United States Office of Water and SW 176C.17
Environmental Protection Waste Management October 1979
Agency Washington, D.C. 20460
Solid Waste
&EPA European Refuse Fired
Energy Systems
Evaluation of Design Practices
Volume 17
-------
Pie-publication iA&ue. jJoA. EPA JU.b>uvu. tnip lapotit (SW-J76C.I7) duActUbu Monk peA&o>une.d
the, O^ice. o& Solid Woite andeA contract no. 6B-01-4376
and it, ^.ep/iodaced at, A.ece^.ved ^fiom the. contxactoi.
The. £indi.ngA should be. att^ibute.d to tkn
and not to the, O&fiice. o& Sotid Watte..
Copies will be available from the
National Technical Information Service
U.S. Department of Commerce
Springfield, VA 22161
Volume 17
U.S. ENVIRONMENTAL PROTECTION AGENCY
1979
-------
This report was prepared by Battelle Laboratories, Columbus, Ohio,
under contract no. 68-01-4376.
Publication does not signify that the contents necessarily reflect the
views and policies of the U.S. Environmental Protection Agency, nor does
mention of commercial products constitute endorsement by the U.S.
Government.
An environmental protection publication (SW-176c.l7) in the solid waste
management series.
U.8.
-------
TRIP REPORT
to
BADEN-BRUGG PLANT
TURGI, AARGAU, SWITZERLAND
on the contract
EVALUATION OF EUROPEAN
REFUSE FIRED STEAM GENERATOR
DESIGN PRACTICES
to
U.S. ENVIRONMENTAL PROTECTION AGENCY
September, 1977
EPA-Contract Number: 68-01-4376
Battelle Project Number: G-6590
EPA-RFP Number: WA-76-B146
by
Richard Engdahl and Philip Beltz
BATTELLE
Columbus Laboratories
505 King Avenue
Columbus, Ohio 43201
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ORGANIZATION
The four volumes and 15 trip reports are organized the the
following fashion:
VOLUME I
A EXECUTIVE SUMMARY
B INVENTORY OF WASTE-TO-ENERGY PLANTS
C DESCRIPTION OF COMMUNITIES VISITED
D SEPARABLE'WASTE STREAMS
E REFUSE COLLECTION AND TRANSFER STATIONS
F COMPOSITION OF REFUSE
G HEATING VALUE OF REFUSE
H REFUSE GENERATION AND BURNING RATES PER PERSON
I DEVELOPMENT OF VISITED SYSTEMS
VOLUME II
J TOTAL OPERATING SYSTEM RESULTS
K ENERGY UTILIZATION
L ECONOMICS AND FINANCE
M OWNERSHIP, ORGANIZATION, PERSONNEL AND TRAINING
VOLUME III
P REFUSE HANDLING
Q GRATES AND PRIMARY AIR
R ASH HANDLING AND RECOVERY
S FURNACE WALL
T SECONDARY (OVERFIRE) AIR
VOLUME IV
U BOILERS
V SUPPLEMENTARY CO-FIRING WITH OIL, WASTE OIL AND SOLVENTS
W CO-DISPOSAL OF REFUSE AND SEWAGE SLUDGE
^
X AIR POLLUTION CONTROL
Y START-UP AND SHUT-DOWN
Z APPENDIX
-------
TABLE OF CONTENTS
Page
ACKNOWLEDGEMENT i
PREFACE ii
SUMMARY ill
STATISTICAL SUMMARY 1
Baden-Brugg Plant 1
OVERALL SCHEMATIC 6
DEVELOPMENT OF THE SYSTEM 8
COMMUNITY DESCRIPTION 9
Geography 9
Government and Industry 12
SOLID WASTE PRACTICES 13
Solid Waste Generation 13
Solid Waste Collection Activities 16
Solid Waste Disposal 16
TOTAL OPERATING SYSTEM 18
PLANT ARCHITECTURE AND AESTHETIC ACCEPTABILITY 18
REFUSE-FIRED STEAM GENERATOR EQUIPMENT 20
Furnace Hopper and Feeder 25
Burning Grate 26
Furnace Wall (Combustion and First Pass Radiation Chambers) . 29
Superheater 33
Boiler (Convection Section) 36
Boiler (Overall) 36
Economizer 37
-------
TABLE OF CONTENTS
(Continued)
Page
Heat Release Rate 38
Plant Operation 38
Boiler Water Treatment 40
Primary Air Supply 41
Secondary Air 42
CO-FIRING EQUIPMENT 44
Tertiary Air 47
Energy Utilization Equipment 52
POLLUTION CONTROL EQUIPMENT 54
Wastewater Discharge 56
Stack Construction 57
Pollution Control Assessment 58
Noises 60
PERSONNEL AND MANAGEMENT 60
Energy Marketing 62
ECONOMICS 63
Capital Investment 63
Operating Costs ..... 64
FINANCE 66
•
LIST OF TABLES
Table 2-1. Waste Categories and Rates at Baden-Brugg For 1975-76 . 15
Table 2-2. Energy Generation Rates at Baden-Brugg For 1975 and
1976 19
-------
LIST OF TABLES
(Continued)
Page
Table 2-3. Baden-Brugg Weekly Operating Summary May 2 to July 4,
1976 39
Table 2-4. Plant Income for 1975 and 1976 65
LIST OF FIGURES
Figure 2-1. Map of Baden-Brugg Plant 7
Figure 2-2. View of Baden-Brugg 200 Tonne Per Day Plant From the
Adjacent Sewage Treatment Plant Property 10
Figure 2-3. Area in Aargau Canton Served by Baden-Brugg Plant ... 11
Figure 2-4. Waste Received and Electricity Produced at Baden-Brugg
Since Startup 14
Figure 2-5. Tipping Area, Scale Room, and Office Entrance at Baden-
Brugg Plant 21
Figure 2-6. Truck Delivering Waste to the Pit at Baden-Brugg. The
Pit Doors are Hydraulically Opened 22
Figure 2-7. Crane Operator, Cranes and Grabs Above Pit 23
Figure 2-8. An Example of the Albert! Fonsar Step Grate System As-
sembled at the Factory 27
Figure 2-9. Baden-Brugg Furnace Grates 28
Figure 2-10. Cross-Section of Baden-Brugg Plant 30
Figure 2-11. Hr. B. Lochliger, Asst. Pt. Mgr., Holding Steel
Reinforcing Coil for Tube-Covering Molded Refractory . 32
Figure 2-12. Baden-Brugg Ruptured First Row Superheater Tube .... 34
Figure 2-13. Baden-Brugg Half Shields for Clamping on Superheater
Leading Face 35
Figure 2-14. Secondary Air Jets in the Rear Wall 43
Figure 2-15. Oil Burner on Side of and Toward Rear of Furnace for
Firing of Waste Oil 45
Figure 2-16. Cologne, W. Germany Hospital Waste Incinerator with
Sidewall Oil Burner 46
-------
LIST OF FIGURES
(Continued)
Figure 2-17. Proposed Revision of Sidewalls Incorporating Air-
Cooled, Cast-iron, Kunstler Blocks 48
Figure 2-18. Sketch of Air Flows to Furnace 49
Figure 2-19. Widmer & Ernst Photo of Man applying Kunstler Air-
Cooled Wall Blocks 50
Figure 2-20. Wall of Furnace No. at Baden-Brugg Modified with
Kunstler Air-Cooled Wall Blocks 51
Figure 2-21. Schematic Diagram of Thermal and Electrical Systems . 53
-------
ACKNOWLEGEMENT
The Battelle investigators are pleased to acknowledge the very
"competent, energetic and generous assistance which we received from the
following.
