Environmental Protection Technology Series
FEASIBILITY STUDY FOR A
DIRECT, AIR-COOLED CONDENSATION SYSTEM
'*'
industrial Environmental Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Research Triangle Park, North Carolina 27711
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into five series. These five broad
categories were established to facilitate further development and application of
environmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The five series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
This report has been assigned to the ENVIRONMENTAL PROTECTION
TECHNOLOGY series. This series describes research performed to develop and
demonstrate instrumentation, equipment, and methodology to repair or prevent
environmental degradation from point and non-point sources of pollution. This
work provides the new or improved technology required for the control and
treatment of pollution sources to meet environmental quality standards.
EPA REVIEW NOTICE
This report has been reviewed by the U.S. Environmental
Protection Agency, and approved for publication. Approval
does not signify that the contents necessarily reflect the
views and policy of the Agency, nor does mention of trade
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recommendation for use.
This document is available to the public through the National Technical Informa-
tion Service. Springfield, Virginia 22161.
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'EPA-600/2-76-178
July 1976
FEASIBILITY STUDY
FOR A DIRECT, AIR-COOLED
1
CONDENSATION ,SYSTEM
by
Michael D. Henderson
R. W. Beck and Associates
400 Prudential Plaza
Denver, Colorado 80202
Grant No. R803207-01
ROAPNo. 21AZU-034
Program Element No. 1BB392
EPA Project Officer: James P. Chasse (EPA/Corvallis)
Industrial Environmental Research Laboratory
Office of Energy, Minerals, and Industry
Research Triangle Park, NC 27711
Prepared for
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Research and Development
Washington, DC 20460
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CONTENTS
Page No.
List of Figures iv
List of Tables V
Acknowledgments vi
Sections
I Conclusions 1
II Recommendations 2
III Introduction 3
IV Air-Cooled Condenser Systems 7
V Highlights of Site Visits 14
VI Prevention of Fintube Corrosion 42
VII Prevention of Coil Freezing 45
VIII Noise Attenuation 49
IX Application of Direct, Air-Cpoled Condensation
System in a Coastal Environment 50
References 59
Appendix 60
iii
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FIGURES
No. Page
1. GEA Air-Cooled Condenser Design Details 9
2. Lummus Air-Cooled Condenser Design Details 11
3. GEA Condenser at Albatross Refinery - Antwerp, Belgium 15
4. Discarded Aluminum Fins at Albatross Refinery - Antwerp,
Belgium 16
5. GEA Condenser at Condea Refinery - Brunsbuttelkoog,
West Germany 18
6. 10-Year Old Galvanized Fintubes at Condea Refinery -
Brunsbuttelkoog, West Germany 20
7. 2-Year Old Galvanized Fintubes at Condea Refinery -
Brunsbuttelkoog, West Germany 21
8. GEA Low Noise Condenser at Municipal Incinerator -
Zurich, Switzerland 22
9. Closeup of Acoustical Baffles at Municipal Incinerator -
Zurich, Switzerland 23
10. Lummus LATEC II Condenser at Linde Plant - Nuremburg,
West Germany 24
11. Lummus LATEC III Condenser at Voest-Alpine Steel Works -
Donawitz, Austria 26
i
12. Lummus Secondary Condenser Detail at Voest-Alpine Steel
Works - Donawitz, Austria 27
13. Lummus LATEC I Condenser at Nuovo Pignone Plant - Florence,
Italy 28
14. Lummus Low Noise Condenser at Chevron Refinery - Feluy,
Belgium ' 29
15. Natural-Draft Cooling Towers at C.E.G.B. Generating
Station - Rugeley, England 31
16. Example of the Oldest Epoxy - Coated Fintube Bundles at
C.E.G.B. Plant - Rugeley, England 32
17. GEA Condenser at Volkswagen Plant - Wolfsburg,
West Germany 33
iv
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FIGURES (cont)
No.
18. Aftercondenser on Oldest GEA Condenser at Volkswagen Plant -
Wolfsburg, West Germany 35
19. Natural-Draft Dry Tower at Preussag A.G. Generating Station -
Ibbenburen, West Germany 37
20. Fintube Bundles Subjected to Corrosion Analysis
at Preussag A.G. Generating Station - Ibbenburen, West
Germany 38
21. Cable Net Natural-Draft Dry Tower Under Construction -
Schmehausen, West Germany 39
22. GEA Condenser at Union Termica, S.A. Generating Station -
Utrillas, Spain 41
23. Types of Fintube Construction 44
TABLES
No. Page
1. Dry Cooling Tower Installations Visited by R. W. Beck
Personnel in 1973, 1974 and 1975. 4
2. Design Data for Direct, Air-Cooled Condensation Systems 52
3. Site Conditions for Direct, Air-Cooled Condensation Systems 54
4. Design Specifications for Direct, Air-Cooled Condensation
Systems 55
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ACKNOWLEDGEMENTS
The cooperation of C-E Lummus Heat Transfer Division and GEA
Airexchangers, Inc. is gratefully acknowledged for their assistance in
arranging the European itinerary.
Three other manufacturers of air-cooled heat exchangers have also
been of great help in documenting the experience of American manufac-
turers in this field. Special recognition is due to Hudson Products
Corporation, Ecodyne MRM Division and The Marley Company.
Personnel at the Neil Simpson Station of Black Hills Power and
Light Company and Rugeley Station "A" of the Central Electricity Gen-
erating Board were also gracious hosts to the research team.
Contributions from Battelle Pacific Northwest Laboratories and the
Aluminum Company of America have been of special value in preparing this
report.
J. P. Rossie, C. H. Armstrong and R. D. Mitchell have been asso-
ciated with numerous dry cooling tower studies performed by R. W. Beck
and Associates since 1969. Their editorial assistance has been inval-
uable. R. D. Mitchell was also responsible for the performance study of
the Braintree installation described in Section IX.
Vi
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SECTION I
CONCLUSIONS
The experience of owners of direct, air-cooled condensing systems
indicates that the systems are feasible. Three special areas of concern
were freezing during severe weather, corrosion in a marine or industrial
atmosphere and noise attenuation. The present investigation indicates
that:
1. Fintube bundle freezing can be prevented by proper system
design and strict attention to operating procedures.
2. The service life required of power plants can be achieved,
even in corrosive environments, by careful selection of fin-
type materials and manufacture of the cooling coils.
3. Special design considerations can attenuate dry tower fan noise
to meet very stringent requirements.
The performance of direct, air-cooled condensing systems can also
be optimized to minimize the cost of energy to consumers. In the particu-
lar case of an 85 MW combined-cycle unit being constructed for the
Braintree, Massachusetts Electric Light Department, the dry tower is
subject to only a minor cost (capital and bus-bar) penalty compared to
alternative cooling methods. A case-by-case analysis is necessary,
however, to determine the economic feasibility of direct, air-cooled
condensing systems.
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SECTION II
RECOMMENDATIONS
Based on the results of the present investigation, it is recom-
mended that a multi-year performance study of the dry cooling tower for
the 85 MW combined-cycle electric generating unit under construction by
the Braintree, Massachusetts Electric Light Department be undertaken
to substantiate the feasibility of this unit. The study should include
collection of tower thermal, meteorological and ambient air quality
data; fintube corrosion and noise surveys; laboratory analyses (for
particulates, salts, halogens, etc.); and studies of fluid distribution
within the cooling coils. Statistical analyses should then be used to
determine which parameters most influence the steam plant/air-cooled
condenser performance, and to determine the mode of operation required
for optimum performance.
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SECTION III
INTRODUCTION
The purpose of this report is to present the results of research
conducted by R. W. Beck and Associates to determine the feasibility of
utilizing air-cooled condensation systems in coastal environments.
Direct-cycle dry cooling towers transfer the heat of condensation of the
turbine exhaust steam directly to the atmosphere by means of air-cooled
heat exchangers, with no evaporation loss of circulating water. In this
respect, a major siting obstacle to the construction of thermal and
nuclear power stations is mitigated. Dry cooling towers are also bene-
ficial from the standpoint of environmental protection.
R. W. Beck and Associates is the consulting engineer to the Brain-
.tree, Massachusetts Electric Light Department for the design and construc-
tion of an 85 MW combined-cycle unit with associated dry cooling tower.
The exhaust heat from a 65 MW gas turbine will be utilized in an unfired
heat recovery boiler to produce steam for a 20 MW steam turbine.
Specific site considerations include subfreezing weather (down to a low
temperature of -22 C), a marine and industrial environment, and noise
attenuation required by the Commonwealth of Massachusetts to 51 dB(A)
within the plant boundary (400 feet from the dry tower).
Armstrong and Schermerhorn have recently studied this application
of a direct, air-cooled condensing system to a combined-cycle electric
generating unit. In this particular case, the dry tower is subject to
only a minor cost (capital and bus-bar) penalty compared to alternative
cooling methods. In addition, the use of a dry tower allows a signifi-
cant reduction in the total time required to complete the project (vis
a vis environmental issues associated with alternative cooling systems),
thus reducing indirect costs and partially offsetting the fuel cost
penalty. The study revealed the necessity of making a careful and
extensive analysis of how ambient air temperature will affect plant
performance characteristics and, in turn, fuel costs.
Major aspects of this study include selection of materials and fin
types to prevent external corrosion of fintube surfaces due to marine or
industrial environments, prevention of coil freezing during severe
weather and noise attenuation. Five manufacturers have been contacted
in order to ascertain the extent of their experience in providing this
equipment. On-site visits with owners and operators of dry towers have
also been made to determine whether the equipment can operate satisfac-
torily under a wide range of load and atmospheric conditions, and to
detail necessary maintenance procedures.. General information relative
to these visits is presented in Table 1. At many of these locations
corrosion and noise surveys were also conducted.
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Table 1. DRY. COOLING TOWER INSTALLATIONS VISITED BY R. W. BECK PERSONNEL
IN 1973, 1974, AND 1975
No.
1
2
3
4
5
6
7
8
9
10
11
Location
Wyodak, Wyo-
ming
Rotterdam,
Netherlands
Rotterdam,
Netherlands
Rotterdam,
Netherlands
Antwerp,
Belgium
Brunsbuttelkoog,
West Germany
Zurich, Switzer-
land
Nuremburg,
West Germany-
Green Springs,
Ohio
Baytown, Texas
Freeport, Texas
Owner
Black Hills
Power and Light
A. Z. C.
Zoutchemie
Esso
Refinery
Esso
Refinery
Albatross
Refinery
Condea
Refinery
Municipal
incinerator
Linde/air
separation plant
Columbia Gas
S. N. G. plant
Celanese
Chemical
Dow Chemical
/Designer
Service /Manufacturer
vacuum steam condensing
GEA
steam condensing
GEA
vacuum steam condensing
GEA
steam and hydrocarbon
condensing/Lummus
vacuum steam condensing
GEA
vacuum steam condensing
GEA
vacuum steam condensing
GEA
vacuum steam condensing
Lummus
vacuum steam condensing
Ecodyne MRM
steam ^condensing /Hudson
Products Corporation
hydrocarbon and vacuum-
steam condensing/Hudson
Year
Installed
1965
1969
1970
1970
1964
1967
1963
1971
1972
1972
1972
1971
1963
1971 .
Duty
(G cal/hr /MMBtu/hr)
5/20
40/160
.N/A
10/40
N/A
20/70
N/A
N/A
50/210
~~ 30/110
70/290
30/120
6/25
3/12
Date of
Visit
April,
1973
June,
1974
June,
1974
June ,
1974
June,
1974
June,
1974
June, 1974
July, 1975
June,
1974
August,
1974
August,
1974
August,
1974
Products Corporation
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Table 1. (Continued)
No.
12
13
14
15
16
17
18
19
20
21
22
23
24
Location
St. Croix, Virgin
Islands
Penuelas, Puerto
Rico
Donawitz,
Austria
Florence,
Italy
Nangis, France
Feluy, Belgium
Rugeley
England
Wolfsburg,
West Germany
Ibbenburen
West Germany
Schmehausen
West Germany
Utrillas
Spain
Nangis, France
Paris, France
Owner
Hess Refinery
Puerto Rico
Olefins
Voest- Alpine
Steel Works
Nuovo Pignone
manufacturing
plant
Grande Paroisse
C.D. F. Chemie
S. A. Chevron
Belgium N. V.
C.E.G.B.
Volkswagenwe rk
A. G.
Preussag A. G.
Hochtempe ratur
Kernkraftwerk
Union Termica
S. A.
S.E.I. F.
