United States Office of Water and SW 176C.12
Environmental Protection Waste Management October 1979
Agency Washington, D.C. 20460
Solid Waste
&EPA European Refuse Fired
Energy Systems
Evaluation of Design Practices
Volume 12
-------
EPA
and State. So Lid Woi-te Mana.gme.nt
EUROPEAN REFUSE FIRED ENERGY SYSTEMS
EVALUATION OF DESIGN PRACTICES
Copenhagen: Amager
Denmark
tnip tiapoit (SW-776c.72) deAUtibeA wctfe
the. 0^-tce ofa Sotid WaAta undent c.ontna.c.t no. 6S-01-4376
and izpfioducad 04 ^ecex.ued fitLom the. dont^actofi.
The. ^ndingA AhouJLd be. at&u.bute.d to the. c.ontnjac.ton.
and not to the. fl^/cce ojj Bo Lid
Copies will be available from the
National Technical Information Service
U.S. Department of Commerce
Springfield, VA 22161
Volume 12
U.S. ENVIRONMENTAL PROTECTION AGENCY
1979
i ,- ', ,-
''(<-- -.,
-------
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.12) in the solid waste
management series.
U.S. Environmental Protection Agency
-------
TRIP REPORT
on
COPENHAGEN: AMAGER, DENMARK
on the contract
EVALUATION OF EUROPEAN REFUSE-FIRED
ENERGY SYSTEM DESIGN PRACTICES
in October 3-6, 1977
to
U.S. ENVIRONMENTAL PROTECTION AGENCY
EPA Contract No. 68-01-4376
RFP No. WA-76-B146
by
Philip R. Beltz and Richard B. Engdahl
March 31, 1978
BATTELLE
Columbus Laboratories
505 King Avenue
Columbus, Ohio 43201
-------
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.
-------
ii
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
LIST OF PERSONS CONTACTED, REFERENCED, OR CONSTRUCTION
PARTICIPANTS 1
Addresses 1
STATISTICAL SUMMARY 3
OVERALL SYSTEM SCHEMATIC 15
COMMUNITY DESCRIPTION 17
Geography 17
SOLID WASTE PRACTICES 20
Solid Waste Generation 20
Solid Waste Collection 22
Solid Waste Transfer 22
Provisions to Handle Bulky and Noncombustible Wastes 24
Solid Waste Disposal 24
DEVELOPMENT OF THE SYSTEM 28
Recommendations for System Development in North America 31
PLANT ARCHITECTURE AND AESTHETIC ACCEPTABILITY 33
TOTAL OPERATING SYSTEM 37
Maximum Rated Capacity 37
Forms of Operation 40
Operating Hours 41
Problems 43
Old Problems 43
Continuing Concerns 43
-------
TABLE OF CONTENTS
(Continued)
Page
REFUSE-FIRED HOT WATER GENERATOR EQUIPMENT . 44
Waste Input 44
Weighing Operation 46
Waste Storage and Retrieval 48
Furnace Hoppers, Feeders, and Swivel Gate 52
Primary (Underfire) Air 52
Secondary (Overfire) Air 56
Boiler Room Cool Air 56
Flue Gas Recirculation Hot Air 56
Flue Gas Fan 58
Fan Summary 58
Furnace Combustion Chamber 60
Burning Grate (Forward Pushing Step Grate) 60
Furnace Refactory Wall 69
Rotary Kiln 71
After Burning Chamber 75
Boiler (General) 76
Convection Section 79
Economizer 81
Boiler Water Treatment 81
Cofiring 81
ENERGY UTILIZATION EQUIPMENT 83
More of Mr. Blach's Comments on Heat Exploitation 85
-------
TABLE OF CONTENTS
(Continued)
Page
POLLUTION CONTROL EQUIPMENT 89
Air Pollution 89
Water Pollution 92
ASH HANDLING AND DISPOSAL 93
CHIMNEY 93
PERSONNEL AND MANAGEMENT 98
Personnel 98
Management 98
ECONOMICS 100
Capital Cost (Assets and Liabilities) 100
Annual Costs (Expenses and Revenues) 100
Profitableness at Exploitation of Heat 106
FINANCE HI
REFERENCES 112
LIST OF TABLES
TABLE 14-1. Population and Refuse Consumption in the Copenhagen
Immediate Metropolitan Area 21
Table 14-2. Primary, Secondary, Flue Gas and Recirculation
Fan Parameters 59
Table 14-3. Assets (March 31, 1976) at Copenhagen:Amager 101
Table 14-4. Liabilities (March 31, 1976) at Copenhagen:
Amager 102
Table 14-5. Annual Costs During 1975-1976 at Copenhagen:
Amager 103
Table 14-6. Revenues During 1975-1976 at Copenhagen:
Amager 104
-------
LIST OF TABLES