E. Luedi, Plant Manager
Mr. Lochliger, Assistant Plant Manager
Herr Zumbilhl, President, Zweckverband Kericht-Verwertung Region
Baden-Brugg
Peter Nold, Engineer, Widmer & Ernst
Theodor Ernst, President Widmer & Ernst
Robert Hardy, U.S Representative, Widmer & Ernst
-------
ii
PREFACE
This trip report is one of a series of 15 trip reports on
European waste-to-energy systems prepared for the U.S. Environmental
Protection Agency. The overall objective of this investigation is to
describe and analyze European plants in such ways that the essential
factors in their successful operation can be interpreted and applied
in various U.S. communities. The plants visited are considered from
the standpoint of environment, economics and technology.
The material in this report has been carefully reviewed by the
European grate or boiler manufacturers and respective American licensees.
Nevertheless, Battelle Columbus Laboratories maintains ultimate responsi-
bility for the report content. The opinions set forth in this report are
those .of the Battelle staff members and are not to be considered by EPA
policy.
The intent of the report is to.provide decision making in-
formation. The reader is thus cautioned against believing that there is
enough information to design a system. Some proprietary information has
been deleted at the request of vendors. While the contents are detailed,
they represent only the tip of the iceberg of knowledge necessary to de-
velop a reliable, economical and environmentally beneficial system.
The selection of particular plants to visit was made by Battelle,
the American licensees, the European grate manufacturers, and EPA. Pur-
posely, the sampling is skewed to the "better" plants that are models of
what the parties would like to develop in America. Some plants were selected
because many features envolved at that plant. Others were chosen because
of strong American interest in co-disposal of refuse and sewage sludge.
The four volumes plus the trip reports for the 15 European
plants are available through The National Technical Information Service,
Springfield, Virginia 22161. NTIS numbers for the volumes and ordering
information are contained in the back of this publication. Of the 19
volumes only the Executive Summary and Inventory have been prepared for
wide distribution.
-------
iii
SUMMARY
This plant has been a logical result of the environmentally
conscious planning begun in 1956 by two communities in a highly industrialized
but nevertheless very clean and picturesque area in northern Switzerland.
The plant is small and the design approach was conventional, using about the
best of the known available technology at the time for waste-to-energy
systems. As a result, its operational problems have been minor and it is
achieving its goal — a highly acceptable operation environmentally with
acceptable costs for disposal of community wastes while recovering some
useful energy in the process.
The plant was preceded by a compost plant which began operation
in June 1961, but by 1964, it became apparent that the plant could not handle
a growing load of waste. Expansion of the plant would have overloaded the
available markets for compost hence, after further study, a loan of 16.5
million Swiss Francs was obtained in May 1966, to build a 2-furnace heat-
recovery plant. Steady operation began November 20, 1970.
There have been no major operational problems. Corrosion of a
few of the water-tube-wall tubes and superheater have been caused by a com-
bination of high gas velocities, inadequate gas mixing and excessive soot-
blower concentration on a few tubes. These deficiencies have been or are
being corrected by tube cladding, shielding and by improved mixing through
better air distribution.
The net burning cost after considering operating, maintenance,
repairs, financing and income from thermal and electrical output is now
averaging about 50.23 Swiss Francs/tonne ($18.37/ton based on 2.48 Fr/$).
-------
STATISTICAL SUMMARY
Baden-Brugg Plant
Community description:
Area (square kilometers)
Population (number of people)
Key terrain feature
100
141,000
mountainous
Solid waste practices:
Total waste generated per day (tonnes/day)
Waste generation rate (Kg/person/yr)
Lower heating value of waste (Kcal/kg)
Collection period (days/week)
Cost of collection (local currency/tonne)
Use of transfer and/or pretreatment (yes or no)
Distance from generation centroid to:
Local landfill (kilometers)
Refuse fired steam generator (kilometers)
Waste type input to system
Cofiring of sewage sludge (yes or no)
124.7 (365-day yr)
322
2600
5
50 SFr
No
Landfill 30 km away but
not used
mixed municipal refuse
No
Development of the system:
Date operation began (year)
November 1970
Plant architecture:
Material of exterior construction
Stack height (meters)
Concrete
85.6
Refuse fired steam generator equipment:
Mass burning (yes or no)
Waste conditions into feed chute:
Moisture (percent)
Lower heating value (Kcal/kg)
Volume burned:
Capacity per furnace (tonnes/day)
Number of furnaces constructed (number)
Yes
Approximately 25 percent
2600
100
2
-------
Capacity per system (tonnes/day)
Actual per furnace (tonnes/day)
Number of furnaces normally operating (number)
Actual per system (tonnes/day)
Use auxiliary reduction equipment (yes or no)
Pit capacity level full:
(Tonnes)
(m3)
Crane capacity:
(tonnes)
(m3)
Feeder drive method
Burning grate:
Manufacturer
Type
Number of sections (number)
Length overall (m)
Width overall (m)
Primary air-max
3
Secondary air-overfire air-max (m /riiin)
Furnace volume (m )
Furnace wall tube diameter (cm)
2
Furnace heating surface (m )
Auxiliary fuel capability (yes or no)
Use of superheater (yes or no)
Boiler
Manufacturer
Type
Number of boiler passes (number)
Steam production per boiler (t/hr max)
Total plant steam production (t/hr max)
Steam temperature ( C)
Steam pressure (atm)
200
80-100
2
160-200 (5 days/week)
No
2600
5t (2 cranes)
2
Hydraulic
Alberti-Fcnsar
Stepped reciprocating
7 steps long
7.5
2.5
66
7.61
892
Yes
Yes
Alberti-Fonsar
Natural circ. water tube
3
12.5
25.0
400
40
-------
Use of economizer (yes or no)
Use of air preheater (yes or no)
Use Of flue gas reheater (yes or no)
Cofire (fuel or waste) input
Use of electricity generator (yes or no)
Type of turbine
Number of turbines (number)
•
Steam consumption (t/hr)
Electrical production capacity per turbine (MW)
Total electrical production capacity (MW)
2
Turbine back pressure (kg/m )
User of electricity ("Internal" and/or "External")
Yes
No
No
No
Yes
Condensing
I
25 (on completion)
5.2
5.2
Internal, external
Energy utilization:
Medium of energy transfer
Temperature of medium ( C)
Population receiving energy (number)
2
Pressure of medium (kg/ra )
Energy return medium
Steam, hot water
90-70 (water)
3.0/10.0
Water
Pollution control:
Air:
Furnace exit conditions
Gas flow rate (m /hr)
Furnace exit loading (mg/Nm )
64,000 (max.)
at 7% C02
-------
4
Equipments
Mechanical cyclone collector (yes or no) Yes
Electrostatic precipitator (yes or no) Yes
Manufacturer Elex
Inlet loading on precipitator (rag/Nm )
Exit - leading on precipitator (mg/Nm ) iQO at 7% C02
Legislative requirement (rag/Nm ) 100 at 7^ CQ
Scrubber (yes or no) No
Inlet loading:
H Cl (mg/Nm3) N.A.
H F (mg/Nm3) N.A.