R. A.T.P.
Arber Station
/Designer
Se rvic e /Manufacture r
steam and hydrocarbon
condensing /Ecodyne
steam condensing
Marfab
vacuum. steam condensing
Lummus
vacuum steam condensing
Lummus
vacuum steam condensing
Lummus
vacuum steam condensing
Lummus
circulating water cooling
English Electric Co.
vacuum steam condensing
GEA
circulating •water cooling
GEA -Heller
circulating water cooling
Balcke-Durr GEA
vacuum steam condensing
GEA
vacuum steam condensing
Hudson Products Corp,
freon condensing
Hudson Products Corp.
- Year Duty Date of
Installed (G cal/hr /MMBtu/hr) Visit
1966
1971
1975
1967
1967
1975
1961
1961
1966
1972
1967
under con-
struction
1970
1967
1972
N/A
10/45
40/150
15/60
25/100
15/60
150/590
120/460
60/230
60/230
180/740
380/1500
275/1100
40/180
60/240
August,
1974
August,
1974
July,
1975
July.
1975
July,
1975
July,
1975
July,
1975
July,
1975
July,
1975
July,
1975
July,
1975
N.B. The numbers used to designate various installations in this table will be used throughout the report.
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Finally, a computer program has been developed to evaluate the
annual performance and bus-bar energy costs of the Braintree installa-
tion.
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SECTION IV
AIR-COOLED CONDENSER SYSTEMS
The familiarity of five different designers/manufacturers with the
production of air-cooled vacuum steam condensers has been determined
from their literature and discussions with engineering personnel. These
five are GEA Air exchangers, Inc., C-E Lummus Heat Transfer Division,
Hudson Products Corporation, Ecodyne MRM Division and The Marley Company.
The following paragraphs summarize the results of this investigation.
GEA is the parent company for several branches that design and
manufacture air coolers for various industries. The basic engineering
design for the Braintree dry tower was performed by personnel at the
home office in Bochum, West Germany. The actual contractual arrangement
however, was with GEA Airexchangers, Inc. , a U. S. corporation based
near St. Louis, Missouri. This company processed materials and sub-
assemblies from both domestic and foreign sources in conformance with
the engineering design generated in Bochum. GEA can document over 200
air-cooled vacuum steam condensers which are currently in service. The
oldest was installed in 1939. Although only a few of these units are as
large as the Braintree unit, they are all of basically the same design,
with improvements in structural components, fan-gear units and control
systems hardware in the newer models.
Lummus is a design engineering and construction firm owned by
Combustion Engineering, Inc., with engineering offices throughout the
world. The proposal for the Braintree dry tower was engineered by
personnel at the Heat' Transfer Division office in The Hague, The Nether-
lands and transmitted by Combustion Engineering's office in Windsor,
Connecticut. The Lummus LATEC (Lummusaire Turbine Exhaust Condenser)
design has evolved through three stages (designated .1, II and III), and
over 130 condensers are currently in service or under construction (earli-
est installation, 1962). The recent LATEC II and III designs (subsequent
to 1972) are similar with regard to heat transfer design concepts, the
basic difference between them being that the LATEC II configurations
have one overhead steam header, while LATEC III configurations have a
pair of fan-level headers.
Hudson Products Corporation, a subsidiary of J. Ray McDermott and
Company, Inc., is the largest U. S. manufacturer of air-cooled heat
exchangers, and, with its licensees in the United Kingdom, France, Italy,
Australia, Japan and Brazil have a similar position for process applica-
tions in the world. Hudson pioneered the design and manufacture of
AUTO-VARIABLE fans and large industrial wet-dry cooling towers, and
has had that equipment in extensive service for over 20 years. Hudson
designs and furnishes complete cooling systems for direct or indirect
steam condensing in natural or mechanical draft. Over 100 Hudson steam
condensers since as early as 1940 are in service, including over 25
vacuum steam condensers operating since 1961.
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MRM Division is the former McKinzie-Ris Manufacturing Company, now
owned by Ecodyne Corporation. MRM has manufactured finned tubing and
air-cooled heat exchanger assemblies for the past 40 years, and can
document more than 10 vacuum steam condensers in service since 196.4.
The Marley Cooling Tower Company, through its Dri-Tower Committee,
has studied various design and application problems associated with dry
cooling towers since early 1967. This Committee has held the opinion
that direct, air-cooled condensing systems for large power plants would
not be feasible in the foreseeable future, but that designs adopted from
the hydrocarbons and petrochemical industry could be used by utilities
for small steam units with only a slight additional concern for operat-
ing procedures. Marley, therefore, is concentrating on larger utility
applications with their Parallel-Path Wet-Dry Tower.
GENERAL DESCRIPTION OF AIR-COOLED
CONDENSER OPERATION
GEA, Lummus and Hudson Products Corporation offer dry-cooled vacuum
steam condensers which differ significantly in detail. However, since
their fintube bundle and mechanical equipment arrangements embody heat
transfer concepts which are representative of the designs offered by the
various manufacturers, their units will be described in detail.
GEA Air-Cooled Vacuum Steam Condenser
The GEA patent encompasses the use of elliptical finned tubes and a
series connection of parallel ane counterflow elements known as the
"condenser-dephlegmator" combination (see Figure 1). The steam duct
through which the turbine exhaust steam is transferred to the air-cooled
coils runs horizontal to the point of rising to the condenser inlet
headers. The condenser tube bundles are installed in A-type frames on
the condenser platform. Only the parallel flow bundles are directly
welded to the inlet steam header located on top of the bundles. The
steam enters these bundles and flows downward parallel with the con-
densate to the bottom condensate header which runs along the bottom
inside the A-type structure. The excess steam is carried through the
condensate header and flows upward, cduntercurrent to the condensate,
through the dephlegmator bundles. The noncondensible air is evacuated
from the top of the dephlegmator bundles. The dephlegmator bundles are
located toward the center of the unit to assure maximum symmetry in the
steam distribution. The hot condensate flows by gravity to the hot well
tank.
Each fan module encompasses tube bundles on each side of the A-
frame. Adjacent modules are separated by partition walls to avoid
evacuating air when a fan is "off". Doors are provided in the partition
walls to allow free access into the air plenum even while the fans are
in pperation. The fans are driven by horizontal two-speed motors via
worm gear speed reducers supported on the fan bridges.
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PARALLEL FLOW CONDENSER
STIAM
OF CONDENSATION
ZONE MOWS
ATHIOHLOAO:
8TCAM CXDMCTION
Q • k • F -At,
m
G,- Gr
DEAD ZONE = CONDENSATE
SUBCOOLING
i.e. a) RISK OF FREEZING UP AT
TA«»< 0°C
b) OXYGEN PICK-UP
I. RISK OF CORROSION
DANGER INCREASES WHEN COOLING
AIR FLOW IS REDUCED
COUNTER FLOW CONDENSER
(Dephlegmotor)
I. NO CONDENSATE SUBCOOLING
IF DESIGNED PROPERLY
2. POOR HEAT TRANSFER
COEFFICIENT
(TO SOME EXTENT)
CMC 4. EXCESSIVE LOAD OF
PIN AIR EVACUATION IF VERY HIGH
AIR TEMPS. ARE INVOLVED
COMMNMTI
STEAM
CONOENSATE
AIR
FIGURE I - OEA AIR-COOLED CONDENSER
DESIGN DETAILS
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A wind wall of the same height as the tube bundles is sometimes
used to prevent warm air recirculation, which may be a problem under
Strong wind conditions. The condenser platform is elevated above ground
and supported by a steel structure. The height of this structure is
chosen to assure an average air access velocity of not more than 5
meters per second (16.5 fps). This is necessary to achieve low air
inlet pressure loss and even air flow distribution.
The holding ejectors for condenser evacuation during normal oper-
ation are mounted on a platform on top of the condensate tank. A'
separate hogging ejector is used for startup operation.
Lummus Air-Cooled Vacuum Steam Condenser
The patented Lummusaire Turbine Exhaust Condenser (LATEC) design
illustrated in Figure 2 is based on a modular concept for ease of manu-
facture, control, maintenance and erection. The basic component of the
module is the tube bundle consisting of a number of finned U-tubes.
Each tube bundle includes a separate secondary condenser which removes
noncondensibles.
The bundles are supported by an "M" or "A" frame structure and are
arranged for co-current flow (from the inside to the outside of the tube
bundle) of air and steam. Several fintube bundles are combined in one
module and are served by one or more axial flow fans which supply air
under forced draft. Each fan is driven by an electric motor through a
gear box. Each bundle has its own inlet manifold and two outlet conden-
sate manifolds. The inlet manifold is connected to the main steam
manifold which feeds steam from the turbine exhaust through the main
steam line. The bundle condensate manifolds are connected to the main
condensate line going to a loop seal and into the condensate receiver.
The noncondensibles are removed from the secondary condenser of each
bundle through air take-off lines to the air ejector system.
The bundles are arranged such that the unfinned part of the U-tube,
i.e. the return bend, is located just on top of or underneath the steam
manifold of the adjacent bundle. This results in a plot space saving of
up to 25 percent over side-to-side designs without increased power
consumption.
Turbine exhaust steam flows through a minimum length exhaust line
which is connected to the distribution steam manifold serving the con-
denser. The condenser manifold provides steam distribution to the
individual bundle manifolds or headers. The steam flows from the header
manifold through the inlet legs of two rows of U-tubes. The axial flow
fans force atmospheric air across the tube rows. A portion of the steam
is condensed in the first two rows of tubes. The mixture of steam and
condensate then flows by gravity through the sloped U-bends and the
remainder of the steam is condensed in the second two rows. The cold
inlet air is heated as it passes through each successive row in co-
current flow with the hot fluid.
10
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TUOTINE EXHAUST LIME
HOT WELL
STEAM DISTRIBUTION LINE
ATMOSPHERIC RELIEF VALVE
HOGGING JET
STEAM MANIFOLD
PRIMARY CONDENSER
SECONDARY CONDENSER
CONDENSATE LIME
LOOP SEAL
DUMP VALVE
CONDENSATE TANK
AM TAKE-OFF LINE
EJECTORS AND INTER-/AFTEM-CONDENSCR
COM0EMSATE RETURN LINE
CONOENSATE PUMPS
CONOENSATE DISCHARGE FROM INTER/AFTER-CONDENSER
CONDENSATE RETURN LINE TO BOILER
CONOENSATE TANK LEVEL RETURN LINE
FIGURE 2 - LUMMUS AIR-COOLED CONDENSER DESIGN DETAILS
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The condensate from each of the two return legs is drained through
the separate condensate manifolds to the condensate line. Each con-
denser has a loop seal between the main condensate line and the conden-
sate receiver.
In each bundle, the noncondensibles and any uncondensed steam flow
into the separate condensate outlet manifolds and are further cooled in
the secondary condenser before entering the air ejector system. Thus
the maximum amount of steam is condensed before the noncondensibles are
evacuated.
Normally, separate forced draft fans provide cooling air for tube
bundles on each side of the "A" or "M" frame structure. Each cooling
module is separated from adjacent modules by internal partition walls.
Wind walls are an integral part of the "M" frame design and are
used, where necessary, with the "A" frame configuration to prevent
external warm air recirculation that may occur during strong wind con-
ditions.
Hudson Air-Cooled Vacuum Steam Condenser
Among the design features utilized by Hudson in vacuum steam
condensers, a number of which are patented, are:
Steam Side
Restrictive steam flow on a modular or row basis
Special two-pass design
Multiple tube diameter in succeeding tube rows
Vent condensers following main condenser in series
Dephlegmator (for vertical or drastically1 sloped tube designs)
following main condenser in series
Air Side
AUTO-VARIABLE Pitch Fans
Allows totally modulated automatic control
Saves power (compared to shutter or step-wise motor speed
control)
Permits reversal of air flow direction for winterized designs
Variable tube finned length in succeeding tube rows
Induced draft designs with internal air recirculation, utilizing
AUTO-VARIABLE pitch fans and wind skirts, or AUTO-VARIABLE pitch
fans and top mounted shutters
Forced draft designs with external air recirculation, utilizing
shutters for air inlet, air exit and air bypass, with or without
AUTO-VARIABLE pitch fans
12
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Hudson offers horizontally or vertically oriented bundles, "A" or "V"
designs, for ground or structure mounting.
As designers of the first industrial AUTO-VARIABLE fan in 1952, in
addition to a standard line of adjustable pitch fans (both in diameters
from 6 to 60 feet), Hudson has experience in modulation and direction
control of air flow for steam condenser control and in special fan
designs for low noise applications.
13
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SECTION V
HIGHLIGHTS OF SITE VISITS
In the course of visits to the 24 dry cooling tower installations
listed in Table 1, specific items of interest were investigated. Three
main areas of concern for this research project were prevention of ex-
ternal corrosion of fintubes in marine or industrial environments,
prevention of coil freezing during cold weather, and noise attenuation.