(Continued)
Table 14-7. Annual Costs and Revenues at Copenhagen:
Amager 105
Table 14-8. Operational Costs (Exclusive of Interest and
Depreciation) and Income by Heat Sale From
a Plant with Three Furnaces of 12 t/h for
Variable Net Calorific Values of Refuse and
Degree of Incineration Capacity 107
Table 14-9. Operational Costs (Exclusive of Interest and
Depreciation) and Income by Heat Sale From
a Plant with Two Furnaces of 3 t/h for
Variable Net Calorific Values of Refuse and
Degree of Incineration Capacity .108
LIST OF FIGURES
Figure 14-1. Engineering Drawing of Copenhagen:Amager 16
Figure 14-2. Map of Copenhagen, South and East Metropolitan
Area Served by the Amager Plant 18
Figure 14-3. Copenhagen:Amager Plant Located on Canal 19
Figure 14-4. Transfer Station Under Construction at Amager 23
Figure 14-5a. Ramp Leading to Transfer Station 25
Figure 14-5b. Bulky Waste Being Dropped into the Von Voll
Scissor Shear 25
Figure 14-5c. Trailer Load from the Transfer Station Being
Weighed Before Transport to the Uggelose
Landfill 25
Figure 14-6a. Landfill Operations at Uggelose, Denmark 27
Figure 14-6b. Landfill Operations at Uggelose, Denmark. . . 27
Figure 14-7. First Volund System Built at Gentofte in 1932 and
Decomissioned 40 Years Later in 1972 29
Figure 14-8. Volund's Procedure for System Development 32
Figure 14-9. Copenhagen:Amager Plant Located at Sea Level 34
-------
LIST OF FIGURES
(Continued)
Page
FIGURE 14-10a. Control Room at Copenhagen :Amager 36
Figure 14-10b. Lobby Entrance 36
Figure 14-10c. Cafeteria 36
Figure 14-10d. Conference Room 36
Figure 14-11. Maximum Rated Capacity on Volund Rotary
Kiln Furnaces 38
Figure 14-12. Total (Three Lines) Operation Hours per Month. ..... 42
Figure 14-13. Monthly Tonnage of Industrial1, Household, and
Total Refuse Weighed at the Copenhagen:
Amager Scales 45
Figure 14-14a. Scale House and Two Scales 47
Figure 14-14b. Plastic Card 47
Figure 14-14c. Monitor in Control Room of Truck Scale 47
Figure 14-14d. Digital Readout in Scale House 47
Figure 14-14e. Ramp to Tipping Floor 47
Figure 14-14f. Tipping Floor 47
Figure 14-14g. Tip Arrangement Permitting Good Crane View . 47
Figure 14-15a. Tipping Door that can Close 49
Figure 14-15b. Crane Operator Controlling Polyp Towards Hopper. ... 49
Figure 14-16a. Sven Polyp Grab at Copenhagen:Amager Going
Down for Another Load 51
Figure 14-16b. Schematic of Polyp 51
Figure 14-17. Sloping Air Intake Filters Above the Bunker at ,
Copenhagen:West Only (Raised Intakes at Amager). . . 54
Figure 14-18. Original and Raised Position of the Primary
Air Intake 55
-------
LIST OF FIGURES
(Continued)
Page
Figure 14-19. Six Dilution Sidewall Secondary Overfire Air
Jets at Copenhagen :Amager 57
Figure 14-20. General Design Configurations for Volund Furnaces. . . 61
Figure 14-21. Furnace Design (Two-Way Gas Grate and Rotary
Kiln) at the Old (1934) Frederiksberg Plant,
Dismantled in 1970 62
Figure 14-22. Volund's Lengthwise Placed Section of Grate 64
Figure 14-23. Volund's Movable Sections Hydraulically Driven
by a Transverse Driving Shaft Connected to
the Individual Sections by Pendulum Driving
Bars 65
Figure 14-24. One of the Earliest Volund Patents 66
Figure 14-25. Grate Furnace Exit Into a Rotary Kiln at One
of Volund's Plants 68
Figure 14-26. Rotary Kiln Being Repaired at Copenhagen:Amager. ... 73
Figure 14-27. Two Support Rings of a Volund Rotary Kiln 74
Figure 14-28. After Burning Chamber and Boiler at Copenhagen:
Amager 77
Figure 14-29. Amager Boiler Design 80
Figure 14-30. Copenhagen: Amager's Refuse Fired Energy Plant
in the Foreground and the Oil (or Coal?)