Exit loading:
H Cl (mg/Nm3)
H F (mg/Nm3) N A>
Legislative requirements (mg/Nm ) N.A.
Other air pollution control equipment (yes or no) No
Water:
Total volume of waste water (liters/hr)
Ash:
Volume of ash (tonnes/day) Approx. 57 (wet)
Volume of metal recovered (tonnes/day)
-------
5 and 6
OVERALL SCHEMATIC
Figure 2-1 shows the arrangement of the Baden-Brugg waste-to-
energy plant.
-------
Railroad
to sewage plant/
0 5 10 15 20 25
1. Weigh scale
2. Scale office
3. Waste oil
4. Tipping area
5. Refuse bunker
6. Furnace room
7. Feedwater tank
8. Shop
9. Turbogenerator
10. Control room
11. Electrical controls
12. Electrostatic precipitator
13. Mechanical dust collector
14. Chimney
15. Reservoir
16. Garage
FIGURE 2-1. MAP OF BADEN-BRUGG PLANT
(Courtesy of Baden-Brugg Waste Management Association)
-------
DEVELOPMENT OF THE SYSTEM
In 1956 the separated communities of Baden-Brugg began a study of
alternate methods for solving their growing solid waste problems (see Figure
2). This study envisioned by 1985 a population of 77,000 and a solid waste
production of 20,000 tonnes (22,000 tons) per year. A common waste processing
plant was recommended for the 2 regions. A compost plant at Turgi was
recommended as a first step to be followed by an incinerator when needed.
In 1959 the Zweckverband Kehricht-Verwertung Region Baden-Brugg
(Baden-Brugg Waste Management Association) was formed and included 8 other
adjacent communities shown in Figure 2. The compost plant was begun in April
1960 and began operation in June 1961. However, this plant could not handle
bulky and industrial waste. Also in 1964 it became apparent that the amount
of waste was increasing and the population served was then up to 120,000.
Preliminary plans envisioned an incinerator using 2 furnaces, each handling
100 tonnes (110 tons) per day based on refuse having a lower heating value
of 2500 kcal/kg (4500 Btu/lb)[10,468 kJ/kg]. The local firm of Motor-
Columbus, AG was engaged to study the feasibility of the plant which was to
include heat recovery by steam and power generation plus the best available
exhaust gas cleaning method. On the basis of this study in May 1966 a loan
was obtained of 16.5 million Swiss Francs ($3.81 million at the 1966 exchange
rate of 4.33). In the Spring of 1967 a boiler-furnace plant contract was
agreed to with Alberti-Fonsar of Milan and at the end of 1967 a contract
for the steam turbogenerator was given to the Baden firm of Brown-Boveri
Company. Excavations were begun in February 1968, acceptance tests were
begun in February 1970, the Association gave provisional acceptance in June
1970 and steady operation began November 20, 1970.
During the course of the development of the plant some opposition
was voiced in die local press, partly because of expectations of air quality
impacts on the hills across the river. The stack height was specified in
the original RFP.
There were 5 bids, all very similar in price.
-------
COMMUNITY DESCRIPTION
Geography
As shown in Figure 2-2, the plant is located in a narrow valley.
The Limmatt River is on one side and a 2-track electric railroad is
immediately against the other side of the plant. There are a few residences
to the west but no concentrated landuse in the immediate vicinity. The
population served is about 140,000.
A sewage treatment plant is located just North of the plant.
Then just South of the plant, a privately operated hazardous waste treat-
ment processes chemical wastes (arsenic, etc.) from all of Northern
Switzerland. This is yet another example of the "Sanitary Park" so preva-
lent in Europe.
The area served (see Figure 2-3) is approximately 100 sq km (38.7
sq. mi.), about 18 km (11 mi) long and 5.5 km (3.4 mi) wide. There are
56 villages in the area. About 12 of these comprise original members of the
Association, 44 other communities participate by sending waste.
-------
10
FIGURE 2-2. VIEW OF BADEN-BRUGG 200 TONNE PER DAY PLANT FROM
THE ADJACENT SEWAGE TREATMENT PLANT PROPERTY
(Courtesy Baden-Brugg Waste Management Association)
-------
11
Standort der Anlage
1 100000
FIGURE 2-3. AREA IN AARGAU CANTON SERVED BY BADEN BRUGG PLANT
-------
12
Government and Industry
Many industrial plants are located in the area served by this plant.
The world headquarters of the Brown-Boveri Co., is in Baden very near to the
plant. The engineering firm of Motor-Columbus is also in Baden.
-------
13
SOLID WASTE PRACTICES
Solid Waste Generation
In Figure 2-4, it can be observed that the population served has
increased by 40 percent since the plant started in 1970, because more
communities joined. Also, the per capita waste generation rate increased.
Thus the total waste collected increased 56 percent between 1971 and 1976.
However, the rate of increase has been dropping since 1973.
Table 2-1 from the plant statistical statement, shows the waste
categories and amounts processed in 1975 and 1976.
-------
Waste received kg/per inhabitant-year
—-:-(—:— f-rppf—T-r r -I...) : j:
>* -jj> •_ ftt ; to jU vu vjrt vU vU.
in . -tJ <» «p o *-• to W
> o o.oo o 0,0 o
i j ' • ; , j , j , j ' i Waste received, tonnes /year
Combined population served xlOJ ^ K, vi* vii v* via \ji i- *.
\
4
Electricity produced
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•
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FIGURE 2-4. WASTE RECEIVED AND ELECTRICITY PRODUCED AT BADEN-BRUGG SINCE STARTUP
-------
15
TABLE 2-1. WASTE CATEGORIES AND RATES AT BADEN-BRUGG
FOR 1975-76 (FROM PLANT STATISTICAL STATEMENT)
Statistical Statement
Population on December 31
Waste input:
Household waste only
Bulky waste only
Household mixed with bulky waste
Industrial waste
Processed Waste:
Refuse
Waste.oil, oil sludge, emulsions
Wet residue weight
Wet residue related to refuse input
Refuse processed per day
Refuse per inhabitant-year
including industrial
Refuse per inhabitant-year
without industrial
tonne
t
t
t
t
t
t
Z
Tonnes per
working day
kg/person-year
kg/person-year
1976
139,300
1,534.06
1,934.73
33,988.17
4,235.99
41,692.95
39,300.00
15,177.90
38.62
160.35
297.4
267.0
1975
141,000
2,633.72
2,088.33
32.008.5J
4,152.17
40,882.79
38,700.00
14,613.86
37.76
157.24
287.1
260.6
-------
16 & 17
Solid Waste Collection Activities
About 35 percent of the waste glass generated is recycled through
a pickup system for special containers at each residence. Some paper is
gathered by Scouts.
There is no use of transfer stations nor of waste pretreatment.
About 60 public and 40 private collection vehicles bring refuse
to eht plant 5 hours per day, 5 days per week. Each community is charged for
the weight delivered by its trucks. Each family served pays 50-85 Sw Fr
($20-34) per year for collection.
Solid Waste Disposal
The grate residue is hauled 8 km, (5 miles) to a community
landfill having the following characteristics:
type of landfill: quarry
ownership: community Wiirenlingen
costs (late 1977): 10.80 SF./m3 ($3.30/yd3 @ SF 2.5/$)
method of filling: truck plus levelling with caterpillar
frequency of cover: no cover
-------
18
TOTAL OPERATING SYSTEM
Table 2-2 from the plant statistical statement shows the energy
production figures for 1975 and 1976. The average plant evaporation rate
for 1976 was 2,26 tonne steam per tonne refuse. Assuming the average LHV
of the refuse was 2285 kcal/kg (9557 kJ/kg)[4113 Btu/lb] this corresponds
to an average steam generating efficiency of 55 percent.