Additional highlights included examples of design development for both
the GEA and Lummus condensers, recent analysis of corrosion problems at
installations which have been visited previously by R. W. Beck and
Associates personnel, and development of a new concept in the structural
engineering of natural-draft towers. These visits are described below
in chronological order.
ALBATROSS REFINERY (5)*
This installation is located on the northeast edge of Antwerp,
Belgium along the canal which connects the city with the North Sea. The
GEA unit at this refinery condenses steam from a small turbine driving
an electric generator. Figure 3 is a photograph of this unit. The
corrosive effects of the salt and industrial pollutants in the atmosphere
at this location have taken their toll on various metals. All bare
steel is in very poor condition, and some aluminum fintubes in a process
cooler have failed. Frequent repainting has kept painted steel in good
condition, and galvanizing shows only a slight dulling.
Behind the power plant is a pile of discarded tubes from one of the
process coolers in this refinery. These tubes, which were made by
wrapping an L-shaped strip of aluminum around a steel tube, are commonly
referred to as the "L-fin" tube. They were removed from service because
the bottom row of fins became so corroded that cooler performance was
inadequate and the construction of the cooler required that the top
banks of tubes be cut away in order to remove the bottom row.
The aluminum fins on the tubes taken from the bottom row have
accumulated a coating of black, brown and reddish dirt. The edges of
the fins have been eaten away by corrosion, while cracks run from the
corroded areas toward the tube. Corrosion and cracking are worse on the
sides of the fins which were toward the incoming air stream. The fins
on tubes from the second row are in much better condition, although some
dirt buildup and light corrosion appear on the inlet air sides of these
tubes also. Figure 4 shows these corroded fins.
* Numbers in parentheses refer to identification numbers in Table 1.
14
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-
'-. .
• i •»»*
*
FIGURE 3 - GEA CONDENSER AT ALBATROSS REFINERY
ANTWERP, BELGIUM
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-
ALUMINUM "L-FOOT FIN FROM
ALBATROSS REFINERY -
ANTWERP, BELGIUM
FIN FROM 1st ROW OF TUBES
FIN FROM 2nd ROW OF TUBES
FIGURE 4 - DISCARDED ALUMINUM FINS AT ALBATROSS REFINERY
ANTWERP, BELGIUM
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Since the fins corroded only where dirt collected on them, some
pieces of these fins were analyzed by chemical methods to identify the
corrosive agent in the dirt. The analysis report indicated that soluble
salts (chlorides and sulfates) compounds in the air plus moisture cre-
ated an acid condition and, in conjunction with heavy metals, resulted
in .corrosion.
As fins were peeled from these tubes, it was observed that the
steel tube had been rusting underneath the foot of the fin. This rust
is present on all tubes, not just those which were located in the bottom
bank. This would indicate that moisture in the air had come into con-
tact with the steel tubes, quite possibly after their removal from
service.
CONDEA REFINERY (6)
The location of this installation is Brunsbuttelkoog, West Germany,
at the mouth of the Elbe River on the west end of the Kiel Canal con-
necting the North Sea with the Baltic. The GEA unit at this refinery
was installed in 1963 and enlarged in 1971 by the addition of some
fintube bundles. Thus it allows a comparison between the condition of a
relatively new unit with a unit that has been in operation for more than
10 years. Figure 5 is a photo of this condenser. The three bundles of
fintubes located on the left side of the unit and separated from the
other six bundles are the sections installed in 1971. Note that the
unit includes space on the left for the addition of yet another three
bundles.
The unit operates today under different criteria than those original-
ly used. When the new sections were added in 1971 to increase the con-
densing capacity, the overall performance parameters were changed to
allow lower turbine backpressure and better plant thermal efficiency.
Operating personnel indicated that since the new sections have been
added, the increase in heat transfer capability has resulted in a ten-
dency for the unit to begin freezing at -7 C (20 F) under low loads.
They cover some of the sections with tarpaulins during severe weather to
prevent this freezing.
The atmospheric conditions here that contribute to corrosion of
metals consist mainly of salt spray borne inland by winds. Salt col-
lects on the windward side of buildings and equipment where it is
allowed to remain until washed away by subsequent rains. Industrial-
type pollutants are reputed to be uncommon in this rural area. Bare
steel is badly rusted, while painted steel and galvanizing are in good
condition. A special alloy of aluminum containing some magnesium has
been used as lagging on pipe insulation and is in good condition, with
its oxidized surface intact. Aluminum-finned heat exchangers in the re-
finery give satisfactory service, according to operating personnel.
17
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FIGURE 5 - GEA CONDENSER AT CONDEA REFINERY
BRUNSBUTTELKOOG, WEST GERMANY
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Figures 6 and 7 compare the appearance of galvanized fintubes on
the old and new sections of the GEA condenser. The older fins are
darker in color than the new fins, but in quite good condition. Some of
the fins from the older section which have been bent and damaged to
expose the steel beneath are rusted where the galvanizing has been
removed, but have not suffered a significant reduction in heat transfer
capabilities.
ZURICH, SWITZERLAND MUNICIPAL INCINERATOR (7)
This GEA unit is connected to the steam turbines which generate
power at this incinerator. This unit is located inland in a relatively
pollution-free environment. The main reason for visiting this unit is
that it was designed for the extremely low noise level of 45 dB(A) at
120 meters (400 feet). Figure 8 is a photo of this condenser.
A number of methods were used to attain the low noise levels for
this unit: 1) large diameter fans were employed; 2) motors are slow-
speed units connected directly to the fan in order to eliminate a re-
duction drive gear with its attendant whine; and 3) the air inlet plenum
is totally enclosed on the two sides that allow air into the unit by a
set of acoustical baffles. Figure 9 is a closeup of these baffles from
inside the plenum chamber. The baffles, consisting of a fibrous material
sandwiched between plates of perforated metal, are about 15 cm (6 inches)
thick and spaced about 0.5 m (1.5 feet) apart.
The eight fans on this unit are approximately 6 m (20 feet) in
diameter and are powered by two-speed electric motor drives which oper-
ate the fans at either 136 or 68 revolutions per minute. Noise measure-
ments were made at the unit by the research team and are reported in
Section VIII.
LINDE AIR SEPARATION PLANT (8)
This unit is located in central West Germany, in a light-industrial
area near Nuremburg. The unit was manufactured to a design provided by
the Lummus Company and condenses steam from a turbine generator. It is
designated a LATEC II type by Lummus. The main difference between this
unit and the later LATEC III type is that it has a single upper header
(see Figure 10), while the steam header for the LATEC III runs along
each side of the bottom of the coils.
This condenser has experienced a single episode of freezing which
occurred during the first cold weather period of the season. Operating
personnel injected live steam into the condensate line as they thought
this would keep the condensate warm and thereby prevent freezing. In
fact, this had the effect of setting up a reverse-flow of condensate
back up into the finned tubes with subsequent freezing. It is a charac-
teristic of the LATEC bundle design that, if freezing does occur, as in
this rather unusual case, it will be confined to the V-bends which are
exposed and readily,accessible for repairs. Being circular in shape,
the finned section of the U-tube does not undergo deformation.
19
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o
•
FIGURE 6 - 10 YEAR OLD GALVANIZED FINTUBES AT CONDEA REFINERY
BRUNSBUTTELKOOG, WEST GERMANY
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ISJ
FIGURE 7-2 YEAR OLD GALVANIZED FINTUBES AT CONDEA REFINERY
BRUNSBUTTELKOOG, WEST GERMANY
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FIGURE 8 — GEA LOW-NOISE CONDENSER AT MUNICIPAL INCINERATOR
ZURICH, SWITZERLAND
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CLOSEUP OF ACOUSTICAL
BAFFl ES AT MUNICIPAL INCINERATOR
FIGURE
ZURICH, SWITZERLAND
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.
r
FIGURE 10 - LUMMUS LATEC H CONDENSER AT LINDE PLANT
NUREMBURG, WEST GERMANY
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Lutnmus used an infrared camera at this unit to examine the effect
of artificially-induced air leaks during operation; the areas near the
air leaks were cooler than the parts of the unit that were operating
properly. With this method, operating condensers can be examined to
investigate air recirculation and wind effects, steam maldistribution
and operation at partial loads.
VOEST-ALPINE STEEL WORKS (14)
This LATEC III unit, located in a mountain valley in the Austrian
village of Donawitz, condenses steam from a turbine generator. Its
design combines an especially steep angle of the tube bundles with a
system of overlapping the header ends of the bundles in order to save
ground area and to make the airflow distribution more efficient. These
concepts can be seen in Figure 11, and were quite important in the
selection of a condenser for this particular application because of
space limitation at the site. Details of the secondary condenser, located
at the lower end of the fintube bundle and upstream of the air evacuation
equipment, can be seen in Figure 12.
NUOVO PIGNONE PLANT (15)
This unit designated as a LATEC I, is located approximately 75 km
(45 miles) inland from the Ligurian Sea in a highly-urbanized area of
Florence, Italy, and was manufactured by Nuovo Pignone to a design
produced by the Lummus Company. The unit is used to condense steam
during the testing of turbines and compressors built by Nuovo Pignone at
this plant and for this reason has been subject to a cyclic variation of
its operational use and working temperature levels. This early LATEC
design is easily distinguished from later models by the use of nearly-
horizontal fintube bundles as shown in Figure 13. The unit is also of a
single-pass steam flow with aluminum G-fins, i.e., embedded into the
steel tube, in contrast to the double-pass U-tubes with aluminum L-fins
typical of later designs.
Even though traces of chloride ion were found in laboratory analy-
sis of a fin sample from this unit, the cooling coils were in very good
condition. The only noticeable corrosion was that of unpainted steel,
which has had no effect on its performance.
CHEVRON REFINERY (17)
This unit, located in a rural area approximately 30 km (20 miles)
south of Brussels, Belgium, was manufactured to a design provided by the
Lummus Company and condenses steam from a turbine pump drive used for
pumping refinery products through a product pipeline. Figure 14 is a
photo of this unit.
The unit was designed for a sound pressure level of 82 dB(A) at
1 m (3 feet) below the fans with four large diameter slow-speed fans.
The fans are single-speed (128 rpm)with automatic variable pitch blades
and bell-shaped inlet plenums. Noise measurements were taken at the
unit by the research team and are reported in Section VIII.
25
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FIGURE II - LUMMUS LATEC HI CONDENSER AT VOEST-ALPINE STEEL WORKS
DONAWITZ, AUSTRIA
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FIGURE 12-LUMMUS SECONDARY CONDENSER DETAIL AT VOEST-ALPINE STEELWORKS
DONAWITZ, AUSTRIA
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-
FIGURE 13 ~ LUMMUS LATEC I CONDENSER AT NUOVO PIGNONE PLANT
FLORENCE,ITALY
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-
FIGURE 14-LUMMUS LOW-NOISE CONDENSER AT CHEVRON REFINERY
FELUY, BELGIUM
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C.E.G.B. RUGELEY STATION "A" (18)
Located approximately 200 km (120 miles) northwest of London in a
rural coal-mining village, Rugeley Station has been the site of the
Central Electricity Generating Board's research into the feasibility of
dry cooling towers for power plant application since late 1961. A de-
scription of the indirect dry-type Heller system utilized with a natural-
draft tower has been prepared previously. Figure 15 is a photo of the
four natural-draft wet towers which serve Station "B" and the shorter,
wider-mouth dry tower which serves 120 MW "A" Unit 3. Station "A" is
comprised of five 120 MW units, and Station "B" has two 500 MW units.
" The principal reason for visiting this generating station was to
check on progress made in controlling external fintube corrosion since
an earlier visit in late 1969. Corrosion is thought to result from the
proximity of the coal mining/storage operation, an ash-sintering plant
(for the production of building materials), and the evaporative cross-
flow cooling towers. The coal mined at the site is relatively high
(0.6%) in chlorine content and probably contributed significantly to the
failure of the original aluminum (tube-collar-plate fin) Forgo coils.
All of these fintube bundles have been subsequently replaced.
A total of four sets of fintube bundles have been used in the
Rugeley dry tower. Only the original bundles were a complete set. The
latest three types (still in use), in chronological order, have been:
epoxy-coated Forgo elements (see Figure 16), an English Electric Company
scallop-edged plate fin design, and epoxy-coated Forgo elements. In
conjunction with this test program on various fintube constructions, a
new repair technique involving epoxy injection directly into the bundle
to repair leaks internally has been used. Maintenance techniques cur-
rently involve washing and physical inspection of the bundles on a once-
per-month basis. The cycling of warm water in out-of-service bundles to
maintain approximately a 2 C (4 F) temperature differential with ambient
air is also under consideration. Freezing is not a serious problem,
however, due to the winter peak experienced at this plant.
