
6.72
4.95
2.26
2.18
2.12
2.74
3.35
3.48
4.14
— •
Narew
Ostro-
leka
2.81
2.67
4.06
7.43
4.95
2.10
1.86
1.71
2.23
2.90
3.48
3.15
—
San
Radomysl
1.85
2.53
5.43
5.45
3.00
1.59
1.12
1.14
1.21
1.41
1.71
2.17
,.
Seine
Paris
3.98
3.97
4.85
3.48
2.67
1.33
1.06
0.88
0.96
1.04
1.07
1.75
-
Loire
Mont-
jean
4.32
4.99
4.42
3.71
2.44
1.44
0.96
0.67
0.83
1.11
1.78
3.02
Danube
Buda-
pest
3.50
4.04
4.78
6.82
7.39
4.63
4.25
3.62
3.63
3.16
2.90
2.62
Dnie-
ster
Zalesz-
czyki
1.03
1.37
.4.49
5.72
2.97
1.54
1.51
1.40
1.19
1.46
1.59
1.47
-------
TABLE 5.2. DEPENDENCE OF HYBRID COOLING SYSTEM OPERATION TIME ON HYBRID
CIRCUIT SIZE (in % of Open Cooling System Size)
oo
Hybrid Circuit Size (%)
Hybrid Cooling
System Operation
Time
(months)
1
2
3
4
5
6
7
8
Vistula
Tyniec
—
--
15
15
40
40
40
40
Szczu-
cin
__
—
15
25
25
25
30
30
Palawy
10
20
30
30
40
50
50
50
Plock
15
15
15
35
40
55
55
55
Oder
Slu-
bice
—
10
10
30
60
60
70
80
Warta
Gorzdw
--
10
30
60
60
90
90
90
Narew
Ostro-
leka
10
20
30
60
60
70
80
100
San
Rado-
mysl
—
10
30
40
50
70
90
Seine Loire
Paris Mont-
jean
10 20
20 40
20 70
20
50
100
Danube
Buda-
pest
10
20
30
40
40
50
60
80
Dnie-
ster
Zalesz
czyki
15
30
40
40
40
50
50
50
-------
5.4. Economic Aspects of Combined Cooling Circuits
Costs of combined cooling circuits have been compared with marginal costs
for open cooling circuits (in Poland) (Gadkowski 1972b). Marginal costs were
calculated by considering investment costs and operating costs of open and
closed circuits. Equation 5.3 allows one to define the economically justified
costs that can be paid for the open cooling circuit together with the equip-
ment for combined cooling, so that the total costs of a closed cycle circuit
shall not be exceeded.
/ bz-r \
Iz 11 + 2 J+ T-AK
Igr = ^ ^ 1 (5.3)
where:
Igr = marginal cost for combined cooling circuit (zl*/kW),
Iz = mean capital cost for closed cycle cooling circuit (zl/kW),
AK = difference between mean operating costs (depreciation excluded)
z of closed and open cooling circuits (zl/kW),
T = period of recoupment of capital cost (12.5 years for Poland),
bz = mean time of power plant construction with closed cycle cooling
circuit (assumed 5 years in Poland),
bo = mean time of power plant construction with open cycle cooling
circuit (assumed 6 years in Poland), and
r = interest rate (8%).
Based on cost indicators for Polish price levels of 1965, Gadkowski
(1972b) calculated: Iz = 410 zl/kW, AK =30.5zl/kW.
Calculations for combined cooling, not considering increase of fuel
prices, gives:
Igr = 704 zl/kW - this equals 16.0% of total power plant capital cost.
For open cycle cooling circuits, this cost indicator amounts to 5.1%; thus
16.0 - 5.1 = 10.9% is a marginal indicator of additional equipment for com-
bined cooling circuits. In current prices, this indicator (10.9%) amounts to
about 1,100 zl/kW of installed capacity.
zl = zloty, the unit of currency in Poland.