The electrical energy produced averaged 440 kwh/tonne. This
corresponds to a generating efficiency of 16 percent.
The amount of thermal energy supplied to the adjacent plants
was small and was not recorded.
The volume reduction of the refuse was estimated to be about
85 percent. The weight reduction achieved is about 37-38 percent.
The plant, which began operation in November 1970, has had no
major shutdowns since the initial problems with tube wastage in 1973 after
11,000 hours operation. Normally, maintenance can be done during the
regular week-end shut-down. Every 6 months the plant is down for 1 week
for major overhaul.
Except for the routine downtime, operation was 99.1 percent of
the time in 1975 and 96.7 in 1976.
PLANT ARCHITECTURE AND
AESTHETIC ACCEPTABILITY
This small plant is formed basically of simple concrete forms
but is impressive and attractive as located adjacent to the sewage treat-
ment and Fairtec industrial waste treatment plants. These 2 small plants
are crowded together in the narrow valley between a double-track railroad
and the Limmat River but the combined appearance is good and not severely
crowded.
-------
19
TABLE 2-2 ENERGY GENERATION RATES AT BADEN-BRUGG FOR 1975 AND 1976
(FROM PLANT STATISTICAL STATEMENT)
1975
1976
Operating time of both furnaces
Operating time of turbine
Average furnace capacity
Average boiler capacity
Average turbine capacity
Average coefficient of evaporation
Average heat value of waste
Electrical energy per tonne
of waste
Total electrical production
Electricity supplied to AEW, ARA, Fairtec
ARA, Fairtec
Electricity internally generated
and used
Electricity purchased from AEW
Total internally used electricity
(without losses)
Electricity consumption per tonne
of refuse
h/ year
"' year
mt/h
mt/h
kw
t/t
kcal/kg
kwh/mt
kwh x 106
-C fi
kwh x 10
kwh x 10
kwh x 10
6
kwh x 10
kwh/mt
10,598
6,132
3.72
8.41
2,833.2
2.26
2,285
440
17.37
14.85
2.52
0.20
2.72
68.91
9,750
5,467
3.97
8.60
2,943.0
2.16
2,165
415
16.09
13.79
2.30
0.20
2.50
64.44
-------
20
REFUSE-FIRED STEAM GENERATOR EQUIPMENT
Both public and private trucks deliver refuse to the steam-
generating plant 5 days per week. They are weighed on a Toledo scale
which prints total, tare and net weights on a card. The scale is inspected
once per year. An increasing amount of waste oil is received. In 1976
the waste oil totalled 172 tons for the year. Figure 2-5 shows the tipping
area, waste oil receiving scale and indoor weighing station.
Originally the plant was equipped with a Hazemag hammermill shredder
adjacent to the refuse pit to break up bulky refuse. However, in 1972 owing
to the need to replace the shredder bars and re-weld the hammers every 3
months, the receipt of bulky wastes was limited to a maximum size of one
meter. The homeowner is required to break up any objects larger than one
meter on a side or to send large metal objects directly to a scrap dealer.
The shredder is now operated only occasionally to assure that its working
parts are kept in operable condition.
Figure 2-6 shows a truck delivering a load. After each truck driver
delivers a load to the pit he is expected to clean his dumping area. The crane
operator can direct truck drivers to alternate tipping bays by the red and greei
lights above the truck entrance (see Circle in Figure 2-5).
3
The refuse pit storage capacity when level-full is 2600m . Assuming
3 3
a stored refuse density of 0.4 tonnes/m (560 Ib/yd ) its storage volume
would be 1040 tonnes (945 tons), or about a 5-day fuel supply at capacity
operation. The pit is 23.4m (76.7 ft) long, 14.1m (45.3 ft) deep and 8.4m
(27.6 ft wide). Fires in the pit can be controlled by means of overhead
sprinklers.
The pit is equipped with 2 cranes built by Mars-Uto of 5-tonne
3 3
capacity each. Each is equipped with a 2m (2.6 yd ) polyp or orange-peel
type of grab. The weight of each crane load can be observed by the crane
operator on a digital read-out actuated by a strain gage on the crane cable.
The operator, whose pulpit is at the end of the pit, records this weight
reading manually. Figure 2-7 shows the operator and two crane grabs.
An automatic crane stop is provided so that if the crane approaches
an open delivery door on the side of the pit the crane is prevented from
striking and damaging the open door.
-------
21
FIGURE 2-5. TIPPING AREA, SCALE ROOM, AND OFFICE ENTRANCE AT
BADEN-BRUGG PLANT (Courtesy Region of Baden-Brugg)
-------
"I 9
tiiii
FIGURE 2-6. TRUCK DELIVERING WASTE TO THE PIT AT BADEN-BRUGG.
THE PIT DOORS ARE HYDRAULICALLY OPENED.
(Courtesy Region of Baden-Brugg)
-------
FIGURE
CRANE OPERATOR, CRANE.S ArJD
(Courtesy Region of Baden-i
-------
24
The plant staff feel that it is beneficial to the operation to
mix and store the refuse in the pit for at least 48 hours for the following
advantages:
1. a more nearly homogeneous charge results
2. the material is more compact
3. fermentation raises the waste temperature which helps
slightly with ignition
4. moisture content is more uniform.
All of these factors contribute toward better furnace operation.
In 1978 it is planned to begin 7-day per week operation of the
plant.
-------
25
Furnace Hopper and Feeder
The top of each furnace hopper is Am (13.1 ft) square and the feed
chute is 2.5m by 1.5m (8.2 ft by 4.9 ft). The chute is not cooled but in-
sulated. If burnback into the hopper occurs it can be stopped by means
of a hinged insulated cover placed over the hopper. When large objects jam
the chutes a wood ram held by the grab is used to force the object downward.
A single level, hydraulically-driven ram feeder made by Hydron
feeds the refuse inward every 1.5 min. The length of stroke is 600mm (1.9 ft)
The speed of the motion is fixed. If something prevents the ram from with-
drawing from the furnace an alarm sounds. Reliability has been essentially
100 percent. There is no feeder redundancy. After 7 years operation the
cylinder on the drive has recently been replaced. The piston guide is
lubricated once per month.
Initially the feeder piston seal leaked. That defect was corrected.
The feeder plate was changed from cast iron to steel because early in the
operation, heavy objects falling from the feed chute broke the feeder plate.
-------
26
Burning Grate
Figure 2-8 shows an example of the Alberti-Fonsar GMP-7 stepped
grate. At Baden-Brugg it is made up of 6 sections which provides an average
fuel bed slope of about 24 . It was fabricated in Italy by the Fonderie e'Officine
di Saronne S.p.A. using a grate material which is 25-30% chromium, 4% nickel,
0.5% manganese and 0.8% silicon. The grate is made up of steps which alter-
nately are fixed and reciprocating. The reciprocating parts have a maximum
stroke of 380mm (15 in) with the normal stroke being 350mm (14 in) which
occurs about once every 2 minutes. As the upper step moves forward it tends
to tumble the burning refuse downward to the next step, thus providing gentle
agitation. Grate temperature can be monitored by the control room operator
from indicators connected to three thermocouples located under the grate.