Fired Plant in the Background 84
Figure 14-31a. Insulated Hot Water Pipes Leaving Boiler 86
Figure 14-31b. Map of District Heating Network 86
Figure 14-31c. Pumps to Send Hot Water to the Power Plant
Which Sends the Hot Water to the District
Heating Network 86
Figure 14-32. Energy Delivery to the District Heating Network. ... 87
Figure 14-33a. Rubber Ash Conveyor at Copenhagen:Amager 94
-------
LIST OF FIGURES
(Continued)
Page
Figure 14-33b. Ferrous Separation From Ash at CopenhagenrAmager ... 94
Figure 14-34. Patent for Volund's Ash Sluice and Pusher 95
Figure 14-35. Ash Chute and Skip Hoist at Copenhagen:Amager 96
Figure 14-36. Management Structure of Copenhagen:Amager 99
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LIST OF PERSONS CONTACTED. REFERENCED. OR CONSTRUCTION PARTICIPANTS
Gabriel Silva Pinto
M. Rasmussen
Evald Blach
Jorgen Hildebrandt
Per Nilsson
Thomas Rosenberg
Architect
Consulting Building Engineers
Consulting Mechanical Engineers
Project Manager, Main Plant
Layout, Volund
Chief Engineer, Sales Activities
Volund
Former Chief Engineer, Volund
Plant Manager, Amager Plant
Chief of Development Department
Civil Engineer of the
Renholdnings Selskabet
Sales Manager, International
Incinerators, Inc., Atlanta,
Georgia,
J. Maglebye Architectural Office
Ramboll & Hannemann
Copenhagen Gas and Electricity
Services
Addresses
Refuse Fired Hot Water Generation Plant
Amager Forbraending
Kraftverksvej
2300 Copenhagen S
Denmark
Tele: (01) 950351
Vendor Headquarters
A/S Volund
11 Abildager
2600 Glostrup
Denmark
Tele: 02-452200
Telex: 33130 Volund Dk
Collection Organization
Renholdnings Selskabet
Since 1898
8-10-16 Kraftuaerksvej
2300 Copenhagen S
Amager Island
Denmark
Tele: 08233-5171
American Coordinating Firm
Mr. Gunnar Kjaer, President
Volund USA Ltd.
900 Jorie Boulevard
Oak Brook, Illinois 60521
Tele: (312) 655-1490
*This firm is owned by:
1. Volund A/S (Denmark)
2. Waste Management, Inc.
3. Jack Lyon & Assoc.
American Sales Representative
Mr. Ronald Heverin
Director of Marketing
Advanced Systems Group
Waste Management, Inc.
900 Jorie Boulevard
Oak Brook, Illinois 60521
Tele: (312) 654-8800
-------
WEKA-VERLAG Gmbh
8901 Kissing
Augsburgerstrasse 5
Germany
F.L. Smidth & Co.
11 West 12 Street
New York City, New York
Danish Boiler Association
Dansk kedel Forening
Sankt Pedersvej 8
2900 Hellerup
Denmark
Tele: (01)629211
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STATISTICAL SUMMARY
GENERAL
Name of plant Amager Plant
Location of plant Copenhagen, Denmark
Year completed 1970
Administration/Ownership Communities of interest consist of
several municipalities including
parts of Copenhagen
Area of plant approx. 3*1,000 m^
Area of building approx. 19,000 m^
Cost of construction, including approx. 115,000,000 D%Kr.
a building
Design Data
Plant capacity
Annually 220,000 - 330,000 tonnes/yr
Daily 864 tonnes/24 h
Capacity, each furnace
Daily 288 tonnes/24 h
Design hourly 12 tonnes/hour
Actual hourly 13 tonnes/hour
Number of furnace
Operating 3
Stand-by 0
Extension potential 3
Calorific value of refuse (design)
Lowest (design) 1,000 kcal/kg
Average (design) 2,000 kcal/kg
Highest (design) 2,500 kcal/kg
Calorific value of refuse (actual) 1,800 kcal/kg
-------
Composition of Refuse
Combustibles
Ash and inerts
Water
Furnace temperature
Minimum
Average
Maximum
Contents of unburnt matter in residue
Lowest
26$
42$
32$
Average
45$
26$
29$
Highest
55$
22$
23$
800 C
950 C
1,000 C
0-3$
OPERATION OF PLANT
Cost of operation and maintenance
Number of operators and workers
Number of officers
Operating hours of plant
Working hours of operators
Number of shifts
Electric power consumption
Water consumption
City water (excluding sea water) for
clinker cooling
Actual continuous operating time
Actual operating days
Maintenance and repair of plant
Regular or periodical overhaul and
repair including mechanic, electric,
and boiler systems
D.Kr. 35/tonne of refuse
45
10
24 hours/day 7 days/week
8 hours/day 5 days/week
5
1,000,000 KwH/month
7,000 tonnes/month
approx. 12 weeks
365 days/year
normal
REFUSE COLLECTION AND TRANSPORTATION
Population in refuse collection region
of the plant
Area of refuse collection of the plant
Amount of refuse collected, presently
Disposal of refuse
Incineration
550,000-600,000
138 km2
1,400-1,000 tonnes/day
50$
-------
Dumping at sea 0$
Reclamation 0%
Other:/dump/ industrial refuse 50$
Method of transportation Truck
Charge of collection Charged 30 D.Kr./t.