82
-------
Analyses on the following aspects were carried out:
increase of open cycle cooling possibilities by augmentation of low
flows,
cooling in discharge channels and reservoirs,
utilization of mechanical draft cooling towers.
5.5 Increase of Open Cycle Cooling Possibilities by Augmentation of Low Flows
Regulation of low flows by releases from upstream reservoirs is fre-
quently utilized in water management practices on many rivers. In some cases,
such low flow augmentation allows significant increases in natural low flows.
The Willamette River in the USA and the Seine River in France are examples of
successful low flow augmentation programs.
Utilizing methods described in Chapters 1 and 4, the economic aspects of
cooling capability increases in the Pulawy cross-section of the Vistula River
were analyzed based on augmentation of low flows. Assuming K=0.35; 0.40;
0.45, the flow shortages and increase of reservoir flows are presented in
Table 5.3. The calculated marginal benefits due to the increase in open cycle
cooling for power plants were compared with the capital costs of reservoir
storage and with the social costs of increased water flows. Capital costs of
storage were calculated based on the reduction of total capital costs of
reservoir and hydraulic construction, as well as the costs of flood control.
It was assumed that flood control occurred over 4 months; in the remain-
ing 8 months, the whole usable reservoir capacity is utilized for low flow
augmentation.
Investment costs of augmentation capacity (I ) were calculated according
to the equation:
Iw _ Ig x 8 + Uw x Ig x 4 _ Ig (2 + Uw) ^ ^
12 3
where:
Ig = capital cost of reservoir construction,
Uw = share of augmentation capacity of the usable capacity, %.
Based on economic indicators accepted by Hydroprojekt in the "Vistula"
Plan and comparing cost indicators with price levels from 1976, the indicators
of investment cost obtained on storage of disposable resources amounts to 11.5
zl/m3.
In Poland, social costs of flow increases are based on operating costs
and on the cost of capital (Ministerztwo 1975). The purpose of the interest
cost is to encourage rational water use. Social costs of water flow increase,
Ko, amount to:
83
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TABLE 5.3. COOLING SYSTEM PARAMETERS IN RELATION TO RATE OF FLOW
AUGMENTATION IN THE PULAWY CROSS-SECTION
00
Rate of flow
augmentation
0.35
0.40
0.45
Increment of Total
operating operating
Increment of time of open time of open
Flow shortages, cooling system cooling sys- cooling sys-
106 m3 % tern, months tern, months
156 611
300 21 2 3
450 36 4 6
-• —
Capacity Marginal costs
increment of increment
in power of open cooling
plant MW system size,
106 zl
138 151.8
483 531 . 3
828 910.8
-
Table 5.4. ECONOMICS OF COOLING SYSTEM SIZE FLOW AUGMENTATION
IN THE PULAWY CROSS-SECTION
Rate of flow
augmentation
0.35
0.40
0.45
Marginal costs of increment Investment costs of
of open cooling system size, water storage,
106 zl 106 zl
151.8 1794
531.3 3450
910.8 5175
Social costs of flow
increment,
106 zl
187.2
360.0
540.0
-------
Ko = _ (5.5)
L
where:
Ke = reservoir operating cost,
Iw = as in equation 5.4,
L = period of reservoir utilization (assumed L=100 years).
Individual social costs of flow increase in 1976 prices are 1. 2 zl/m3.
The comparative cost summary presented in Table 5.4 indicates that the
social costs of flow increase, are smaller than the marginal costs of open
cycle cooling increase. Investment costs of storage are too high to justify
reservoir construction only for the demand of power plant cooling. The calcu-
lations indicate that for construction of reservoirs for complex regulation of
low flows, a proper share of power plant output should be recognized as a form
of compensation for increases in river cooling capability. On the investi-
gated sections of the upper and middle Vistula, an increase of flow can be
utilized by the following four power plants:
Opatowiec - in area of the Danajec tributary,
Polaniec - below the Nida tributary,
Zamosc - below the San tributary,
Pulawy - above the Wieprz tributary.