The temperature is controlled to less than 400°C by control of primary air
flow and feed rate.
The grate sections were guaranteed for 16 months. The manufacturer
*
expects the grate to last 5 to 10 years. Some problem has been encountered
with pluggage of the air holes in the grate by fused aluminum and plastics.
When this happens, workmen wearing heavy wetted asbestos suits enter the
partially cooled chamber to remove or punch through the fused material in
the grate holes.
The grate residue is dropped when hot from the end of the grate
into a large concrete quench tank which appears as a shallow slag basin in
the lower part of Figure 2-10. At the deepest point, the water in the basin
is 1.7 m (5.57 ft) deep. Residues from the precipitator and boiler passes
are also dropped into this tank. The quenched residue settles to the bottom
of the tank from which it is removed continuously by a 12 m (39 ft) drag-
chain conveyor which drops it into a slag skip.
The manufacturer believes that they have since evolve, at other
plants a much better quench-tank removal device involving " piston-driven
swing gate which tends to compress the residue as it lifts it much more
nearly vertically otu of a much smaller, curved-bottom steel tank. As a
result, the discharged residue is said to have only 25 percent moisture as
against 40 percent from the system at this plant. The newer system also
costs less and produces less waste water.
The wet residue is trucked to a landfill for which the dump charge has been
o
SF, 43.5 per 7 m container, equivalent to SF 6.2 per m^ ($2.8/yd^). In late
1977 it was raised to SF 10.80/m3.
-------
27
FIGURE 2-8. AN EXAMPLE OF THE ALBERT1 FONSAR STEP GRATE SYSTEM ASSEMBLED
AT THE FACTORY (Courtesy of Widmer + Ernst (Alberti-Fonsar))
-------
28
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29
Furnace Wall (Combustion and
First Pass Radiation Chambers)
The main furnace is largely refractory walled. Only the sloping
rear wall of the furnace is water-cooled. Owing to successful experience
in other plants these two furnaces are in process of being modified to
incorporate air-cooling. The sidewalls of the furnace up to now have
consisted only of Plibrico Super AB plastic refractory ISO mm (6 in)
thick backed up by 250 mm (10 in) of high temperature calcium silicate
insulation plus a 4 mm steel casing. The front arch is similarly all
refractory except for a small water-cooled casting which protects the tpp-
front corner of the furnace from the abrasive action of the refuse as it
emerges from the feed chute into the furnace. A major portion of the
refractory wall near the grate will soon be replaced by cast iron, air-
cooled wall blocks developed by Kttnstler. These will also Introduce some
air formerly introduced by the original sidewall overfire (secondary) air
jets shown in three separate horizontal rows in Figure 2-10 about one meter
(39 in) above the grate. (See later section on tertiary air.)
As the combustion gases rise out of the partially cooled refractory
walled furnace they are accelerated into a tall* open, vertical, water-tube
walled boiler pass which is about 7 • (23 ft) tall, 2.5 m (8.2 ft) wide and
2 2
1.5 m (4.9 ft) deep. Thus its cross-sectional area is 3.75 m (40.2 ft ).
Assuming a uniform flow and a gas temperature entering this first pass of
about 1000 C (1832 F) and a gas flow rate of 5 kg/sec corresponding to 100 tonnes
per hr and approximately 100% excess air, the entering velocity would be about
5 m/sec (16.4 ft/sec). This is considered a high velocity and, because of the
eddies formed when the gases accelerate into this pass, this rather high
velocity may have been partly responsible for early failure of 9 wall tubes
in the lower part of this first pass.
As a result of those failures a 25 mm (1 in) silicon carbide covering
was added over the lower 5 m (16 ft) of these walls. However, this increased
the superheater outlet temperature 20 C (36 F). Hence in 1974, in Boiler No. 1
the height of this covering was reduced to only 1 m (3.28 ft). The silicon
carbide covering is not held in place by welded studs but by 20 mm dia steel
coils which are anchored to the tubes before being buried by the plastic
refractory covering. Since this coil-supported covering was applied there
have been no further failures of wall tubes. The wall covering now needs
-------
30
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31
patching about every 3 to 7 years. Although this steel coil support for the
refractory covering has apparently served well in this installation, the
manufacturer has since used the more conventional welded steel studs to sup-
port the refractory covering on the sloping rear wall of the main furnace.
Figure 2-11 shows a steel coil used to reinforce the refractory
coating on some wall tubes.
The manufacturer believes that the failure of 9 wall tubes was
caused primarily by reducing gases flowing against those tubes. The tube
material is C14UN15462-64, a typical carbon steel. They are 57 mm (2.24 in)
dia with 2.9 mm (0.11 in) wall thickness and are spaced 59 mm on centers.
(Regarding the subject of reducing gases see later section on Secondary Air.)
-------
32
FIGURE 2-11. MR. LOCHLIGER, ASSISTANT PLANT MANAGER, HOLDING STEEL
REINFORCING COIL FOR TUBE-COVERING MOLDED REFRACTORY
(Battelle Photo)
-------
33
Superheater
As the gases reach to the top of the first boiler pass they are
turned 180 degrees and then pass downward through the second water-tube
walled pass which contains The Superheater. It has a total heating sur-
face of 104 m2 (1119 ft2). Final steam temperature is 400 C (752 F). The
superheater tubes are vertical and are suspended from the top. They are
4 m (13 ft) long, 33.7 mm (1.32 in) dia. and are spaced on 120 mm (4.7 in)
centers. The superheater steel is 14% chromium, 3% molybdenum. At first
they were 2.9 mm (0.11 in) thick. Later the thickness was increased to
3.2 mm. Now they are 4 mm (0.15 in) thick. The final thick walled tubes
were installed in Boiler No. 1 in 1972 and in Boiler No. 2 in 1974.
Although the gas flow through the superheater is mainly parallel
flow, the horizontal entry of the gases into the superheater from the first
pass is actually cross flow. Thus the hot gas, at a temperature of 700 C
(1292 F) , carrying potentially erosive and corrosive flyash, impinges against
the 23 vertical superheater tubes in the first row. Initially this caused
some tube wastage and the first row of tubes was replaced in 1972. Figure 2-12
shows the longitudinal failure of a Baden-Brugg first row superheater tube.
Accordingly, in October 1973, after 11,290 hours of operation of Boiler No. 1,
half shields made of Sicromal (18-8); steel tubing (see Figure 2-13) were
clamped over the leading face of this first row only. Thicker walled super-
heater tubes have also been installed and additional 17,810 hours had been
achieved at the time of our visit on May 9, 1977. The shields must be replaced
about every 6000 hours. The plant management estimates that the present
superheaters will last 60,000 hrs .
Although steam-actuated soot blowers are available for cleaning ash
deposits from the superheater tubes they are not used because of the wide-
spread experience that soot blowers often accelerate tube wastage. These
superheaters are cleaned manually every 6 weeks, on weekends, by means of
compressed air nozzles which can be inserted through the access doors in the
wall of the superheater passage.
-------
34
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Boiler (Convection Section)
Referring again to Figure 2-10, the gases are flowing downward as they
leave the vertical superheater and then continue downward through a short open
water-tube-walled boiler section before they again are turned upward to enter
the boiler convection section and then the economizer. The boiler tubes are
inclined and consist of 2 banks of tubes, one above the other and surrounded
by water-tube walls on both sides.