REFUSE STORING
Weighing equipment of refuse
Number 2
Type Automatic
Capacity 50 tonnes
Recording, printing, and summation Automatic
of weight
Refuse silo (bunker)
Number 1
Capacity 10,000 m3
Dimension
Length 48 m
Width 17 m
Depth 13 m
Specific weight of refuse 0.2-0.3 tonnes/m^
Storing capacity 3 days max. refuse delivery
Refuse silo door
Type Flap, double-hinged
Number 11
Dimension
Height 8.0 m
Width 3.8 m
Thickness, total 122 mm
Operation Hydraulic
Capacity 10,000 m3
Big refuse crusher None
REFUSE FIRING PLANT
Furnace
Filling hopper
-------
Number
Clear opening at top
Clear opening at bottom
Height
Thickness of plate
Materials
Volume
Filling chute
Number
Clear opening
Height
Thickness of plate
Volume
Swivel gate in filling chute (damper)
Number
Dimension
Thickness
Operation
Grate I
Width of grate
Length of grate
Area
Velocity of grate
Length of grate stroke
Type of grate
Materials of grate
Grate frame
Grate bar or plate
Side seal
Grate II
Width of grate
Length of grate
Area
Frequency of grate
Length of grate stroke
Type of grate
1 per furnace
6 m x 6 m
2.3 m x 1.15 m
6 m
8 mm
Mid steel
15 m3
1
2.3/2-7 m x 1.15 m
8.5 m
8 mm
19 m3
1
2.58 m x 1.26 m
10 mm
Manual
2.7 m
2.5 m
6.75 m2
3 stroke/min.
130 mm
Grate bar, grate plate
Meehanite HR
Meehanite HR
Nicromax
2.7 m
2.0 m
5.4 m2
3 stroke/min.
130 mm
Grate bar
-------
Materials of grate
Grate frame
Grate III
Width of grate
Length of grate
Area
Velocity of grate
Length of grate stroke
Type of grate
Materials of grate
Grate frame
Grate bar or plate
Side seal
Grate IV
Rotary kiln
Shape
Diameter
Inside of shell
Inside of lining
Length
Volume
Number of revolutions
Range
Normal
Inclination
Materials of shell
Materials of support ring
Materials of support roller
Materials of thrust roller
Number of support rings
Number of support rollers
Number of thrust rollers
Number of drive support rollers
Steps between grates
Number of steps
Height of steps between Grate I
Meehanite HR
2.7 m
5.0 m
13.5 m2
3 stroke/min.
130 mm
Grate bar, grate plate
Meehanite HR
Meehanite HR
Nicromax
None
Cylindrical
m
m
3.1
8 m
73 m
0-12 rph
6-8 rph
3 deg.
DIN 42.2 steel
High tensile strength steel castings
High tensile strength steel castings
High tensile strength steel castings
2
2
1
2
2
1.0 m
-------
and Grate II
Height of steps between Grate II
and Grate III
Steps beetween grate and rotary kiln
Number of steps
Height of step
Width of steps
Hopper under grate
Number
Thickness of plate
Size of chute
Clinker chute
Clear opening (or 100 ?)