VOLKSWAGEN PLANT (19)
This unit is located in the West German city of Wolfsburg whose .
primary industry is the Volkswagen plant. The GEA unit condenses steam
from four turbine generators of 48 MW capacity each. Figure 17 is a
photo of the unit. Two condensers were installed in 1961, another in
1966 and the last in 1972. There are also wet cooling towers which
serve the old power plant. Prinicipal reasons.for visiting this plant
were to compare the different GEA designs for the three vintages of
condenser, and to observe the relative condition of galvanized fintubes
differing in age by more than 10 years.
Blocks A and B (1961) each have four condenser groups, three of
which are parallel flow and one of which is counterflow (dephlegmating).
30
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FIGURE I5~ NATURAL-DRAFT COOLING TOWERS ATC.E.G.B. GENERATING STATION
RUGELEY, ENGLAND
(DRY TOWER IS SHORTER , WIDER-MOUTH UNIT)
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FIGURE 16 — EXAMPLE OF THE OLDEST EPOXY-COATED FINTUBE BUNDLES AT
C.E.G.B. PLANT - RUGELEY, ENGLAND
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J
•
FIGURE 17 —GEA CONDENSER AT VOLKSWAGEN PLANT
WOLFSBURG, WEST GERMANY
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The condenser groups are isolable through shutoff devices in the steam
and evacuation lines. An aftercondenser upstream of air evacuation
equipment is shown in Figure 18. Block C has four groups, each having a
counterflow section in the center and two parallel flow sections ar-
ranged at the ends. These hookups permit different operating modes.
For ambient temperatures below 0 C, Blocks A and B are started up
with only the dephlegmators. With increasing exhaust flows, the three
dephlegmator fans are started sequentially at reduced rpm and are finally
operated at high speed. The parallel flow groups remain shut off. As
the limit of dephlegmator capacity is approached, a parallel flow group
is brought on line in order to maintain vacuum. The cooling surface is
thereby increased, initially more than the steam flow would require. In
order to prevent condensate subcooling and possible icing of the tubes,
the added parallel flow group should immediately be heavily loaded with
steam. This is done by shutting down the dephlegmator fans as soon as
steam is admitted to the parallel flow group and switching the parallel
flow unit fans to high speed. The dephlegmator loading, in this case,
is only the excess over the capacity of the parallel flow units just
placed on the line. A further increase in steam flow is accommodated by
loading up the dephlegmators, i.e., re-energizing the fans, and finally,
the second and third parallel flow groups are likewise put on line.
Block C is started up a group at a time. A control sequence first
energizes the fans of the dephlegmator elements and then those of the
parallel flow sections. The other groups are similarly put into opera-
tion, depending upon demand. A diagram shows the operator the tempera-
ture and load points for fan speed cutback and eventual shutdown.
Condenser response to variations in load and air temperature is
achieved by air flow adjustment. It should be noted that there is an
economic limit beyond which the cost of added fan power consumption for
increased air flow exceeds the fuel cost savings resulting from vacuum
improvement.
Control of air flow for units A through C is accomplished by means
of two-speed motors. However, these coarse steps require frequent speed
changes at light loads, and a different means was, therefore, chosen for
Block D. It has three parallel flow groups each of which includes a
small counterflow unit, and a startup group having two of three sections
that may be connected in the parallel flow or dephlegmator mode. This
startup group is equipped with variable pitch fans, permitting better
accommodation of load conditions at low temperatures.
As regards the aging of galvanized fintubes, the oldest units have
turned a dark dull color, in contrast to the light gray surface of the
newest unit. The only noticeable corrosion is where mechanical acci-
dents have removed the galvanizing, allowing, oxidation of the underlying
steel fintube. This corrosion has not, however, significantly altered
the heat transfer capability of the units.
34
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PIGURE 18 - AFTERCONDENSER ON OLDEST GEA CONDENSER(DEPHLEGMATOR)
AT VOLKSWAGEN PLANT - WOLFSBURG, WEST GERMANY
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PREUSSAG A. G. IBBENBUREN STATION (20)
Located in a rural coal-mining village in north-central West
Germany, Ibbenburen Station is the site of a 150 MW indirect, dry-cooled
generating unit. A description of the Heller system utilized with a
natural-draft tower has been prepared previously. Figure 19 is a photo
of this unit. Adjustable louvers on the outside of the air-cooled coils
are used for air flow control. The dry cooling equipment for this plant
was furnished by GEA. An older plant (vintage 1954), of 100 MW capa-
bility, is immediately adjacent and is cooled by two natural-draft wet
towers.
The principal reason for visiting this generating station was to
investigate minor fintube corrosion thought to have resulted from the
proximity of the coal mining/storage operation and the wet towers, sub-
sequent to a late 1969 visit. The fintube bundles have not been replaced
since their installation in 1967, and have been cleaned only twice by
air-blowing. The aluminum Forgo-type coils have experienced some cor-
rosion on the air inlet side.
Some fintube bundles were removed from service (see Figure 20) to
be analyzed for corrosive agents. Both chloride and sulfate ions have
been identified. These could have contributed to the localized, rather
than area-wide, attack which has occurred.
SCHMEHAUSEN CABLE-NET TOWER (21)
The construction site of a new type of natural-draft tower to serve
a 300 MW prototype high-temperature nuclear power plant using a pebble-
bed reactor is approximately 230 km (140 miles) north of Frankfurt, West
Germany. Figure 21 is a photo of the cable-net tower as it appeared in
July, 1975. The structural net, formed from aluminum-coated twin steel
cables, will be covered on the inside with corrugated aluminum sheets.
The German engineers feel that much larger natural-draft towers are
possible with this type of construction than currently deemed feasible
for conventional thin-shelled, reinforced concrete cooling towers.
Designers and contractors, with financial help from the government, have
decided to make the tower large enough to provide cooling for a 500 MW
plant.
The tower will have a slip-formed central core mast 180 m (590
feet) high, from which a circular, prestressed hyperboloid cable net is
suspended and anchored to a 140 m (460 feet) diameter concrete founda-
tion ring. The cable net will rise to a height of 150 m (480 feet)
where it is suspended from a 90 m (300 feet) compression ring. The ring
which forms the upper edge of the tower proper is, in turn, suspended
from the central mast top by 36 radial cables.
The heart of the cooling system are the heat exchangers inside the
tower. These will be laid out as three rings inclined at a 17 degree
36
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FIGURE 19 — NATURAL-DRAFT DRY TOWER AT PRE USSAG
A.G. GENERATING STATION
IBBENBUREN, WEST GERMANY
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FIGURE 20— FINTUBE BUNDLES SUBJECTED TO CORROSION
ANALYSIS AT PREUSSAG A.G. GENERATING STATION
IBBENBUREN, WEST GERMANY
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FIGURE 21 — CABLE NET (TO BE FINISHED WITH ALUMINUM SHEETING)
NATURAL-DRAFT DRY TOWER UNDER CONSTRUCTION
SCHMEHAUSEN, WEST GERMANY
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angle to the tower's center. Their inclination results from the re-
quirement that equal air flow velocities should prevail in all areas of
the heat exchange surface. The individual cooling elements, about 15 m
(50 feet) long, consist of two tube walls which are inclined at an angle
of 60 degrees to each other in an A-frame manner. Most of the fintube
bundles will be supplied by GEA and will consist of steel tubes with
oval cross-section and slipped-on steel fins. For the purpose of ex-
perimentation, the remainder of the bundles will be supplied by Balcke-
Durr, another Bochum firm, and will consist of steel tubes with oval
cross-section and wound-on steel ribs. All bundles will be liquid
galvanized.
UNION TERMICA S. A. UTRILLAS STATION (22)
This GEA unit is located in a mountainous area of Spain, approxi-
mately 240 km (150 miles) east of Madrid. The unit condenses steam from
a 160 MW power plant near an underground lignite mine. Figure 22 is a
photo of this condenser, which was commissioned in 1970, and is, to
date, the world's largest direct, air-cooled system. Operating per-
sonnel indicated that the unit has performed its design function and
achieved expected performance over an extreme range of ambient tempera-
tures. The unit is back-washed once a year with air and water and was
observed to be in excellent condition. Plans are currently underway for
development of an additional steam unit at the plant of approximately
300 MW capacity, with another dry tower.
AMMONIA PLANT - NANGIS, FRANCE (23)
The air-cooled heat exchangers were manufactured by Creusot-Loire,
under license from Hudson Products Corporation and are of Hudson design.
Air-cooled heat exchangers serve as steam condensers for turbines which
drive compressors and a 7 MW electrical generator, operating under
vacuum conditions. Two-speed fan motors and auto-variable fans provide
freeze protection. Operators reported no freezing of the coils. Tubes
are of steel with extruded aluminum finss. No fin corrosion has been
experienced. In addition to the vacuum steam condensers, there are a
number of Hudson air-cooled heat exchangers for ammonia condensing.
PARIS METRO SUBWAY AIR CONDITIONING SYSTEM (24)
This three-unit Hudson air-cooled heat exchanger, manufactured by
Creusot-Loire, is located on a rooftop next to the Paris Opera House.
Because of this location a low noise level of 65 dB(A) at 1 m (3 feet)
with all fans at full speed was specified. The noise level is extremely
low and normal conversation can be heard directly below the fans. No
corrosion was evident on the extruded aluminum fins.
40
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•*
FIGURE 22
GEA CONDENSER AT UNION TERMICA, S.A.GENERATING STATION
UTRILLAS, SPAIN
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SECTION VI
PREVENTION OF FINTUBE CORROSION
Two factors are of prime importance in determination of the useful
life of fintube bundles in dry cooling towers. These are the construc-
tion and manufacture of the fintube itself and the atmospheric environment
in which it is used. Figure 23 depicts several basic fintube designs.
Illustration (a) is the GEA fintube, consisting of steel plate fins over
oval steel tubes with the entire assembly hot-dip galvanized after
fabrication. Illustration (b) is the L-fin quite commonly used in LATEC
units. This is an L-shaped aluminum fin wrapped on a steel tube under
tension. Illustration (c) is the embedded (G-type) fin, made by wrapping
aluminum fins into a spiral groove in a steel tube, followed by rolling
the tube material against the fin base. These are also used in LATEC
units. Illustration (d) is the extruded fin of aluminum over a steel
tube. Extruded fin tubes, combined with tube end coatings, provide a
complete protective sheath over the steel tube and effectively prevent
corrosion of the steel tube and galvanic corrosion of the aluminum fin.
Illustration (e) is the overlapped version of the L-fin. Illustration
(f) is the "Forgo" fintube consisting of aluminum slotted plate fins
over aluminum tubes. Any of these fintube designs can probably give
satisfactory service in a seacoast environment, without severe industrial
contamination.
Fintubes which can allow the moisture in the air to come into
contact with steel tubes may, however, be subject to corrosion. The
embedded type of fintubes falls into this category, while careful
manufacture of the L-fin type can alleviate this problem.
GEA's experience has been that the service life of their fintube
bundles has been adequate for all air-cooled condenser applications —
based on coating with an appropriate zinc compound. The thickness of
the zinc coating depends on the anticipated atmospheric environment.
GEA feels that a marine atmosphere is less corrosive than either an
urban or industrial area. The main corrosive agents that reduce the
service life of galvanizing are thought to be sulfur compounds, although
sea spray in direct contact with the fintube surface is also known to
cause corrosion.
Lummus normally uses the aluminum L-fin tube. Aluminum is considered
to be most susceptible to marine and industrial environments although
Alclad products offer supplemental protection in the form of a sacrificial
cladding. The corrosion experienced by aluminum L-fins at the Albatross
refinery (see Section V) is thought to result from the exceptionally
severe environment at the site. Much the same experience has been noted
with the Forgo type fintubes at Rugeley and to a lesser extent at Ibben-
buren. The replacement epoxy-coated fintubes at Rugeley have seen
longer service, with a slight increase in heat transfer capability.
42
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Hudson recommends extruded aluminum finned tubes for most steam
condensers, but they also offer embedded or plate fin tubing in either
aluminum or steel. Their experience is that extruded aluminum fin tubing
is adequate except where chemical pollutants in an industrial atmosphere,
in combination with a low tube wall temperature permitting liquid water
on the fin surface, results in a specific chemical degradation of the
aluminum. Hudson considers extruded aluminum fin tubing adequate for
power plants, located in relatively benign rural settings, but also for
locations, such as Rugeley or Ibbenburren, where corrosion has taken
place due to the presence of solid chemical pollutants and moisture at
the crevice between the fin and tube.