Boiler (Overall)
The boilers, built by Alberti-Fonsar, are natural circulation type
built under the Eckrohr (corner tube) design licensed by Dr. Vorkauf of Berlin.
Their nominal steam flow rate is 13 tonnes/hr each (28,600 lb/hr) . The
steam pressure is 40 atm (40.53 bar) (588 psia), corresponding to a saturation
temperature of 150 C (302 F). Final superheated steam temperature is 400 C
(752 F). The total height of the boiler is 14 m( '+& ft) above the boiler
room floor. It is 3.7 m (12.1 ft) wide and 6.2 m (20.3 ft) deep.
The control of the refuse feed rate can be automatic from boiler
pressure. However, if this system results in the overheating of a temperature
sensor in the furnace an alarm is sounded, the control room operator
is under instructions to increase the flow of secondary air and to- reduce
the frequency of the grate motion and of the refuse feeder until the furnace
temperature indicator shows operation within a specified limit
-------
37
Economizer
The economizer is divided into 2 vertical passages. Both are
directly above the boiler convection section. The gases flow upward from
the convection section into the first economizer pass, then turn 180 degrees
and flow downward through the second pass. From there the gases go either
to the precipitator or to a bypass which leads directly to the chimney.
The economizer tubes are 33.7 mm (1.33 in) dia, 2.9 mm (0.114 in)
2 2
thick and both sections provide a total heating surface of 250 m (2691 ft ),
Each economizer pass is 3 m (9.84 ft) wide, 1.2 m (3.93 ft) deep and 4.1 m
(13.45 ft) high. The tubes are made of carbon steel (designated 35.8 II).
There have been no problems with economizer performance. Its
expected life is at least 20 years.
-------
38
Heat Release Rate
The nominal design loading of the grate is 238 kg/m2-h (48.8 lb/
ft2-h). For an LHV of 2600 kcal/kg (10,8861 kJ/kg) [4680 Btu/lb] this corres-
ponds to a heat release rate of 618,000 kcal/tn2-h (227,860 Btu/ft2-hr). This
is a very conservative full-load burning rate. Even at the maximum
furnace rating of 120 tonnes/day, if the grate is 7.5 m long and 2.5 m wide
(18..75 m2) (201.8 ft2), the burning rate is 266 kg/m2-h (54.6 Ib/ft2-h)
corresponding to a heat release rate of 691,600 kcal/m2-h (255,528 Btu/ft2-h).
These are also fairly conservative burning rates.
The volume of the main furnace plus the lower portion of the first
open boiler pass where combustion is completed was stated by the manufacturer
to total 66 m3 (2330 ft ). Considering the above heat release rates to
occur in this volume the corresponding volume heat release rate is 196,477
kcal/m3-h (22,080 Btu/ft3-h) which is a moderate rate.
Plant Operation
Table 2-3 is a summary of weekly plant operating data for the 9
weeks May 2, 1976 to July 4, 1976, provided from routine plant records.
The annual data similar to portions of this table will be discussed in later sections
of the report. It is shown together -here to facilitate the readers analysis of
processing and production rates. It is of interest that the total waste
burned never quite reached the nominal plant capacity for a 5-day week:
1000 tonnes. However, it nearly attained that rate in almost half of the
weeks. But the maximum power generation rate of 3.5 mw was well below the
nominal generator capacity of 5.2 mw. The cause of this reduction was not
determined.
The evaporation rate, tons steam per ton of waste was normal and
ranged from 2.16 to 2.66. The calculated heat value of the refuse 2115 to
2598 kcal/kg (8855 kJ/kg to 10,877 kJ/kg) [3807 to 4676 Btu/lb] also appears
to be typical of European waste.
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40
Boiler Water Treatment
The boiler water is treated by ion exchange using a system installed
by Theodor Christ AG of Basel and having the following specifications:
Cationic Resin:
Pressure
Maximum flow rate
Quantity treated with
each regeneration
Resin type
Resin quantity
Regenerating acid flow rate
Amount of 30% HC1 per
regeneration
Anionic Resin
Pressure
Maximum flow rate
Quantity treated with
each regeneration
3-6 atm
3 m3/hr
48 m
Amberlite IR 120
380 liters
2,5 m3/hr
95 kg 85 liters
3-6 atm
3 m3/hr
48 m3
Resin type
Regeneration caustic flow rate
Amount of 30% Na OH per
regeneration
Water Analysis
Specification
> 8.5
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Amberlite IR 410
3
2.7 in/hr
120 kg 90 liters
PH
Hydrazine
Phosphate
Silica (Si02)
2-5 mg/£
0.3
Measured on
9 May 1977
0.1
2.5
-------
41
Primary Air Supply
The primary air for each boiler is taken from the pit area by a
separate Bllttner-Schilde-Haas centrifugal-single-inlet blower rated at
30,000 Nm /h (17,655 cfm) at 280 mm (11 in) total pressure. The air is
delivered to 3 zones under the grate and the flow to each zone can be
controlled from the control room by means of butterfly valves where the
operator has an indication of zone air pressure and of valve position.
-------
42
Secondary Air
The secondary air is also taken from the pit area. Originally
the air jets were in both sidewalls, 3 horizontal groups of 6 jets each
located approximately one meter (3.28 ft) above the sloping grate. How-
ever, as discussed earlier in the section on Furnace Wall, the manufacturer
concluded that a principal cause of early failure of 9 tubes in the first
open boiler pass was the corrosive action of very hot reducing gases
adjacent to those tubes. Also, the sidewall jets appeared to encourage
accumulation of slag on the walls. In an effort to achieve better mixing
of air and gases the secondary air system was converted in 1974 to front-
wall and rear-wall jets, all 64 mm (2.5 in) dia jets. There are 15 jets
in the front refractory arch which enter the furnace at an angle of about
45 degrees directly above the first grate section. Figure 2-14 shows the
15 jets on the back wall. The blower supplying these rear jets has a capacity of
o
9000 Nm/h (5292 cfm) at a pressure of 400 mm (15.7 in) water. The jets in
the front of the furnace are supplied by a blower having a capacity of
6000 Nm/h (3528 cfm) at 500 mm (19.7 in) water. The flow rate to each
set of jets can be modulated from the control room by means of butterfly
valves. The revised jet arrangement has been so satisfactory that the
manufacturer expects to utilize only front and rear wall secondary air
jets in future designs.
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CO-FIRING EQUIPMENT
Figure 2-15 shows one of the 2 Elco air-atomizing oil burners
which are mounted at the side of each furnace toward the rear. (Fig-
ure 2-16 shows the effect of a similar sidewall burner at a hospital waste
incinerator in Cologne, W. Germany.) These burners are for the purpose
of firing waste oil when available. About 50 percent of the waste oil comes
from automotive service stations and 50 percent from industry. This in-
cludes some oil emulsions.
The waste oil is first received into a large heated concrete
settling tank where it is heated by a heating coil to 50 C (122 F)
and held for 3 days to allow solids to settle. From this tank it passes
through a fine mesh filter to a daily tank from which it is fired at
varying rates up to a maximum of 800 kg/hr (1761 Ib/hr) per boiler. The
filter must be cleaned every 2 or 3 months.
Plant practice is to reserve the waste oil for firing when the
refuse is wet or to dispose of the oil when all oil-storage space is filled.