5.6. Cooling in Discharge Channels and Preceding Reservoirs
Preceding reservoirs can be used as supplemental cooling facilities for
once-through plants or those using the surfaces of natural lakes or artificial
reservoirs for cooling. Under some conditions, the precooling reservoirs can
be combined with discharge channels and/or with artificial spawning channels
to reduce overall costs.
Examples of supplemental cooling systems include the following:
(1) At the Dresden power plant in the USA (Units 2 and 3 - 2x809 MW),
discharge channels with cooling sprays provide supplementary cooling
for an artificial cooling reservoir.
(2) At the Chesterfield power plant in the USA (Units 4, 5 and 6 with a
capacity 972 MW), water is discharged to an old riverbed of the
James River (channel Farrar Gut of 6 km length) (Jensen 1974);
supplemental spray cooling is also employed.
(3) La Maxe power plant - 2 x 250 MW (France), discharges water to the
Moselle River via a reservoir of 72 hectares. This precooling
85
-------
reservoir is 3,245 m long, with a maximum width of 350 m and a mean
depth of 1.60 m. The time of water flow through the reservoir is 12
hours.
A precooling reservoir of 73 hectares and depth of 2 to 3.5 m was built
for cooling system of the Patnow and Konin power plants in Poland. The basic
cooling system of these power plants is a complex of 5 natural lakes. The
precooling reservoir is supplementary to the circuit for two additional units
of 2 x 200 MW capacity- The water from the precooling reservoir is discharged
to a complex of fishing lakes of 185 hectares. This solution secured proper
cooling for the power plants and simultaneous utilization of heat release for
beneficial purposes (i.e. fishing).
Areas of precooling reservoirs can be defined by:
A_
w 6t
F = * (5.6)
where:
F = cooling area surface
A = thermal energy dissipation by the precooling reservoir
w = coefficient of surface heat exchange
6t = difference between the mean temperature in the precooling
reservoir and natural water temperature, (°C)
Assuming that:
natural temperature is 25°C (t )
temperature rise in the condenser is 8°C
amount of heat discharged to the cooling system, C. = 1200 kcal/kWh
K
coefficient of surface heat exchange according to the results of
research at the Konin lakes and Rybnik reservoir (Gadkowski 1976b):
w = 16.2 + 0.2-tn kcal/m2/h/°C (5.7)
The solution of equations 5.6 and 5.7 for various values of t provides the
following results for the precooling reservoir: n
Comparison of results for the La Maxe reservoir calculated according to
equation 5.7 (Figure 5.2.) indicates that intensity of surface heat exchange
in the La Maxe reservoir is, in the summer period, about 15% higher than in
the reservoir circuits in the complex of Konin Lakes and in the Rybnik reser-
voir. This difference can be explained by climatic and regional differences.
86
-------
00
surface
coefficient
Fm2/kW
for summer period
of the la Maxe
power plant
(7)- points for winter perioc
0
50
60
70
80
—I 1 •
90 100
heat losses %
Fig.5.2. Heat losses in preceding reservoirs
-------
Temperature drop through
precooling reservoir, °C
Heat dissipated, %
Cooling surface, sq. m/kW
Investment cost, % of
power plant construction
1 2 3
12.5 25.0 37.5
0.94 2.02 3.26
1.15 2.46 3.48
4
50.0
4.72
5.76
5
62.5
6.43
7.84
A detailed analysis of the preliminary cooling system for the Patnow II
power plant was conducted, including field measurements in the discharge
channel of Patnow power plant (Figure 5.3).
Five measurement cross-sections were placed on this channed:
point A - situated 100 m below power plant outfall,
point B - situated 150 m above first overflow to Goslawskie Lake,
point C - 200 m below last overflow,
point D - 580 m downstream from point C,
point E - about 100 m above the connection of the Konin power plant
discharge channel with the Patnow power plant discharge
channel.