43
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to) GEA ELLIPTICAL FINTUBE
i\\vv\V\
(b) L-SHAPE
FOOTED FIN
(d) EXTRUDED
FIN
(c) EMBEDDED
FIN
(•) OVERLAPPED
FOOTED FIN
^^^^^^Pr
(f ) HELLER- FORGO
SLOTTED PLATE FINS
FIGURE 23- TYPES OF FINTUBE CONSTRUCTION
44
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SECTION VII
PREVENTION OF COIL FREEZING
Many of the direct air-cooled condensation systems which have been
investigated have recorded incidents of freezing, e.g., Wyodak, Condea
refinery, Linde plant, Wolfsburg, Columbia Gas S. N. G. plant. Most of
these Incidents have been attributed by the manufacturers to improper
operating procedures. All freezing episodes took place at low loads or
during startup. None of the units investigated have encountered any
difficulty with freezing when operating at design load. The special
freeze protection features of the units offered by GEA, Lummus and
Hudson Products Corporation are explained below.
GEA SYSTEM (With Reference to Figure 1)
In a multi-row tube bundle the cooling air is heated gradually as
it passes over successive rows of tubes. Since the condensation temper-
ature is approximately the same in all tubes, the temperature difference
for heat transfer decreases in the direction of air flow. If the heat
transfer surface area is the same for each row of tubes, the condensing
capacity of subsequent rows likewise decreases. Since all tubes are
subject to the same steam pressure drop, the steam flow is virtually the
same for all tubes. If the bundle is designed so that all of the steam
passing through the last row of tubes is condensed, it follows that the
steam passing through the previous rows of tubes which are in contact
with colder air will be completely condensed before reaching the end of
the tubes. Once condensation is complete in a parallel flow condenser
tube, the condensate will be subcooled as it passes through the re-
maining length of tube or "dead zone."
The subcooled condensate will also pick up oxygen from the non-
condensible gas mixture which collects in the "dead zone" of the tubes.
This can result in corrosion of the tubes, headers and other Internal
parts of the condenser. If the ambient air temperature is below 0 C
(32 F), the condensate may freeze and rupture the condenser tubes.
A counterflow condenser in which steam and condensate flow in
opposite directions avoids this problem since the condensate is always
in close contact with steam. However, with the steam flow opposing the
condensate, the condensate film will be thicker than for parallel flow.
The thicker condensate film will reduce heat transfer and may increase
steam pressure drop to such an extent that the condensate may tempor-
arily build up in the tubes with subsequent rapid discharge which can
cause freezing.
GEA has found that the most effective solution to the "dead zone"
problem is a combination of parallel and counterflow condenser elements.
The steam entering the condenser first passes through parallel-flow
45
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bundles. These are so designed that, under all operating conditions,
excess steam leaves all tubes with more steam coming from the last tube
rows than from the first one. This excess steam is transferred by means
of a large diameter carry-over pipe to the subsequent counterflow.bundles
where it is condensed. The noncondensible gases are extracted from the
upper end of the counterflow tubes after having been cooled several
degrees below the steam saturation temperature.
In the GEA design, large internal cross-section elliptical tubes
are mounted in an inclined position to ensure good condensate drainage
from all units. An additional feature of the GEA condenser is the use
of fintubes with variable fin pitch which decreases from tube row to
tube row in the direction of air flow. This means that the heat trans-
fer surface increases from tube row to tube row to compensate for the
decrease of the effective temperature difference. A secondary effect of
variable fin pitch is that, due to the large fin spacing of the first
tube row, cleaning of the fin surface by means of high-pressure water
jets is facilitated.
In addition, GEA units are equipped with two-speed fan motor drives
which permit a control scheme whereby the heat rejection capability of
the air-cooled condenser can be closely matched to load over the entire
range of operating conditions. Thus, careful attention to explicit
operating Instructions should prevent coil freezing.
LUMMUS SYSTEM (With Reference to Figure 2)
LATEC freeze protection is provided by a combination of basic
design configuration, cooling air flow control and isolation of effec-
tive surface.
The conventional single-pass air-cooled condenser design is prone
to freezing problems in cold weather due to subcooling in the lower end
of the tubes, recirculation of noncondensible gases from the higher
pressure areas of the condenser and subsequent tube blockage. The Lummus
HTD double U-tube design features separate condensate headers for each
flow path and a loop seal arrangement which prevents the aforementioned
recirculation and blockage. This design ensures uniform flow and heat
flux distribution over a wide range of ambient temperatures and steam
flows. In addition, the U-tube design in conjunction with co-current
cooling air flow ensures that the condensate leg is in contact with warm
air. The design is such that cooling air reaching the condensate legs is
warmer than 0 C (32 F) under all specified operating conditions.
The type and extent of airflow control and/or surface isolation
used depends on a number of factors, namely:
Minimum ambient temperature
. Minimum steam flow
Wind velocity and direction
Allowable backpressure variation
Size of unit
46
-------
In areas subject to moderate freezing (down to -18 C), freeze protection
and backpressure control can be maintained with either two-speed motors
or automatic variable pitch fans. Whether all or only half the fans are
so equipped depends on the size of the unit, or the relative size of a
step change.
At temperatures below -18 C (OF), consideration is given to iso-
lating steam valves which remove sections from service or modulating
louvers to regulate cooling air flow. For maximum protection under
severe wind conditions, preference would be given to the use of louvers.
In this case, the (inverted) M-type module which offers a "built in"
wind screen would be offered.
From steam distribution considerations, it is preferred to have all
condenser sections operating at equal cooling capacity. For units
equipped with two-speed motors and louvers, all louvers are operated
from a common signal and assume the same position for all sections in
operation. With decreasing load, louvers are adjusted to reduce air
flow as long as louver position in the air stream is satisfactory from a
control standpoint. Below this, motors are switched from full to half
speed and the louvers are reopened as required to compensate for the
reduced fan draft. Further load or ambient temperature reductions can
be accommodated by turning motors off, the number depending on the
relative size of the step change.
Isolating steam valves can also be used with or without louvers,
but generally with either two-speed motors or auto-variable fans. The
specific control system selected is matched to plant requirements. With
the exception of simple auto-variable fan pitch control, all systems can
be manual, semiautomatic or fully automatic. Here again, the degree of
automation is tailored to the specific plant requirements of operator
attention and cost of instrumentation.
HUDSON SYSTEM
The major problem in design of vacuum steam condensers is accommo-
dating the fact that all steam contains at least some air. It has become
common practice to utilize either a vent condenser or a dephlegmator
after and in series with the main condenser to minimize air binding and
the potential of condensate freezing. The systems are designed such that
excess steam actually "blows" through the main condensers, displacing the
final condensation and air removal to the aftercondenser. Ideally, suf-
ficient steam should pass to just provide positive flow in the bottom
row. Since the aftercondensers are less efficient as steam condensers
and may require more expensive anti-freeze devices, their cost per Btu
of heat removal is high. Thus, it is desirable to minimize that portion
of the condensing surface which is aftercondenser.
For the more demanding condenser application with respect to freezing,
Hudson utilizes an internal means of varying steam flow in proportion to
the temperature driving force in each row, thus minimizing the amount of
47
-------
steam that must be blown through the main to prevent freezing, and
minimizing the size of the aftercondenser. Manufacturers who do not
provide such proportioning must either pay the price for a larger
aftercondenser and its reduced capacity in the summer, or must provide
a means of manifold valving to reproportion the surface between the
mains and the aftercondensers on a seasonal basis.
To deal with these considerations, Hudson combines a number of
in-tube and air side features chosen to provide a maximum of condensing
capacity in the summer with protective mechanism against freezing in
the winter, particularly at low steam loads and at startup and shutdown.
Hudson generally recommends automatic and modulating air side systems,
minimizing system shock and with less demands on operating personnel to
prevent freezeups. Modulated air control is unnecessary in equatorial
locations.
-------
SECTION VIII
NOISE ATTENUATION
The relationship of dry tower design parameters to sound pressure
levels is complex. Certain basic relationships do exist, however. For
example, doubling the number of fans of a given size will cause an in-
crease of 3 dB in the sound pressure level.
Halving fan speed will cause a reduction of 14 dB in sound pressure
level. Obviously, halving the rpm will cause a 50 percent decrease in
air flow rate if no compensating fan changes are made, such as more blades
or wider blades. Therefore, doubling the number of fans and halving the
fan speed will provide the same air flow rate with a net decrease in
sound of 11 dB.
The use of large slow-speed fans will generally produce lower sound
pressure levels than will smaller, higher-speed fans of the same capacity.
Other attenuation techniques include direct coupling of fan and
motor drive thus eliminating reduction gear whine, enclosure of the en-
tire dry tower structure, and acoustical baffling of the air inlet
plenum.
Two plants visited in the course of this research project were
representative of current practice. These plants were the Chevron
Refinery at Feluy, Belgium and the municipal incinerator at Zurich,
Switzerland. Sound pressure level readings were taken at each of these
sites with a General Radio Model 1933 Precision Sound-Level Meter. Re-
cordings were made on a Uher 4200 Report Stereo Tape Recorder, using a
General Radio 1562A calibrator to provide analysis information. Tape
analysis was performed on a General Radio 1521-B Graphic Level Recorder.
Field data taken at the Zurich Municipal Incinerator at an approxi-
mate distance of 220 feet from the geographical center of the unit
indicated an average sound pressure level of 61 dB(A). At a distance of
400 feet from the geographical center of the unit, a sound pressure
level of 56 dB(A) is forecast. It was noted during field monitoring
that steam turbine noise was the major contributor to the noise levels
observed.
Field data taken at the Chevron Refinery at Feluy, Belgium at a
distance of 50 feet from the unit's geographical center indicated an
average sound pressure level of 70 dB(A). At a distance of 400 feet
from the geographical center of the unit, a sound pressure level of 52
dB(A) is forecast. It was noted during field monitoring that steam
throttling was a major source of the observed noise levels.
49
-------
SECTION IX
APPLICATION OF A DIRECT. AIR-COOLED CONDENSATION SYSTEM
IN A COASTAL ENVIRONMENT
The Braintree, Massachusetts Electric Light Department (BELD) has
contracted to build an 85 MW combined cycle (gas turbine-steam turbine)
electric generating unit to be known as Norton P. Potter Station, Unit
No. 2. The exhaust heat from the 65 MW gas turbine will be utilized in
an unfired heat recovery boiler to produce steam for a 20 MW steam
turbine. Because of the utilization of gas turbine waste heat, the
generating unit will have a high thermal efficiency. The gross heat
rate, i.e. the amount of energy consumed to produce a kilowatt-hour
(kWh) of electricity, for the unit is expected to be 8,970 Btu/kWh (38
percent thermal efficiency), which is considerably better than most
generating alternatives.
During the course of the preliminary design and environmental in-
vestigations for Potter No. 2, it became evident that it would be costly
and time-consuming to attempt to secure permits for an open-cycle cool-
ing system. The use of water from the Weymouth Fore River Estuary would
require permits from the various federal, state and local agencies con-
cerned with environmental quality. A study of alternative methods for
cooling the plant showed that an air-cooled vacuum steam condenser would
result in an estimated power cost 2 percent higher than the cost of
power using an open-cycle system. In addition, due to the relatively
high cost of clean water suitable for use in evaporative cooling towers
($0.70 per 1000 gal), the power cost using the air-cooled condenser was
estimated to be no higher than using evaporative towers.
BRAINTREE AIR ENVIRONMENT
Prevention of external corrosion of the fintube bundles of a dry
tower, and prevention of coil freezing were very real concerns to BELD.
Situated on the Weymouth Fore River Estuary, there are definitely solu-
ble chloride salts in the air at the Braintree site. Other contaminant
levels, as noted in the Draft Environmental Analysis,^ (40 g/m^ of
sulfur dioxide — 24-hour average, 60 g/m^ of particulate — 24-hour
average, and 80 g/m^ of nitrogen dioxide — 24-hour average) are repre-
sentative of light industrial areas. Subsequent studies have indicated
that most of the suspended particulate matter is less than 1 micron in
diameter, with negligible amounts of trace metals. The Decennial Census
of U. S. Climate^ indicates a temperature range for Boston of 36 C (97 F)
to -22 C (-8 F), with sub-freezing temperatures on the average of 958 hours
per year.
NOISE REQUIREMENTS
Currently, the Commonwealth of Massachusetts regulations require
that new sources do not increase the broad band noise level in excess
50
-------
of 10 dB(A) above the ambient level. The Commonwealth of Massachusetts
also limits production of "puretone conditions" which exceed ambient.
A "puretone" is defined as an A-weighted sound level, at any given
octave band center frequency that exceeds the levels of adjacent center
frequencies by three or more decibels. As defined by the Commonwealth
of Massachusetts, the "ambient level" is that "A-weighted noise that
exists 90 percent of the time measured during the period in question."