Also, at mid-day when the highest revenue can be realized from the sale of
electricity the waste oil may be used. When firing oil both Burners on
opposite sides of each furnace are used. The burners require little main-
tenance but are inspected and cleaned every 2 months. They employ light
oil for a pilot flame. Some difficulty has been encountered with flotable
substances that accumulate at the top of the waste oil settling tank.
-------
FIGURE 2-15.
OIL BURNER ON SIDE OF AND TOWARD REAR OF FURNACE FOR
FIRING OF WASTE OIL (Courtesy of Widmer & Ernst)
-------
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Tertiary Air
Both furnaces are in process of being modified to incorporate side-
wall air cooling in the lower portion of the furnace. Figure 2-17 shows the
2 2
planned arrangement of 8.5 m (91 ft ) of air-cooled cast iron blocks to
be installed on both sidewalls above the grate. The total air supplied to
3
the blocks will be 6500 Nm /h (3825 cfm) at a pressure of 190 mm (7.5 in)
water. Figure 2-18 shows the air flow pattern which cools the blocks which
hang loosely on an air-cooled supporting framework. A Widmer & Ernst photograph
(Figure 2-19) shows a man applying the blocks to the sidewalls in an
European facility. Finally, Figure 2-20 shows the non-adhering results of
a similar furnace.
-------
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52
Energy Utilization Equipment
The energy from this plant is used in the form of electricity
used by the regional power system, process steam for the adjacent industrial
waste treatment plant, Fairtec, and hot water for plant heating and for
heating of the adjacent sewage treatment plant. The electricity is generated
in a 6500 KVA Brown-Boveri turbogenerator which consumes a maximum of 25 tonnes/h
(55,000 Ib/h) of steam at 40 atm (573 psig) and 400 C (725 F). Its effective
output is 5.2 mw. Its specific steam consumption is approximately 4.8 kg/kw-hr
(10.6 Ib/kw-hr). The condenser is cooled by river water. The condenser
is cleaned once every 3 months. Process steam is extracted at 1.5 bar (20 psig)
and 205 C (400 F). Heating water is supplied at 70 C to 90 C (160 to 198 F) .
All of the condensate is returned from the waste processing plant.
This summer it is planned to dismantle and reblade the turbine
to achieve increased power output from a higher rate of steam flow.
Figure 2-21 shows the scheme for heat and electricity distribution.
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53
THERMAL SYSTEM
ELECTRICAL SYSTEM
1. Boiler 5. Regulator 9. Feedwater heater
2. Turbine 6. Overflow condenser 10. Feedwater tank, deaerator
3. Generator 7. Condensate pump 11. Feedwater tank, pump
4. Condenser g. Air bleed 12. Heat exchanger
16kV I
n
1
t
6500kVA
6500KVA
AEW-Powerline
InternalPower
Supply
Fairtec
Industrial
Waste
Plant
Turbo- Sewage
Generator Treatment
Plant
FIGURE 2-21,
SCHEMATIC DIAGRAM OF THERMAL AND ELECTRICAL SYSTEMS
(Courtesy of Widmer & Ernst)
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54
POLLUTION CONTROL EQUIPMENT
There was no visible plume at any time during our 3-day visit
to this plant. Pollution control is by 2 single-field Elex electro-
static precipitators followed by 2 stage multicyclones. Without the
hopper the precipitators are 7 m high, 4.45 m wide, and 7 m deep. They
3
have a flow rate of 64,000 Nm /hr (37,664 scfm). Average velocity is
0.7 m/sec (2.3 ft/sec). The gas composition at the precipitator is
about:
• CO - 6-7 percent
o
Particulates are now limited to 100 mg/Nm corrected to 7% CO2. When
3 2
this plant was designed, the allowable limit was 150 mg/Nm . When
3
tested by the manufacturer in 1971, it achieved 111 mg/Nm . With
3
the multi-cyclone alone the emission was 1100 mg/Nm .
In Switzerland, waste-burning plants are limited to gaseous
emissions of:
• SO - 300 mg/Nm3
3
• HC1 - 500 mg/Nm
The precipitators and their duct configuration were tested
beforehand by Elex in small water model to assure a uniform flow pattern.
Residence time is 5.9 sec. Total plate area is 612 m2 (6587 ft2) with
2 3
a projected area of 952 m (10,247 ft.). The plates are cleaned inter-
mittently by a bottom rapper. The charging electrodes are cleaned by
a rapper at the top.
Output capacity is 55 KVA at 55,000 volts and 506 ma.
The fly ash hoppers are approximately 50 degree inverted
pyramids electrically heated and covered with 10 cm (4 in) of insula-
tion. The collected ash is removed continuously by star feeders which
discharge directly downward into the main residue quench tank.
The precipitator was guaranteed to achieve 97 percent effi-
ciency. Assuming an inlet loading of 5 grams/Nm^ the measured efficiency was
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55
97.8 percent. However, on 3 brief 40 minute tests on May 25, 1971,
3
the average inlet loading was only 1.846 g/Nm , the outlet was 0.111,
corresponding to an efficiency of 94.0 percent. The average CO
was 7.8 percent.
So far, the precipitator has needed no repairs. It is
cleaned once per year when the boiler is cleaned. For personnel pro-
tection, the access doors cannot be opened before an 8-multiple key
sequence is processed.
To achieve lower particulate emissions from future plants,
the manufacturer is considering the use of two-field precipitators.
The prcipitators have suffered no serious corrosion during
the normal weekend shutdowns. Initially cracks in the porcelain insula-
tors caused arcing but this was cleared up by replacing them with other
ceramic insulators. In 29,000 hrs of operation over 7 years there have
been no electrodes nor plates replaced.
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56
Wastewatejr Discharge
Boiler blowdown and cooling jacket water goes to the residue
quench tank from which any overflow goes to the adjacent sewage treatment
plant.
Federal regulations limit the temperature rise of river water
used for cooling to 6 C (10.8 F). Accordingly the turbo-condenser dis-
charge is diluted with clear effluent from the sewage plant giving an
effective temperature rise of one degree Celsius.
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57
Stack Construction
The 1.8m dia (5.9 ft) concrete stack is 80 m (262 ft) tall.
It was fabricated by Schilling of Dtlbendorf. Below the flue gas inlet the
chimney lining is acid-resistant refractory. Above it is normal refractory.
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58
Pollution Con trol_ Assessment
Since the plant was built the Federal emission limit for particulates
3
has been dropped from 150 mg to 100 mg/Nm at 7% CO,,, However, the stack
plume was never visible during our visit and with a busy railroad on one side
of the plant and the Limmat river on the other an effect of its emissions
would be minute.
All wastewater is treated by the adjacent sewage treatment plant.
The overall appearance of Swiss cities and countryside is very
clean. This low environmental pollution level is achieved by a minimum of
necessary regulation. New regulations are implemented with cautious deliberation,
On the other hand, old regulations are tightened where economically and tech-
nologically feasible. For example, in recent years, the particulate emission
3
limit to the atmosphere of 150 mg/Nm corrected to 7 percent C09 has been
dropped to 100. This new value is equivalent to 0.044 gr/scf. For 5,000 Btu/lb
refuse (LHV) (2778 kcal/kg) [ll,630 kj/kg] this amounts to about 0.11 lb/10 Btu
input (0.616 mg/106 kcal) [0.147 mg/kj].