Height
After combustion chamber
Volume
Hydraulic equipment for grate movement
and rotary kiln
Number per furnace
Hydraulic pump
Number per furnace
Capacity
Pressure
Motor
Oil tank
Hydraulic cylinder
Grate I
2.0 m
1
1.0 m
2.7 m
6 mm
240 x 240 mm
900 mm x 1 ,000 mm
1 ,900 mm
125 m3
1 set/furnace
Operating 2, standby 0
47 lit/min. each pump
70 kg/cm2g
15 HP each
600 liters
Grate II Grate III
Number
Cylinder bore
Cylinder stroke
Hydraulic motor for rotary kiln
Number per kiln
Revolution
Torque
Speed reduction equipment
Type
5
80 mm
130 mm
5
80 mm
130 mm
5
85 mm
130 mm
max. 1,200 rpm
3 kg-m
Double worm gear
-------
Number per kiln
Revolution
Torque
Ratio of reduction
max. 76 rph
1,272 kg-m
1:800
VENTILATING AND DRAFTING PLANT
Primary air (P.D. Fan)
Manufacturer
Number per furnace
Amount of air
Static pressure
Temperature
Number of revolutions
Drive type
Motor size
Secondary air fan (cooling air fan)
Number per furnace
Amount of air
Static pressure
Temperature
Number of revolutions
Drive type
Motor size
Flue gas fan (I.D. Fan)
Number per furnace
Amount of gas
Static pressure
Temperature
Number of revolutions
Drive type
Motor size
Recirculation fan
Number per furnace
Amount of air
Static pressure
Temperature
Nordisk Ventilator
1
45,000 Nm3/h
230 mmAq
30 C
1,490 rpm
Belt drive
75 HP
1
35,000 Nm3/h
460 mmAq
30 C
1,670 rpm
Belt drive
150 HP
1
107,000 Nm3/h
170 mmAq
350 C
1,010 rpm
Belt drive
220 HP
1
45,000 Nm3/h
220 mmAq
350 C
-------
10
Number of revolutions
Drive type
Motor size
Cooling air fan for by-pass damper
Steam air heater
1,1160 rpm
Belt drive
150 HP
None
None
CHIMNEY
Chimney
Type
Number
Diameter at top
Height
Gas velocity at top
Concrete with steel flue
1 per 4 furnace
2.8 m
150 m
max. 27 m/sec
AUXILIARY BURNING PLANT FOR FURNACE
Not necessary
DUST COLLECTING PLANT
Electrostatic precipitator
Number per furnace
Capacity
Gas temperature
Operating
Maximum
Dust content
Inlet
Outlet
Efficiency
Pressure drop
Multi-cyclone
107,000 Nm3/h
300 C
350 C
7.5 g/Nm3
0.15 g/Nm3
98*
5-10 mm water
None
-------
11
CLINKER AND FLY ASH TRANSPORTATION PLANT
Clinker transportation equipment under
clinker chute
Type Submerged conveyor stainless
steel laminated
Number per furnace 1
Capacity M tonnes/h
Speed 3 m/min
Width 1.1 m
Length of traveling 13 m
Ash transportation equipment under grates
and rotary kiln
Type Vibration conveyor
Number per furnace 1
Capacity 0.6 tonnes/h
Speed .6 - 1.2 m/min
Width diam. 300 mm
Length 1H.5 m
Ash transportation equipment under
boiler or gas cooler
Type Vibration conveyor (screw
conveyor submerged stainless
steel
Number per furnace 1
Capacity 0.6 tonnes/h
Speed .6 - 1.2 m/min
Width diam. 600 mm
Length 6.3 m
Fly ash transportation equipment under
Dust collector
Type Fluidizing
Number per furnace if
Capacity 0.6 tonnes/h
-------
12
Specific weight of clinker
Storing Capacity
Clinker transport
Number
Type
Length of traveling
Width
Speed
Disposal of clinker and fly ash
1.0 tonnes/m3
4 days
1 plus 1 stand-by
Laminated steel conveyor
50 m
1 m
3 m/min.
Landfill
Boiler
Method of gas cooling
Boiler
Type
Number per furnace
Design pressure
Working pressure
Hot water temperature
Feed water temperature
Capacity
Heating surface
Radiation heating surface
Convection heating surface
Superheater
Economizer (Normal steel tubes)
Economizer (Casted steel)
Gas air heater
Gas temperature
Inlet
Outlet
Waste heat boiler
Hot water boiler water tube
1
16 kg/cm2g
6 kg/cm^g
120 C
75 C
21.5 x 106 kcal/h
330 m2
330 m2
None
H55 m2
720 m2
None
800 C
280 - 320 C
-------
13
Clinker transport
Number
Type
Length of traveling
Width
Speed
Disposal of clinker and fly ash
\ plus 1 stand-by
Laminated steel conveyor
50 m
1 m
3 m/min.
Landfill
Boiler
Method of gas cooling
Boiler
Type
Number per furnace
Design pressure
Working pressure
Hot water temperature
Feed water temperature
Capacity
Heating surface
Radiation heating surface
Convection heating surface
Superheater
Economizer (Normal steel tubes)
Economizer (Casted steel)
Gas air heater
Gas temperature
Inlet
Outlet
Amount of gas
Lowest calorific value
Average calorific value
Highest calorific value
Boiler outlet gas temperature control
Heat utilization
Water spray gas cooler
Waste heat boiler
Hot water boiler water tube
1
16 kg/cm2g
6 kg/cm2g
120 C
75 C
21.5 x 106 kcal/h
330 m2
330 m2
None
1J55 m2
720 m2
None
800 C
280 - 320 C
33,000 Nm3/h
77*000 Nm3/h
98,500 Nm3/h
Yes, automatic
District heating
None
-------
14
Boiler cleaning equipment
Type Shot cleaning
Soot blower None
Hot water cooler
Type Air cooler
Number 2
Capacity 370 tonnes/h
Heat exchanged 18.3 x 106 kcal/h
Hot water temperature
Inlet 115 C
Outlet 60 C
Hot water pressure 10 kg/cm^g
-------
15
OVERALL SYSTEM SCHEMATIC
Figure 14-1 shows the cross-sectional schematic of the
Copenhagen: Amager plant designed and built by Volund A/S.