In order to determine the ambi.ent levels in the Braintree area, noise
analyses were made during 1972 using acoustical instrumentation of
A.N.S.I. Type 2 standard.^ Noise samples were obtained in the daytime
and in late evening between 10 p.m. and midnight. For residential areas
close to the plant the residual noise levels are around 45 dB(A). This
value is within the typical range for urban residential areas.
The noise specification for the dry cooling tower limits sound
pressure levels to 51 dB(A) at 400 feet. The manufacturer has guaranteed
that he will meet these requirements. Field data from the European low-
noise installations indicated somewhat higher levels. For example, the
Chevron Refinery at Feluy, Belgium would have a forecast sound pressure
level of 52 dB(A) at 400 feet. However, approximately three times more
cooling capacity will be required at Braintree than at Feluy. Tripling
the plant size might increase noise levels by as much as 5 dB(A) re-
sulting in a noise level approximately equal to the predicted level for
the Zurich incinerator. However, the interference of other sound gener-
ating components exclusive of the dry cooling towers at both Feluy and
Zurich have raised the recorded levels somewhat.
SPECIFICATION OF THE BRAINTREE CONDENSER
The condensing duty of Potter No. 2 is approximately 45 Gcal per
hour (180 MM Btu per hour), which is well within the range of operating
installations as indicated in Table 1. Table 2 lists design conditions
for fifteen direct, air-cooled condensers which were visited in the
course of this research project. The two parameters of greatest concern
to equipment manufacturers are the turbine backpressure and the initial
temperature difference (I.T.D) between condensing steam and ambient air.
Turbine heat rate decreases with decreasing backpressure and the amount
of fintube surface required for a specified duty varies inversely with
I.T.D. The GEA dry tower for Braintree has been selected on the basis
of 0.12 atm (3.5 inch Hg) backpressure, or a design I.T.D. of 34 C
(62 F). The benefits of unit operating economy offset the initial
capital cost penalty of this size tower. The other design data for
Potter No. 2 are: steam flow - 86,000 kg per hour (190,000 pounds per
hour), exhaust steam temperature - 49 C (121 F) and ambient air tempera-
ture - 15 C (59 F).
Table 3 lists the site conditions for the 15 sites referred to
above where air-cooled condensers have been successfully applied.
Braintree conditions are within the range of conditions shown.
51
-------
Table 2. DESIGN DATA FOR DIRECT, AIR-COOLED CONDENSATION SYSTEMS
No.* Steam
1
3
5
6
7
8
9
11
14
15
16
17
19
22
23
Kg /Mr
76,000
20,000
34, 000
51, 000
137,000
6,000
70,000
31, 000
45,000
30, 000
440, 000
520, 000
92,000
Flow
Lb/Hr
168, 000
44, 000
76, 000
NA
NA
112, 000
302,000**
12,000
154, 000
68, 000
100, 000
65, 000
970,000**
1, 150,000
188,000
Steam
Pressure
Atm.
. 15
. 17
.28
. 08
. 19
. 25
. 12
. 10
. 15
. 11
. 17
.09
. 10
. 10
In. Hg
4. 5
5.0
8.4
2.4
NA
5.7
7.5
3.6
3. 0
4.6
3.2
5. 1
2.7
2.9
2.9
Steam
Temperature
°C
54
57
68
42
59
66
53
46
55
47
57
44
46
46
°F
130
134
154
108
NA
139
. 150
127
115
131 .
117
135
111
114
114
Aii-
Tempcrature ITD
°C °F °C °F
24 75 30 55
17 62 40 72
27 80 41 74
15 59 27 49
NA NA
NA NA
32 90 34 60
32 90 21 37
20 68 26 47
NA NA
NA NA
NA NA
15 59 29 52
15 59 31 55
25 77' 20;; 37
* Numbers refer to installations with like designation in Table 1
** Total of several condensers
52
-------
GEA has selected a design for the Braintree application embodying
twin A-frame units comprised of 60 bundles of galvanized elliptical
tubes with plate-type fins. Ten two-speed fans (110 rpm/55 rpm) with
4.9 meter (16 feet) blades will provide air movement. Similar configur-
ations are used at Zurich (7) and Feluy (17) as shown in Table 4. The
GEA bid guarantees noise levels from this arrangement will not exceed 52
dB(A) at 400 feet. The bid also lists performance data for each of
octave bands 1-8. The levels specified in each band satisfy the Common-r
wealth of Massachusetts criteria for "puretone" generation. The 52
dB(A) sound pressure level, when combined with a similar sound pressure
level generated by the combined-cycle unit, should produce a 55 dB(A)
sound pressure level at 400 feet for both units. Since ambient residual
sound pressure levels are approximately 45 dB(A), the addition of this
total plant would satisfy the Commonwealth of Massachusetts' 10 dB(A)
maximum increase criteria at the property line (approximately 700 feet
from the units).
EVALUATION OF AIR-COOLED COMBINED CYCLE PLANT PERFORMANCE
Economic analyses were made to determine total bus-bar energy
production costs for the Braintree dry-cooled combined cycle plant for
various combinations of values of economic and operating parameters. All
costs associated with the plant and/or affected by its operation were
included in the analyses. These costs include the evaluated capital
costs of the combined-cycle unit and the air-cooled condenser, including
the supplemental evaporative cooling system for auxiliary cooling;
annual makeup water costs for the supplemental system; and annual plant
fuel costs.
Total bus-bar costs were based on the gross annual generation of
the combined cycle unit minus the annual fan energy requirements for the
air-cooled condenser and the supplemental evaporative cooling system.
The plant was assumed to operate 7500 hours per year with specified
percentages of each operating hour to be at nominal 100-, 80- and 60-
percent-load conditions. Full-power operation of the supplemental
evaporative cooling system was assumed throughout the operating period.
Fuel rate, gas turbine output and waste heat-generated steam flow
at a given nominal load condition are functions of ambient temperature.
For given throttle steam flow conditions, steam turbine-generator output
varies with exhaust pressure which, for a given air-cooled condenser
design and mode of operation, is also a function of ambient temperature.
Manufacturers' performance data for the gas turbine, waste heat boiler,
steam turbine-generator and air-cooled condenser were used in the
analyses.
Although the actual control scheme for the GEA air-cooled condenser
provides for 13 different combinations of fan operating conditions, only
three combinations were considered in the present analyses; viz.: all
fans full-speed, all fans half-speed, or all fans shut off. For a given
53
-------
Table 3. SITE CONDITIONS FOR DIRECT, AIR-COOLED CONDENSATION SYSTEMS
No. # Elevation
1
3
5
6
7
8
9
11
14
15
16
17
19
22
23
rri
1200
0
100
0
400
100
200
0
200
100
100
100
100
700
100
ft
3900
0
300
0
1300
300
800
0
700
400
200
300
200
2200
300
Minimum
Temperature
~oc °F
-35
-16
-18
-19
-18
-22
-23
. -4
-26
-7
-16
-18
-24
-10
-23
-31
3
0
-3
-1
-7
-9
24
-14
20
4
0
-11
14
-10
Maximum
Temper n tu r e
bc "SF
41
35
-
37
33
38
38
39
32
37
40
40
37
37
39
40
106
95
98
91
101
100
103
90
98
104
104
98
98
102
104
Average
Temperature
°£
7
10
10
8
10
10
11
21
9
16
11
10
9
13
11
°F
44
50
50
46
50
50
51
70
49
61
51
50
48
56
51
Environment
rural arid
seacoast
refinery
sear.oast
industrial
Beacoast
refinery
urban
light, industrial
rural
seacoast
industrial
industrial
urban
refinery
refinery
industrial
coal mine
industrial
* Numbers refer to installations with like designation in Table 1.
54
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Table 4. DESIGN SPECIFICATIONS FOR DIRECT, AIR-COOLED CONDENSATION SYSTEMS
No.*
1
3
5
6
7
8
9
11
14
15
16
1
17
19
22
23
Number Fan Fan Fintube
of Fans Diameter Configuration Construction
rn ft
6 6.4 21 2x3 galvanized el-
liptical tube
: plate -type fins
NA NA NA galvanized el-
liptical tube
plate -type fins
3 NA 1x3 galvanized el-
liptical tube
plate -type fins
3 NA 1x3 galvanized el-
liptical tube
plate -type fins
8 6. 1 20 2x4 galvanized el-
liptical tube
plate-type fins
10 NA 2x5 Al L-fins
NA NA . NA Al embedded
fins
A •
4.013 4x1 Al extruded
8 6. 1 20 2x4 Al spiral-wound
fins
12 4. 3 14 3x4 Al G-fins
24 NA 4x6 Al L-fins
4 5. 5 18 2x2 Al L-fins
48 6. 5 21 8x6 galvanized el-
liptical tube
plate-type fiiin,
40 3.0 10 8x5 galvanized el-
liptical tube
plate-type fins
68 3; 1 10 34x2 Al extruded
Number
Bundles
48
NA
18
18
44
20
NA .
4
24
36
NA
12
120/96/72
240
68
Bundle Con-
figuration
2 A-frame
NA
A-frame
A-frame
2 A-frame
A-frame
NA
nearly
horizontal
A-frame
nearly
horizontal
2 A-frame
A-frame
8 A-frames
8 A-frames
nearly
horizontal
* Numbers refer to installations with like designation in Table 1.
55
-------
nominal load condition, it was assumed that when the ambient temperature
decreased to where the minimum heat rate condition for the steam turbine
was reached, fan speed would be reduced to the next lower level provided,
however, that such reduction did not result in a backpressure greater
than 10 inch Hg.
Annual plant performance was evaluated on an hourly basis, taking
into account the annual durations for each five degree F interval over
the range of ambient temperatures normally experienced at Braintree.
The annual temperature durations, in percent of total hours, were as-
sumed to be applicable also to the 7500 hours per year during which the
plant would operate.
A computer program, a listing of which is included in the Appendix,
was developed to facilitate the performance and economic analyses. The
program provides for input of the following data:
1. Number of annual fixed-charge rates to be considered (maximum
of three) and annual fixed-charge rates;
2. Number of unit fuel costs to be considered (maximum of three)
and unit fuel costs;
3. Number of unit makeup water costs to be considered (maximum
of three) and unit makeup water costs;
4. Percentage of total annual hours of operation during which
plant is to operate at nominal 100-, 80- and 60-percent-load
conditions, respectively.
All other design, performance, operating and cost data are incorporated
in the computer program in DATA statements or in equation form.
VARIABLES AFFECTING BUS-BAR ENERGY PRODUCTION COSTS
Annual Fixed-Charge Rate
The annual fixed-charge rate is applied to the total capital cost
in order to determine the annual costs of the following items as defined
by the Bureau of Power of the Federal Power Commission:
1. Interest, or cost of money.
2. Depreciation, or amortization.
3. Interim replacements.
4. Insurance, or payments in lieu of insurance.
5. Taxes (federal, state and local), or payments in lieu of
taxes.
56
-------
Annual fixed-charge rates of 12, 15 and 18 percent were considered in
the present analyses.
Unit Fuel Costs
Of the costs considered in evaluating the performance of the dry-
cooled combined cycle plant, fuel costs represent the major component of
the total bus-bar costs determined.
Unit fuel costs of $1.75, $2.00 and $2.25 per million Btu were
considered in the analyses.
Makeup Water Costs
For the dry-cooled plant, cooling water makeup requirements are
minimal; amounting only to the evaporation, blowdown and drift losses
from the supplemental evaporative cooling system used to provide aux-
iliary cooling. Therefore, makeup water costs represent only a small
percentage of total annual costs and, hence, bus-bar energy production
costs are not appreciably affected by variations in unit makeup water
costs.
For the present analyses, makeup water requirements were assumed to
be 2.0 percent of the design circulating water flow for the supplemental
evaporative cooling system. Unit makeup water costs of $.70 per 1000
gallons were used.
Load Demand Profile
In general, bus-bar energy production costs for a plant will be a
minimum when the plant is base-loaded. Scheduled and unscheduled down-
time and daily and seasonal variations in load demand will result in an
annual plant load factor considerably less than 100 percent, however.
In the primary analysis, it was assumed that the plant would operate
50 percent of the total operating hours at a nominal 100-percent-load
condition, 25 percent of the time at 80-percent-load and 25 percent of
the time at 60-percent-load. For purposes of comparison, another analy-
sis was made assuming that the plant would operate 100 percent of the
total operating time at a nominal 100-percent-load condition.
Backpressure Control Range
Optimizing the performance of the dry-cooled plant for a given load
demand profile is essentially a matter of determining the steam turbine
operating backpressure range for which the net annual generation will be
a maximum. The increase in gross generation at lower backpressure must
be balanced against the potential decrease in auxiliary energy require-
ments attendant to a reduction in fan speed.