A Swiss survey of municipal refuse shows that 50 percent of the
refuse averages about 6 kg HCl/tonne of waste and that 95 percent of the
refuse burned has less than 15 kg HCl/tonne. Potentially, this higher value
3
could result in about 1,700 mgHCl ,/Nm (0.0014 lb/1000 Ib) being discharged to
the atmosphere. Actually, an unknown amount will stay in the furnace, precip-
3
itator, and residue so probably less than 1,000 mg/Nrn (0.0008 lb/1000 Ib gas)
is emitted. The fact that scrubbers to remove HC1 from the hot gases have
not been well developed and little deleterious atmospheric concentrations of
HC1 have been observed leads the government to caution in regulation of this
emission. On the other hand, since HC1 emissions are obviously undesirable,
there has been a 3-4 year effort to encourage the substitution of innocuous
plastics for PVC in the Swiss economy. This still leaves the normal NaCl
and agricultural chlorine in refuse which constitutes about half of the total
amount of chlorine in refuse.
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59
If eventually scrubbers to remove HC1 become necessary, the regu-
latory staff is well aware of their disadvantages:
• Scrubber sludge
• Additional cost
• Corrosion
• Visible wet plume
• Acid wastewater
• Efficiency on fine particulates often low.
Hence, the Swiss concensus is not to require scrubbers unless HC1 removal is
proven highly necessary. Meanwhile, the PVC content of municipal refuse is being
monitored and each plant will be tested for HC1 emission about every 2 years.
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60
Noises
This plant, along with the Limmat River railroad track, highway, an<
hills is surrounded by industry and cultivated fields. It is remote from
human habitations and noise has been no problem. According to Swiss regula-
tions, no plant can emit at its boundary noise exceeding:
• 55 db (A) at night
• 65 db (A) in the day
• 80 db (A) peaks.
PERSONNEL AND MANAGEMENT
The plant is owned and operated by the Zweckverband Kehrichtver-
wertung Baden-Brugg. President of the organization, Dr. Zumbuhl, hires
the Plant Manager, who in turn, hires the remainder of the staff. The
governing board (Vorstand) and council meet about twice per year to make
major decisions.
This plant now operates 5 days per week with only 3 operators on
each of three shifts plus a standby operator, the Plant Manager, E. Luedi
and his assistant. The administrative and maintenance staff works 5 1/2
days (44 hrs) per week. One maintenance worker is full time and 3 others
are part time. When not working on maintenance these men can fill in
on other jobs. In January 1978 the plant will begin a 7-day week operation.
The total plant staff is now 18 and the manager indicated there should be
more. The manager is also responsible for the operation of the adjacent
sewage plant.
Total wages and salaries for 1976 were 825,163.65 Sw Fr ($332,541).
This is an average of $1535 per worker per month. Benefits in addition were
108,475.55 Sw Fr ($43,716) per year. An extensive annual report is prepared
with the assistance of local government accountants.
Each of the plant staff receives brief training except the scale
operator and custodian. No federal boiler operator's license is required.
This plant has a unique source of skilled personnel in that the world
headquarters of the Brown-Boveri Co. is located in Baden. Hence three of
the current shift foremen have had extensive prior experience in building
and assembling heavy power-generating machinery.
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61
New workers are first assigned to the assistant plant manager for
*
3 or 4 days per week to become familiar with the overall plant. Then they
are gradually transferred to work alongside the current operator on the job
to which they will be assigned. After 4 or 5 weeks they are expected to be
able to handle the task alone except for some assistance during start-up
and shut-down.
The Swiss Federation of Large Boiler Operators provides lectures
and training and also issues certificates for general boiler operation.
The Widmer + Ernst Co. has provided operation and maintenance instructions
on each plant component.
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62
Energy Marketing
The only energy export from this plant is as follows:
Electricity to:
1. Sewage treatment plant
2. Aargau Elektriztatswerk (AEW)
Steam to:
1. Fairtec, industrial waste processing plant
Hot water to:
1. Sewage treatment plant.
A long range plan has considered the possibilities for using turbine
exhaust steam for district heating in Baden, possibly tied in with waste
heat from a future nuclear plant.
The sewage plant receives electricity at the rate of 19,500 to
32,000 kw hr per week.
The electricity sold to the local network, AEW, derives a variable
revenue depending on time of day and depending on how much hydropower is
available to the network. In the winter hydropower is reduced because the
highland snowfall does not melt. In the summer, Switzerland as a whole,
has excess hydropower and exports electricity. The range of rates paid to
the Baden-Brugg plant is as follows; Sw Fr per kw hr (US cents/kw hr):
Winter Summer
High 0.045 (1.8) 0.030 (1.2)
Low 0.028 (1.1) 0.018 (0.7)
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63
ECONOMICS
Capital Investment
In 1970 this plant cost 16,400,000 Sw Fr. (the equivalent of
$6,560,000 U.S. in 1977$). This is $32,800 per tonne-day capacity. The
first cost included one million Swiss Francs for 2 electrostatic pre-
cipitators.
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64
Operating Costs
Table 2-4 is from the Statistical Statement in the 1976 Annual
Report showing the plant operation for the years 1975-1976 including operatinj
costs. For 1976, the net operating cost was 15.94 Sw Fr/tonne. Other costs
were added as follows:
Operation 15.94 Sw Fr/tonne $5.83/ton
Capital 22.60 8.27
Cash reserve 11.69 4.27
Average overall
Cost 50.23 18.37
Cost per person-
year 15.03 5.50
Total operating cost was made up as follows:
Operation and main-
tenance 1,408,566.70 Sw Fr $567,652.38
Interest and debt
reduction 942,370.30 379,775.23
Repairs 487,362.65 196,407.15
Total Annual Cost
1976 2,838,299.65 $1,143,834.76
However, for a population of 140,000 this total corresponds to $8.17 per
person instead of the $5.50 shown in Table 2-4.
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65
TABLE 2-4. PLANT INCOME FOR 1975 and 1976 (FROM STATISTICAL STATEMENT
IN 1976 ANNUAL REPORT)
Income from electricity
sold to AEW Fr. 514,041.80 422,716.—
Income per KWh Rp./kWh 3.89 3.42
Income per tonne waste Fr./t 13.02 10.89
Operating cost, principal (1)(2)(3) Fr./t 32.29 31.96
Operating cost, net (1)(2)(3) Fr./t 15.94 19.03
Capital cost Fr./t 22.60 23.22
Capital cost (1) % 40.08 40.88
Reserve Fr./t 11.69 8.88
Average cost per tonne Fr./t 50.23 51.13
Cost per inhabitant-year Fr./person-year 15.03 14.82
(1) without cash reserve
(2) without capital cost
(3) without electricity for sewage plant from AEW
* 1975: 5 day work week
1976: 5 1/2 day work week
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66
FINANCE
The total cost of the plant 16.5 x 10 SwFr ($6.65 x 106) was
financed by a regular bank loan of 10.4 x 10 SwFr plus joint financing
of the 6.1 x 10 SwFr remainder by Federal and Cantonal grants in the amount
£ f
of 2.5 x 10 SwFr from the Federal Government and 3.5 x 10 SwFr by the
canton of Aargau.
The interest on the debt ranges from 5.25 to 6 percent and the loan
is tax exempt. As of 1977, the original loan of 10.4 x 10 SwFr had been
reduced to 6.6 x 10 SwFr.
«U.S. GOVERNMENT PRINTING OFFICE: 1979 £20-007/6302 1-3
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