The research was carried out in two annual measurement surveys in 1975
and 1976.
In 1975 the research included temperature measurements from boats. Six
measurement series were executed in this period; their results are presented
in Figure 5.4.
Lack of consistent cooling is observed for the overflow to Goskawski Lake
(i.e., between section B and C). It can be assumed that this phenomenon ap-
pears due to turbulent water overflow to the lake which causes intensive
evaporation and convective heat exchange between the water and atmosphere.
The results obtained during the 1975 surveys indicate that cooling on the
whole length of the channel, excluding the B-C section, is linear in charac-
ter. This permitted measurements made in 1976 over a short section to repre-
sent the whole channel length. Therefore, further measurements were made only
on the A-B section but with an increased number of samples.
In December 1975, four thermistor instruments were installed in cross-
sections A and B and in an additional cross-section, A' situated at a distance
88
-------
mean depth h = 3,1m
Width=32,5m
h=3,1m
width = 32,5m
L=960m
00
ID
the Pqtndw power plant
Fig. 53.
power plant
The distribution of measurement points in the discharge channel
of the Pqtnow power plant
-------
at air temperature tp > 20°C
3,0
C D
4,0 L(km)
E
at air temperature tp =10T20°C
3,0
4,0 L (km)
o
at air temperature tp<10°C
A
Fig
4,0 L(km)
CD E
51 Water cooling in the discharge channel of the Pqtnow power plant
- surveys in 1975
90
-------
of 690 m from cross-section A. At points A and A1, the detectors were in-
stalled at the surface, at mid-depth and at the bottom in 3 plumb lines, 1
detector each, for a total of 9 thermistors. At point B, a total of six
detectors were installed in two plumb-lines.
The measurements of 1976 were executed three times in a 24-hour period.
Because of power plant load alterations, some measurements were discarded.
Only result;- obtained at stabilized power plant power outputs were accepted
for analysis.
About 288 measurements were used in the subsequent data analysis. The
mean values of the results indicate that in the case of the Patnow power
plant, with a mean channel width of 150 m and a mean depth of about 3.0 m, the
intensity of water cooling in the channel may be described using the equation
5.8:
6t = e(a tn + b) (5.8)
where:
6t = indicator of water cooling at the distance of 1 km of the
channel reduced to the difference of 1°C between temperature of
discharge water and natural water temperature,
tn = natural water temperature, °C,
a,b = coefficients
a = 0.0235
b = 3.0713
The correlation coefficient of the curve obtained from the equation is
low and equals 0.31. The distribution of measurement points and the fitted
curve are presented in Figure 5.5 and show the large variability of the water
cooling effect in the channel.
Assuming a water temperature increase in the power plant of 8°C, it is
possible to describe the water cooling intensity as (6t):
at tn = 20°C, 6t = 0.232 °C/lkm
th = 25°C, 6t = 0.208 °C/lkm
Therefore under summer conditions, a distance of 4.5 to 5.0 km of channel
length is required for a 1°C drop in temperature.
Unit costs for 1 km of the discharge channel, by analogy to the Dolna
Odra power plant, may be assumed to be 0.26% of total investment costs. The
cost of the discharge channel necessary to cool the water by 1°C will thus
range from 1.17 to 1.3%. It is worth noting that costs of the discharge
channel as well as the costs of preceding reservoirs can vary widely depend-
ing on local conditions and methods of construction.
91
-------
(St°C/1km/°C
0,10
ro
00
O 00 O Q0 O
O O O
°oo ° ° *
i — i — i — i — i — i — i— i — i — i — i
i — i — i — i — i — i — I — i — i
1 234 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 tn °C
Fig. 55. Indicator of water cooling in the discharge channel of the Pqtnow power plant t°C/1km/°c
-------
5.7. Utilization of Mechanical Draft Cooling Towers
Utilization of mechanical draft cooling towers in hybrid installations of
combined cooling circuits is a recognized solution. It derives from both
economic and thermal aspects.