57
-------
The Braintree air-cooled condenser is designed to control steam
turbine backpressure between 2.3 and 3.0 inches Hg absolute by use of a
13-step fan control scheme. With only a 3-step control scheme con-
sidered in the present analyses, backpressure was maintained between 2.0
and 10.0 inches Hg absolute.
Operating and Maintenance Costs
Annual operating and maintenance costs for the plant were assumed
to be 1.0 percent of the total capital cost.
RESULT OF ANALYSES
Two sets of output from the Air-Cooled Combined Cycle Plant program
(ACCCPB) are presented in the Appendix. As discussed above, the program
was run for the Braintree plant with GEA air-cooled steam condenser for
three fixed-charge rates, three fuel costs and a single cost of makeup
water. The total bus-bar energy costs calculated for the specified
primary 7500-hour annual load profile ranged from 21.4 mills per kWh to
28.3 mills per kWh. In addition, the savings achievable by running the
plant at full-load for the entire 7500-hour schedule were determined to
be approximately 1.8 to 2.4 mills per kWh.
58
-------
REFERENCES
1. Armstrong, C. H. and Scheraerhorn, R. S., "Economics of Dry
Cooling Towers Applied to Combined-Cycle Plants," ASME Paper No.
73-WA/Pwr-5, November, 1973.
2. R. W. Beck and Associates, "Research on Dry-Type Cooling Towers for
Thermal Electric Generation," Parts I and II, for the Water Quality
Office of the Environmental Protection Agency, November, 1970.
3. "Decennial Census of U. S. Climate - Summary of Hourly Observa-
tions," Boston, U. S. Department of Commerce Weather Bureau, 1963.
A. R. W. Beck and Associates, "Draft Environmental Analysis -
Norton P. Potter Station Unit No. 2," for Braintree Electric Light
Department, July, 1973.
5. "American National Standard Specification for Sound Level Meters,"
ANSI SI.4, 1971.
6. "Community Noise," U. S. Environmental Protection Agency NTID
300.3, December, 1971.
59
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APPENDIX
AIR-COOLED COMBINED CYCLE PLANT
PERFORMANCE EVALUATION
60
-------
EVALUATION OF BRAINTREE COMBINED CYCLE PLANT
WITH GEA AIR-COOLED CONDENSER
ANNUAL PLANT LOAD FACTOR = 72.8 PERCENT
ANNUAL
FIXED-
CHARGE
RATE
PERCENT
12.0
12.0
12.0
15.0
15.0
15.0
18.0
18.0
18.0
UNIT
FUEL
COSTS
I/MMBTU
1.75
2.00
2.25
1.75
2.00
2.25
1.75
2.00
2.25
UNIT
MAKEUP
WATER
COSTS
$/1000 GAL
.70
.70
.70
.70
.70
.70
.70
.70
.70
GROSS
ANNUAL
GENER-
ATION
MWH
564650
564650
564650
564650
564650
564650
564650
564650
564650
ANNUAL
AUXILIARY
ENERGY
REQUIRED
MWH
2156
2156
2156
2156
2156
2156
2156 '
2156
2156
NET
ANNUAL
GENER-
ATION
MWH
562494
~ 562494
- 562494
562494
562494
562494
562494
562494
562494
ANNUAL
MAKEUP
WATER
REQUIRED
1000 GAL
14400
14400
14400
14400
14400
14400
14400
14400
14400
ANNUAL
CAPITAL
AND 0+M
COSTS
$
2665000
2665000
2665000
3280000
3280000
3280000
3895000
3895000
3895000
ANNUAL
FUEL
COSTS
$
9352189
10688216
12024243
9352189
10688216
12024243
9352189
10688216
12024243
ANNUAL
MAKEUP
WATER
COSTS
$
10080
10080
10080
10080
10080
10080
10080
10080
10080
\TOTAL
ANNUAL
COSTS
$
12027269
13363296
14699323
12642269
13978296
15314323
13257269
14593296
15929323
TOTAL
BUSBAR
ENERGY
COSTS
MILLS/KWH
21.382
23.757
26.132
22.475
24.851
27.226
23.569
25.944
28.319
-------
EVALUATION OF BRAINTREE COMBINED CYCLE PLANT
WITH GEA AIRr-COOLED CONDENSER
ANNUAL PLANT LOAD FACTOR = 85.6 PERCENT
ANNUAL
FIXED-
CHARGE
RATE
PERCENT
12.0
12.0
12.0
15.0
15.0
15.0
18.0
18.0
18.0
UNIT
FUEL
COSTS
$/MMBTU
1.75
2.00
2.25
1.75
2.00
2.25
1.75
2.00
2.25
UNIT
MAKEUP
WATER
COSTS
$/1000 GAL
.70
.70
.70
.70
.70
.70
.70
.70
.70
GROSS
ANNUAL
GENER-
ATION
MWH
680790
680790
680790
680790
680790
680790
680790
680790
680790
ANNUAL
AUXI LIARY
ENERGY
REQUIRED
MWH
2729
2729
2729
2729
2729
2729
2729
2729
2729
NET
ANNUAL
GENER-
ATION
MWH
678061
678061
678061
678061
678061
678061
678061
678061
678061
ANNUAL
MAKEUP
WATER
REQUIRED
1000 GAL
14400
14400
14400
14400
14400
14400
14400
14400
14400
ANNUAL
CAPITAL
AND 0+M
COSTS
$
2665000
2665000
2665000
3280000
3280000'
3280000
3895QOO
3895000
3895000
ANNUAL
FUEL
COSTS
•t
4>
10613924
12130199
13646474
10613924
12130199
13646474
10613924
12130199
13646474
ANNUAL
MAKEUP
WATER
COSTS
$
10080
10080
10080
10080
10080
10080
10080
10080
10080
TOTAL
ANNUAL
COSTS
$
13289004
14805279
16321554
13904004
15420279
16936554
14519004
16035279
17551554
TOTAL
BUSBAR
ENERGY
COSTS
MILLS/KWH
19.599
21.835
24.071
20.506
22.742
24.978
21.413
23.649
25.885
-------
00010 PROGRAM ACCCPR(INPUT»OUTPUT)
0002'.IC
00,'30 DIMENSION T<22) »TDUR(22> »PCTLOD(3) >OBP(22r3) »BP(27) »
00j4,:.+ FAN8HP(22>3) »ST60UT{27»2) t AFCR<3) >UFC(3) »UMWC(3) »
00d5:i+ PCTHRS(3) »STGO(2)
Or- 6»C
OOT70C AMBIENT TEMPERATURE (F) ARRAY AND ANNUAL DURATION (PERCENT) DATA
OOOROC FOR BOSTON
oongoc
nni ,i DATA T/97.»92.»87.>82.»77..72.»67.>62.»57.»52.»47.>42.>37.»
00110+ 32.»27.»22.»17.rl2.» 7. » 2.»-3.»-8./
00120 DATA TDUR/0.11.0.44,1.45»2.79»4.94»7.71»9.34r9.18>8.93>8.73f
00130+ 8.62>9.48>9.71>7.63>4.92>2.90»1.70r0.86»0.40»0.12f
00140+ 0.03»0.01/
00160C NOMINAL OPERATING LOAD (PERCENT) ARRAY
00170C
OOIfln DATA PCTLOD/100.»80.»60./
O.J190C
OOP'.nc STEAM TURRINE OPFRATING RACK PRESSURE (IN. HGA) AS A FUNCTION OF
c AMBIENT TEMPFRATURE AND NOMINAL LOAD CONDITION
00230 DATA OBP/fl.90»7.90 »7.00 »6.21 » 5.50» <*.fl5»4.30» 3.80»3. 35»2.9fi>
00250+
00260+ 6.67»5.fl5»l:5.12»U.19»3.9«fr3.U6>3.05>2.69»2.37»2.10»
00270+ 3.fl5»3.36>2.93»?.55»2.23»2.00»2.00>2.00»2.00»2.00>
002flO+ 2.00»?.0'j»
00290+ 5.0U*U.35»3.flO»3.30»2.87»2.50»2.17>3.5«*»3.05»2.65»
0030 i+ 2.30»2.02f?.00,2.00»?.00»2.00>9.67»8.16>6.89»5.82»
00310+ «4..8fl>«*.08/
00320C
003.^0C RACK PRESSURE (IN. HGA) ARRAY
00350 DATA RP/2. 0»2.5»3. 0» 3.5r <*. Of U.5r 5. 0» 5.^» 6.0»6.5> 7. Or 7.5»8. 0>
00360+ R.5»9.0»9.5>10.0»10.5>11.0>11.5»12.0»12.5.13.0f 13. 5»
00370+ lf.0>1^.5>15.0/
00380C
00390C FAN RRAKE HORSEPOWER (HP) RESUIREMENT AS A FUNCTION OF AMBIENT
OOUOOC TEMPERATURE AND NOMINAL LOAD CONDITION
OOU10C
00«»20 DATA FANRHP/^SO.^SO.fUSO.rlSO.f^O.iUSO. »450. » ^50. >450. » .
OOU30+ *f50.»U50.»450.»**50.. »H50. » 75. t 75. » 75. r 75. »
OOU40+ 75. f 75. » 75. » 75.. »
0 OU50+ 1+50 . » 450 . > 450 . > 450 . > 450 . r 450 . » 450 . r 450, » 450 . >
00460+ 450. » 75. » 75. » 75. t 75. t 75. > 75. » 75. f 75. t
00470+ 75. » 75. > 75. » 75. »
00480+ 450.»450.»450.»450.»450.»450.r450. » 75. » 75. r
00490+ 75. i 75. ». 75. » 75. • 75. » 75. t 75. » 0.» 0.»
005):>+ 0.» 0.» 0.» O./
OD510C
005POC STEAM TURRINE-GENERATOR OUTPUT (KW) AT 190000 LB/HR AND 170000
OOS30C LB/HR THROTTLE STEAM FLOW WITH ENTHALPY OF 1420 BTU/L8 AS A
00540C FUNCTION OF BACK PRESSURE
OOSSOC
00560 DATA STGOUT/P11 1 1 . »21052. » 20949. »20«00. »20622. •20430. »20230.*
00570+ 20024. » 19816. » 19607. » 19402. vl 9202. /1 9007.. Iflrti9^
00580+ 1(»«39.» 18467.. 18304. »iai49./lS008^vl7»A2.* 17728. »
00590+ 17600. , 17476. • 17355. » 17236. » 17118. » 17000. »
63
-------
00600+
00610+
006?0+
00630+
006«»OC
00650C
0116600
OH670C
on7onc
00710C
OI1720C
00 7.10 C
00740C
00750
00760
00770
007HOC
oo79oc
00ft .;>C
00«10
00fl?0+
ormso
oonuo
ooflsoc
00ft60
OOB70+
OOflflO
OOH90C
00900
00910+
00920
00930
00940C
00950
00960+
00970
00980+
00900
010, )OC
01010C
01020C
01030
01040
01050
01060
01070
OlOftOC
01090C
01100C
OHIO
01120C
01130C
01140C
01150
01160
01170
OllflOC
01190
.tin73U.t18607.»1RU3U.»in?30.i1R015.»17795.t
17573. »1735fl. »17157. > 169f>9. »1A7QJ . . 16623. • 104^,5. ,
16316.»16176.»16044.»15P20.»15803..156QO.»15 ,80.»
15472.r15367.»15264.,15t6?.»15061..14961./
TOTAL CAPITAL COST OF BRAINTRE COMBINED-CYCLE PLANT WITH
GEA AIR-COOLED CONDENSER AND TOTAL ANNUAL HOURS OF OPERATION
DATA CAPCST/20500000./
DATA AOPHRS/7500./
CIRCULATING WATER FLOW RATF. (GPM)» EVAPORATION* BLOWOOw/N AMD
DRIFT LOSSFS (PFRCFNT)I AND POWER REQUIREMENTS (HP) FOR
SUPPLEMENTAL EVAPORATIVE SYSTEM FOR AUXILIARY COALING
DATA GPM/1600./
DATA ERDL/2.0/
DATA SEHP/30./
INPUT DATA
PRINT»*ENTER NUMBER OF ANNUAL FIXED-CHARGE RATES TO BE *f
•CONSIDERED AND VALUES*
PRINT»*(PERCENT)*»
READ»NFCR.(AFCR(I)>I=1»NFCR)
PRINT»*ENTER NUMBER OF UNIT FUEL COSTS TO BE CONSIDERED AND*»
* VALUES (S/MMBTU)*
READ»NUFC»(UFC(I).I=1»NUFC)
PRTNT»*ENTFR MUMBER OF UNIT MAKEUP WATER COSTS TO BE *»
•CONSIDERED AND VALUES*
PRINT»*(S/1000 GAL)*>
READ.NMWC»(UMWC(I)»I=1»NMWC)
PRINTr*ENTER PERCENTAGE OF TOTAL ANNUAL HOURS OF OPERATION *.