COMMUNITY DESCRIPTION
Geography
Figure 14-2 is a map of the Copenhagen metropolitan area.
Copenhagen itself is located on the east coast of Denmark, not far from
Sweden.
The Amager refuse-fired steam generator is shown at the north
end of Amager Island just southeast of downtown Copenhagen. Its twin unit
"Vest" or "West" described in Trip Report 15.
The terrain is rather flat, which is typical of eastern Denmark.
The Amager plant (see Figure 14-3) is located right on the canal
separating Amager Island from the main Danish island to Amager's north.
Amager Island was originally unimproved swamp land that has been
"poldered" with pilings, dykes, and debris fill over many centuries. Being
at sea level did interfere with construction in two ways. First, numerous
pilings had to be sunk. Secondly, the refuse bunker pit had to be shallow
and encased in special water protective coatings.
The population in the City of Copenhagen proper has fallen from
550,000, 10 years ago, to 430,000 presently. Reasons are typical of those
in many large cities. Basically young families are moving to the suburbs,
leaving the city for students, government workers, retired people, and
those wishing a short commute to work. The Amager plant serves about
620,000 people in central, east, and southern Copenhagen and those
residents of the Amager Island.
-------
16
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Plant
West Refuse Plant
FIGURE 14-2. MAP OF COPENHAGEN, SOUTH AND EAST METROPOLITAN AREA
SERVED BY THE AMAGER PLANT
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18
FIGURE 14-3. COPENHAGEN:AMAGER PLANT LOCATED ON CANAL
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19
SOLID WASTE PRACTICES
Solid Waste Generation
The "immediate" Copenhagen metropolitan area, as served by the
two large Volund plants (Amager and West), has a total population of
1,137,978 and generates 509,246 tonnes (560,171 tons) per year as shown in
Table 14-1.
Five communities sent 253,439 tonnes (278,783 tons) to
Copenhagen: Amager during the 1975/1976 fiscal year. On a 7-day burning
basis, about 694 tonnes (763 tons) per day were consumed. These figures
compare with the rated capacity of 864 tonnes (950 tons).
Collections are higher than the national average from offices,
stores, etc. However, household waste collections are lower than normal.
Bulky and garden waste is collected separately and usually landfilled.
Only 9 percent of Copenhagen's residents have gardens. Vegetative waste
amounts to 10 percent of the total household waste as an annual average.
Household generation rate figures were provided as follows:
City of Copenhagen 0.8 to 1.0 kg/person/day
Suburbs 1.2 to 1.5 kg/person/day
Metropolitan Area 1.0 to 1.4 kg/person/day
In 1975-1976, households in the Amager district generated 351 kg
per person. Adding commercial and industrial refuse brings the total to
466 kg per person. This translates to a combustible receivable rate of
1.226 Kg (2.7 pounds per day)/person day.
The refuse composition has been changing over the years to about
these figures:
1964/1965 1970
Heat Value (kcal/kg) 1,600 1,800-2,000
Moisture (percent) 35 33
Combustibles (percent) 40 45
Noncombustibles (percent) 25 22 23
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20
TABLE 14-1. POPULATION AND REFUSE CONSUMPTION IN THE IMMEDIATE
COPENHAGEN METROPOLITAN AREA
Population (Inhabitants)
I/S Amager Area
I/S Vest* Area
TOTAL
Refuse Consumption (Tonnes)
I/S Amager Plant
I/S Vest Plant
TOTAL
April 1, 1974
524,955
581,333
1,106,288
1974-1975
224,449
215,224
439,673
April 1, 1975
580,556
575,996
1,156,552
1975-1976
255,488
234,230
489,718
April 1, 1976
568,343
569,635
1,137,978
1976-1977
255,807
253,439
509,246
* Vest is translated to West.
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21
Solid Waste Collection
Delivery is by local garbage trucks. Therefore, there is
little, if any, bulky waste burned.
The overall cost for collection and disposal averages about 465
D.Kr. ($95) per year per person throughout Denmark.
Waste has been collected since 1898 by a not-for-profit society,
Renholdnings Selskabet. Much could be written regarding this very
successfful organization. One item of interest is that each walking
collector has a computer printout that tells him exactly how many Danish
Kroner he will earn by "traveling 17 horizontal steps, three vertical
steps, picking up a 10 liter can ...".
Comment: We are unaware of any collection system as detailed and
filled with motivational factors as the system at Renholdnings.
Further information is available.