The thermal balance of hybrid circuits using cooling towers can be de-
fined as:
tn + At - AtH - aH = ap (5.9)
where:
tn = intake water temperature,
At - temperature rise in the condenser,
AtH = cooling range, difference between intake temperature and dis-
charge temperature from the cooling tower (in the majority of
hybrid cases, At., < At),
a,, = approach - difference between the discharge water temperature
and the wet bulb temperature,
a = wet bulb temperature.
P
As calculations indicate (Gadkowski 1972a), a significant role is played by
the approach in determining the costs and size of the cooling tower. In
general, the larger the approach, the smaller the cooling tower. Normally,
approaches less than 3°C are not designed.
In an earlier paper (Gadkowski 1969), a proposal for hybrid installations
using mechanical draft cooling towers was suggested as follows:
tn + 2At - Atu - a' = a (5.10)
H H p
a^ = aH + At (5.11)
A modified scheme for hybrid installations involves a two-fold tempera-
ture rise of the cooling water through the condenser. In this way a signifi-
cant increase of approach is obtained. Calculations indicate that this modi-
fied scheme of hybrid installations allows a decrease by nearly half of the
costs of mechanical draft cooling towers in Poland. Such a scheme is employed
in the cooling circuit of the Polaniec power plant, presently under construc-
tion.
93
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6. Summary
In this report, methods for determining capacities of open-cycle and
hybrid power plant cooling systems are presented. Hybrid cooling systems are
ones which combine once-through cooling systems with additional cooling de-
vices to reduce a part of waste heat load to obtain an acceptable temperature
increase in the receiving water.
The report provides detailed analyses of these main elements:
hydrological conditions required for once-through power plant cool-
ing systems,
guidelines, standards and regulations which are obligatory in vari-
ous countries,
water temperature and temperature increases downstream from the
discharges of existing power plants.
Based on the results of these analyses, it is concluded that once-through
cooling system capacity depends on:
hydrological characteristics of the river,
acceptable temperature increase downstream from discharge,
power plant capacity factor variability.
On the basis of various analyses of reliable flows for evaluating cooling
systems operating conditions, low monthly flows with a probability of occur-
rence p=90% are assumed reliable.
Analyses of water temperatures occurring downstream from the discharge of
power plants and the impact of heated water on the oxygen balance in the
receiving water as well as impact on fisheries were used to develop the fol-
lowing acceptable temperatures for Poland:
1. acceptable discharge water temperatures, 35°C
2. acceptable mixed temperatures downstream from the discharges, 30°C
3. acceptable temperature increase over the intake water temperature,
4°C to 6°C, depending on the season of the year.
To maintain the free migration of fish, discharge configurations which
guarantee a horizontally stratified temperature distribution in the receiving
94
-------
water downstream from the discharge should be applied. Model investigations
show that such horizontal stratification can be obtained when the angle of the
discharge channel is in the range of 45 to 65° in relation to the river axis
and when the discharge velocity is about half of the river flow velocity
upstream from the discharge.
Monthly average power plant capacity factor values are defined by:
g. = (f. + Af..) (b + 0.134 b cos,* - .008b2 cosa)
g.. = maximum monthly average capacity factor at the assumed prob-
ability of occurrence
b = annual mean capacity factor
f. = mean monthly correction coefficient
Af. = correction coefficient defining the relationship between the g.
1 value and the assumed probability level 1
a = angle designated by the function of a month:
21 - 1
or = - 7i
12
For practical purposes, coefficients for power plants with an operating time
of 6,000 h/year at a 90% probability were assumed. These values for indivi-
dual months and applied to power plants in Poland are listed below:
Jan. - 87.45 July - 75.33
Feb. - 87.73 Aug. - 77.33
Mar. - 82.76 Sep. - 78.36
Apr. - 75.94 Oct. - 80.66
May - 76.30 Nov. - 84.41
June - 77.86 Dec. - 85.46
From the standpoint of waste heat balance, the installed capacity of a
power plant with open cooling can be determined by:
where:
P = power plant installed capacity (MW)
g.. = monthly average capacity factor for p=90%
C. = waste heat discharged from the power plant in the cooling water
(Kcal/kWh)
c = specific heat of water (kcal/kg/°C)
95
-------
p = density of water (Kg/1)
Q = mean annual river flow (m3/s)
K. ,c = distribution coefficient, describing the ratio for low
1
monthly flow (p=10%) to the mean annual flow.