*WHICH ARE TO BE AT *
PRINT>*100-> flO- AND 60-PCT NOMINAL LOAD CONDITCONS* *»
RESPECTIVELY*
READ.PCTHRS
ANNUAL PLANT LOAD FACTOR (PERCENT)
SUMPLHsO.
DO 96 1=1»3
SUMPLH=SUMPLH+(PCTLOD(I)*PCTHRS(I))
96 CONTINUE
APLFACs(SUMPLH/100.)*(AOPHRS/R760.)
ANNUAL MAKEUP WATER REQUIREMENTS (1000 GAL)
ANNMWR=GPM*60.*AOPHRS*(EBDL/100.)/1000.
ANNUAL PERFORMANCE EVALUATION
GMWHsO.
FULINPsO.
FANMWHsO.
DO 97 J=l>3
64
-------
oi2o;ic
01210 tF(PCTHRSU) >97»97»102
oi2?oc
01230 10? no 9'5 i=i»2?
oi24oc
01250C ANNUAL HOURS OF OPERATION AT GIVEN OPERATING CONDITION
01260C
01270 OHRSr(TDUR(I)/100.)*
01350C
01 360 GTKW=R72.421*PCTLOD(J)+(13.5-2.58527*PCTLOD(J) ) *T ( I ) -4186.6
01370C
013ROC THROTTLE STEAM ENTHALPY (BTU/LB). THROTTLE STEAM FLOW (LB/HR) AND
01390C STEAM TURBINE-GENFRATOR OUTPUT (KW>
0 1 U 1 n TSH= 1 231 . 5+ 1 . 77«i*PCTLOD ( J ) + ( 0 . 264-0 .00 U66*PCTLOD ( J ) ) *T ( I )
01420C
01430 STGOd )=TLU(OBP(I»J) >BP.STGOUT( 1 » 1 ) >27)
IDS
01460 103 TSF=]900 i.i.
01470 STGKWzSTGO(l)
014ROC
01490 IF(T(I)-R9.)10!i
nisnoc
OlfSIO 100 TSFrl74745.+250.26*T(I>
01520 GO TO 105
01530C
0 1540 1 04 TSF=lfl60 . 6?*PCTLOD ( J ) + ( 1 5fl. 71+0 . 0204*PCTLOD ( J ) ) *T ( I ) -13310 .
01560 105 STGO(2)=TLU(OBP(I»J) » BP»STGOUT( 1 >2) »27)
01570 DELKW=STGO(1)-STGO(2)
0 1 5RO STGKWrSTGO (!)-(( 1900 .1 ' ,-TSF) /2000!1. ) *DELKW
01590C
0160f, 1.01 STGKWC=STGKW-MTSF*(TSH-1420.)/3413.)
01610C
01620C CUMULATIVE GROSS GENfRATION (MWH)
01630C
0164(1 GMWH=GMWH+(GTKW+STGKWC)*OHRS/100:i.
01650C
01660C CUMULATIVE FAN ENERGY (MWH) REQUIREMENTS AS",UMING 90 PERCENT FAN
01670C MOTOR FFr-ICIENCY
016ftOC
0 1 690 F ANMWHsFANMWH* ( F AN8HP ( I , J ) *0 . 746/0 . 9 ) *OHRS/1 000 .
0170. C
01710 99 CONTINUE
01720 97 CONTINUE
01730C
01740C ANNUAL AUXILIARY ENERGY REQUIREMENTS (FANS PLUS
01750C SUPPLEMENTAL AUXILIARY COOLING SYSTEM) AND ANNUAL NET GENERATION
01760C (MWH)
01770C
0 1 7flO AUXMWH=FANMWH+ ( SEHP*0 . 746/0 . 9 ) *AOPHRS/1000 .
01790 ANNMWHsGMWH-AUXMWH
65
-------
oiaooc
018) OC
01820C
01830
01850
oiflftnc
01870
01880
01890+
01900+
01910+
01920+
01930+
019UO+
01950+
01960+
01970+
01980+
01990+
02000+
02010+
020?0+
02030C
02050C
02060
02070C
020SOC
02090C
02100C
02110
02120C
02130
OUTPUT HEADINGS
ITOF=765fiB
PRINT 1003*ITOF
1003 FORMAT(R2)
PRINT 1000»APLFAC
1000 FORMAT(10/«mXDEVALUATION OF BRAINTREE COMBINED CYCLE PLANT*
//51X»*WITH 6EA AIR-COOLED CONDENSER*»5/^6Xf*ANNUAL PLANT*
* LOAD FACTOR =*»F6.1»* PERCENT*»3/8X»*ANNUAL*f15Xr
*UNIT* » 5X.*GROSS* » 5X » *ANNUAL* » 5X » *NET* » 6X»*ANNUAL*»fX f
*ANNUAL*»l«*X»*ANNUAL*»14Xf* TOTAL */8X»*FIXED-*»5Xr*UNIT*
»5X t *MAKEUP* t ^X r *ANNUAL*»3X»* AUXILIAR Y*»2X»*ANNUAL*»«»X,
•MAKEUP*»3X»*CAPITAL* 14X»*ANNUAL*»UKt*MAKEUP*»UK»*TOTAL*»
5X»*BUSRAR*/ftX»*CHARGE*»5X»*FUEL* r 6X t*WATER*»4X»*GENER-*»
4X t *ENERGY*»4X»*GENER-*»4X > *WATER*»4X r *AND 0+M* f 5X t*FUEL* t
5X»*WATER* r 5X > *ANNUAL*»4X»*ENERGY*/9X»*RATE*»6X t*COSTS*»
5X»*COSTS*^X»*ATION*»«*X»*REQUIRED*»3X»*ATION*rfX»
*REQUIRED*»3X»*COSTS*»5X»*COSTS*»5X»*COSTS*»5X > *COSTS*,5X r
*COSTS*//8X»*PERCENT*»3X>**/MMBTU*>1X»**/1000 GAL*»3X».
*MWH*»7X»*MWH* >7Xr *MMH* » 5X»*1000 GAL* 15X»*$* > 9X,*$* > 9X»
*$*,9X»*S*»6X»*MILLS/KWH*/6X»12(* *))
ANNUAL AND BUSBAR COST EVALUATION
D.O 9R M=1»NFCR
ANMUAL CAPITAL COSTS INCLUDING 1.0 PERCENT FOR OPERATION AND
MAINTENANCE
ANNCAP=CAPCST*((AFCR(M)+1.0)/100.)
HO 98 Nrl»NUFC
02150C
021AOC
02170
02180C
02190
02200C
022)OC
022''OC
02230
02P40C
02250C
02260C
02?70C
02280
02290
02300C
02310C
02320C
02330
023UO+
023FSO 1
02360+
02370C
02380
BUSBAR ENERGY PRODUCTION COSTS
ANNUAL PLANT FUEL COST
ANNFUL=FULINP*UFC(N)
DO 98 L=1»NMWC
ANNUAL MAKEUP WATER COSTS
ANNMWC=ANNMWR*UMWC(L >
TOTAL ANNUAL COSTS AND TOTAL
UMWC(L)>GMWH»AUXMWH»ANNMWH»ANNMWR*
ANNC AP, ANNFUL t ANNMWC»TOT ANN t BUSBAR
00) FORMAT(/F13.1»F10.2»F9.2»F12.0pF9.0»FH.OrF9.0»2F11.0»FR.O»
F12.0.F9.3)
9fl CONTINUE
-------
02<*DH CALL DATER(IDATE)
02U10 PRINT 1002»IDATE
02<*?0 100? FORMAT(//117X»A9)
02U30C
02UUO PRINT 1003* ITOF
02«»50 STOP
02U60 END
02U70C
02«*flO FUNCTION TLU(X*XT> YT»NT)
02U90C
0250HC THIS IS A FOUR-POINT LAGRANGIAN INTERPOLATION TABLE LOOK-UP
02510C ROUTINE
02520C
02530 DIMENSION XT (NT) , YT (NT)
02550C DETERMINE IF INDEPENDENT VARIABLE IS WITHIN RANGE OF TABULATED
025102»103
02ASOC DETERMINE POSITION OF INDEPENDENT VARIABLE IN ASCENDING ARKAY
02AfiOC
02670 102 DO 99 irl.NT
02ftflO IF(X-XTd) >105»10«M99
02690 99 CONTINUE
02700C
0271 OC DETERMINE POSITION OF INDEPENDENT VARIABLE IN DESCENDING ARiiAY
02720C
02730 103 DO 9fl 1=1 > NT
027^0 IF(X-XTd) )9fl»101»105
02750 9fl CONTINUE
02760C
02770C IF INDEPENDENT VARIABLE IS EQUAL TO TABULATED VALUE* SET FUNCTION
027flOC EQUAL TO CORRESPONDING VALUE OF DEPENDENT VARIABLE
02790C
02flOO 104 TLUsYT(I)
02810C
02fl?0 RETURN
02S30C j
02ft*»OC IF INDEPENDENT VARIABLE IS BETWEEN FIRST TWO OR LAST TWO
02fl5flC TABULATED VALUES* ADJUST INDEX TO OBTAIN FOUR POINTS FOR
02fl60C INTERPOLATION
02H70C
02ftflO 105 IF(I-2)106»106»in7
02fl90 10A 1=1+1
02900 SO TO 108
02910 107 IF(I-NT)108» 109*109
02920 109 1=1-1
02930C
02940C DETERMINE FUNCTION VALUE USING FOUR-POINT LAGRANGIAN
029SOC INTERPOLATION
029AOC
02970 10« Xl=XT(I-2)
029AO X2=XT(I-1)
02990 X3=XT(I)
67
-------
0300 I
03010C
03020
03030+
03040+
03050+
03060C
03070
030AOC
03090
03100
03110+
03120C
03130
03140
03150
X*»=XT(I+1)
TLU=(X-X2)*(X-X3)*(X-Xi»)/<(Xl-X2)*(Xl-X3)*(Xl-X«f))*YT(I-2)
+ (X-X1)*(X-X3)*(X-X<*) / ( (X2-X1)*(X2-X3)* (X2*-X4) )*YT(1-1)
+
-------
TECHNICAL REPORT DATA
(Please read Imtfuc lions on the reverse before completing}
1. REPORT NO.
EPA-600/2-76-178
2.
3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
Feasibility Study for a Direct, Air-Cooled
Condensation System ,
5. REPORT DATE
July 1976
6. PERFORMING ORGANIZATION CODE
7. AUTHOH(S)
Michael D. Henderson
8. PERFORMING ORGANIZATION REPORT NO
9. PERFORMING ORGANIZATION NAME AND ADDRESS
R. W. Beck and Associates
400 Prudential Plaza
Denver, Colorado 80202
10. PROGRAM ELEMENT NO.
1BB392; ROAP 21AZU-034
11. CONTRACT/GRANT NO.
R803207-01
12. SPONSORING AGENCY NAME AND ADDRESS
EPA, Office of Research and Development
Industrial Environmental Research Laboratory
Research Triangle Park, NC 27711
13. TYPE OF REPORT AND PERIOD COVERED
Final; Through 12/75
14. SPONSORING AGENCY CODE
EPA-ORD
15. SUPPLEMENTARY NOTES Project officer for this report is J. P. Chasse, EPA Environmental
Research Center, Corvallis, OR 97330 (FTS 420-4718).
e. ABSTRACT The rep0rt gives results of an investigation of the feasibility of utilizing
direct, air-cooled condensation systems in coastal environments. Particular atten-
tion was devoted to the prevention of corrosion of external surfaces of fintubes, of
coil freezing, and of excessive noise. Manufacturers were contacted to determine
the extent of their experience in providing this equipment. Owners and operators of
dry towers were visited on-site to determine if the equipment can operate satisfac-
torily under a wide range of load and atmospheric conditions. Performance was
also evaluated for the dry tower associated with an 85-MW combined-cycle unit
under construction for the Braintree (Massachusetts) Electric Light Department.
7.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
Pollution
*Air Coolers
* Cooling Systems
Feasibility
Thermal Power Plants
Performance
*Noise (Sound)
*Freezing
*Corrosion
Pollution Control
*Dry Cooling Tower
*Vacuum Steam Con-
denser
c. COSATI Field/Group
13B
13A
14A
10B
14D
20A
07D
8. DISTRIBUTION STATEMENT
Unlimited
19. SECURITY CLASS (ThisReport}
Unclassified
21. NO. OF PAGES
75
20. SECURITY CLASS (Thispage}
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
69
------- |