Solid Waste Transfer
The transfer activity at Amager is unlike that of West. A large
transfer station is shown under construction in 1974 in Figure 14-4. The
area's industrial waste and household bulky waste is taken to this
transfer station located on the grounds of the Amager plant. Some of the
waste is then transferred to the Uggelose landfill located 37 km (23 mi)
northwest of Amager and inland. During 1975-1976, 32,374 garbage trucks
entered the transfer station. Some combustible waste was taken to the
refuse burning plant. About 13,723 transfer trailer loads were taken to
the Uggelose landfill.
Hazardous waste collected at the Amager plant is later
transported to the Federal hazardous waste treatment center at
Nyborg, Denmark.
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22
FIGURE 14-4.
TRANSFER STATION UNDER CONSTRUCTION AT AMAGER.
PHOTO TAKEN FROM WINDOW AT THE AMAGER REFUSE
BURNING PLANT. THE STORAGE YARD OF THE
RENHOLDNINGS SELSKABET COLLECTION ORGANIZATION
IS SHOWN IN BETWEEN.
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23
Provisions to Handle Bulky and Noncombustible Wastes
Homeowners must call the city of residence if they wish their
bulky waste picked up.
The self-contained Amager plant itself has no provision to
handle bulky wastes. As previously stated, adjoining the plant is the
transfer station. Trucks with bulky or noncombustible loads are weighed at
the same scale as is household refuse. Referring back to the aireal photo
in Figure 14-3, the trucks behind of the chimney, up and around to the
left out of the picture, and to the transfer station.
Figure l4-5a shows the ramp leading to the completed station. An
operator is about to dump a load of bulky material into a Von Roll scissor
shear in Figure 14-Sb. Size reduced combustible material is then hauled
directly to the refuse burning plant. If most of the material is
noncombustible, it is compacted, weighed (see Figure l4-5c), and sent to
the Ugglose landfill (30 km (19 mi) northwest of Amager.
The Von Roll shear can process up to 80 m3/hour (105 yd3/hour).
It operates intermittently and has a hydraulic drive. One man operates
the crane and shear on the day shift. The maintenance record has been
very good.
Solid Waste Disposal
The greater* Copenhagen metropolitan area is now served by eight
refuse-fired energy plants. All of the following are within a 32 km (20
mi) semicircle radius of Copenhagen:
Vest (West)
Amager
Brondby
Taastrup
Roskilde
Albertslund
Horsholm
Helsinor
*"Greater" metropolitan area with 8 plants is differentiated from the
"Immediate" Copenhagen metropolitan area having only the Amager and West plants.
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24
FIGURE 14-5a. RAMP LEADING TO TRANSFER STATION
FIGURE 14-5b. BULKY WASTE BEING DROPPED
INTO THE VON ROLL
SCISSOR SHEAR
FIGURE 14-5c.
TRAILER LOAD FROM THE TRANSFER STATION BEING WEIGHED BEFORE
TRANSPORT TO THE UGGELOSE LANDFILL
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25
Figures 1^-6a and l4-6b show landfill operations at the Uggelose
site northwest of Copenhagen.
In previous years, composting was practiced at two sites west of
Copenhagen. Eventually, there was some talk about mercury and cadmium
content. Perhaps too, the market for compost material was not great. For
whatever reasons, it was closed. Now, however, as is often the case,
composting is returning at a new site northwest of Copenhagen beginning in
January, 1978.
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26
FIGURE 14-6a. LANDFILL OPERATIONS AT UGGELOSE, DENMARK
FIGURE 14-6b. LANDFILL OPERATIONS AT UGGELOSE, DENMARK:
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27
DEVELOPMENT OF THE SYSTEM
Waste-to-energy began in Copenhagen in the early 1930's with the
1932 commissioning of the two 144-tonne (158 ton) per day Volund
grate/rotary kiln furnaces at Gentofte, each with a three-drum boiler as
shown in Figure 14-7. The steam was used to make electricity as specified
by the city's Electrical Board. This construction was followed by two
similar Volund units at Frederiksberg in 1934.
These two plants served Copenhagen well for 40 years. During
that time, these plants had reached their capacity. Therefore excess
refuse had to be landfilled both inland and on the sea coast. Referring
back to the map, Figure 14-2, notice the large undeveloped area in the
western part of Amager Island. This was basically low swamp land that has
been filled in with both demolition debris and household refuse.
During the 1960's, when knowledge of landfill leachate damages
became better known and when neighbors became upset over blowing trash,
etc., local citizens groups on Amager Island were effective in getting the
attention of elected officials.
For a time, it seemed that each community wanted to
independently solve its solid waste disposal problems. Finally, one of the
island communities decided to build a resource recovery plant. Others soon
followed. Eventually the City of Copenhagen joined in the development.
Incidentally, the excitement about Amager encouraged the
residents west of Copenhagen to develop a similar system now called "Vest"
or"West". Eventually, the Copenhagen Gas and Electric Company conducted a
study that resulted in the recommendation that two new refuse-fired hot
water generators be built to replace Gentofte and Frederiksberg.