6t. = acceptable increase in mixed river temperature under critical
conditions for month i.
96
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7. Conclusions
As a result of the analyses conducted during this project, the following
conclusions are made:
1. Considering the variability in both river flow and steam power plant
load factors, the installed capacity of open cycle cooling systems in Poland
can be increased by about 25% without installation of supplemental cooling.
2. If the installed capacity of Polish power plants must be increased
by more than 25%, the best technical solution is hybrid cooling systems with
mechanical draft cooling towers and double-pass condensers.
3. For single power plants, modest increases in capacity (e.g., 20%)
over once-through systems can be economically obtained via open cycle systems
with pre-cooling reservoirs and spray systems.*
4. The economic analysis indicates that low flow augmentation using
upstream storage reservoirs is too expensive when used solely for stream
temperature control and can be applied only when a comprehensive water manage-
ment strategy is developed.
The author is aware of the difficulties encountered with spray system
operation in the USA. The use of spray systems in Poland would be predi-
cated on resolution of these operating problems.
97
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
REPORT NO.
EPA-600/3-79-Q72
3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
Evaluation of European Rivers for Power Plant Cooling
A Polish Research Project
5. REPORT DATE
July 1979 issuing date
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
Dr. Eng. Mieczslaw Gadkowski
8. PERFORMING ORGANIZATION REPORT NO
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Institute of Meteorology and Water Management
61 Podlesna Street
01-673 Warsaw, POLAND
10. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
PL 480 Project #PR-5-532-l4
12. SPONSORING AGENCY NAME AND ADDRESS
EPA/CERL
200 S.W. 35th Street
Corvallis, OR 97330
13. TYPE OF REPORT AND PERIOD COVERED
Final Report
14. SPONSORING AGENCY CODE
EPA/600/02
15. SUPPLEMENTARY NOTES
16. ABSTRACT
The report describes analytical, laboratory, and field research conducted to
optimize the use of rivers, specifically in Poland, for once-through cooling of steam
electric power plants. Maximum discharge and receiving water temperatures, based on
biological criteria, are coupled with natural flow and temperature variations to deter-
mine acceptable flow/temperature regimes for streams over an annual cycle. Control-
lable variables, such as repair schedules, reserve capacity, power plant size, hybrid
cooling system size and operation, and low flow augmentation via reservoirs, are evalu-
ated as mechanisms to modify electrical power output. The acceptable temperature/flow
regimes in streams are then compared to various power system configurations and sched-
ules to optimize the annual generation of electric power. Jhe following conclusions
are reached, relative to Polish conditions:
-- The installed capacity of open cycle cooling sytems can be increased by about 25%
without installing supplemental cooling.
-- For increases greater than 25%, mechanical draft cooling towers and double pass
condensers operated in a hybrid, open cycle is the most economical solution.
-- Low flow augmentation for power plant cooling via upstream reservoirs is economi-
cal only when used in a comprehensive water management plan.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
Thermal Pollution
Electric Power Plants
Cooling Systems
Poland
Hydrologic Analysis
07/B.C
8. DISTRIBUTION STATEMENT
Release Unlimited
19. SECURITY CLASS (ThisReport)
unclassified
21. NO. OF PAGES
112
20. SECURITY CLASS (Thispage)
unclassified
22. PRICE
EPA Form 2220-1 (Rev. 4-77) PREVIOUS EDITION \s OBSOLETE
102
&GPO 699-300
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