Of note was that the competitive approach provided both
organizations with a quantity discount if both purchased similar units.
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28
FIGURE 14-7. FIRST VOLUND SYSTEM BUILT AT GENTOFTE IN 1932 AND
DECOMISSIONED 40 YEARS LATER IN 1972
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29
The competitors at Amager were:
Heenan-Froud
Martin
VKW
Volund
Von Roll
Officials remember that VKW, Volund, and Von Roll had the lowest
single unit prices (i.e., nonquantity discount). Other excellent Volund
plants in Denmark, the long history (40 years) of successful operations at
f
Gentofte and Frederiksberg, the low (maybe not the lowest) single plant
price, the quantity discount, and the Volund headquarters being nearby all
contributed to the decision favoring Volund.
Construction began in 1965 with 2 year's of sea and earth
reclamation. Plant construction began in 1967 and was completed in 1970.
Construction at Amager preceded work at West. Both began operation within
2 months of each other.
Improvements were made to both plants above what was technically
specified in the contract. Unfortunately the Amager building was not fit
to accept the improved ash transport system as was done at West. The
refuse input cranes and the ash discharge equipment are just two examples
that are discussed later in this report.
Copenhagen:Amager is owned by the five communities it serves, as
are listed in the "Organization" section at the end of this trip report.
Amager started operations in February 28, 1974 with three furnaces,
each designed to burn 12 tonne (13.2 ton) per hour assuming 2,500 kcal/kg.
Comment: Many of the more precise interviewees refer to "xx
tonnes per hour assuming y,yyy kcal/kg". After all, the
limiting factor is not how much refuse weight can mechanically
be pushed through the unit. Rather, the limiting factor is the
heat release rate that will not unduly affect system reliability.
Figure 14-8 shows the development of a Volund system.
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30
Volund's Relation to the North American Market
Volund A/G initiated activity in North America Janauary 9, 19^8
with the F. L. Smidth & Co. Smidth had the "sole and exclusive rights to
make, sell and/or use the VOLUND INCINERATOR SYSTEM ...in the United
States...Canada and Mexico".
Also in 19^8, Smidth and The Hardaway Construction Company of
Columbus, Georgia formed a joint venture company called International
Incinerators Incorporated (III) with offices in Atlanta, Georgia. Ill
was to "devote its best efforts to an aggressive attempt to obtain orders
from purchasers ... (in North America)... for the sale or installation of
apparatus and equipment made in accordance with the VOLUND INCINERATOR
SYSTEM".
With this charter , III sold 13 municipal waste incinerators, 2
of which had energy recovery. They also sold 3 industrial waste
incinerators. During this time of cooperation, III utilized many of the
Volund A/G patents and site-specific drawings. In addition, III developed
many of their own techniques and filed patents. Eventually many of the
early Volund A/G patents expired. Yet Volund A/G continued to file
patents in America.
With the Congress passing the Clean Air Act of 1970 and the
ensuing regulations on incinerators, many units closed. Few new orders
(regardless of manufacturer) were placed after 1970. In fact III had some
of the very last orders. Nevertheless the future looked bleak. Ill
survived on their replacement parts business.
Eventually the license agreement between F. L. Smidth (the 50
percent owner of III) ceased effective December 31, 1975. Smidth then
sold its shares to the other original joint partner The Hardaway
Construction Company.
Subsequently Volund A/G and III (now 100 percent owned by
Hardaway) were not able to come to agreement on a new license.
Volund A/G continued efforts to find a new licensee. Finally a
joint venture corporation was founded and is known as Volund USA (VUSA).
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31
An abreviated name used orally is VUSA. It is owned jointly by
the" following parties:
Volund A/G (Glostrup, Denmark)
Waste Management, Inc. (Oak Brook, Illinois)
Jack Lyon & Assoc. (Washington, D.C.)
Others
30 percent
30 percent,
30 percent
10 percent
We have been informed that VUSA would like potential purchases
of VOLUND INCINERATOR SYSTEMS to contact:
Sales, Construction, Operations
Mr. Ronald Heverin
Director of Marketing
Advanced Systems Group
Waste Management, Inc.
900 Jorie Boulevard
Oak Brook, Illinois 60521
Engineering, Design, Start-up
Mr. Gunnar Kjaer
President
Volund USA
900 Jorie Boulevard
Oak Brook, Illinois 60521
Frankly, both Volund A/G and III lay claim and probably desire
recognition for these 13 or so American plants. All plants are shown in
the current inventory published separately by Volund A/G and III.
Effectively, this means that a community desiring "something
that looks like a Volund grate followed by a rotary kiln" has two
potential vendors. Some would speculate that this is an unnatural
situation that still has not settled.
Volund has prepared a block flow diagram showing how they view
the developmental process for these systems (see Figure 1U-8).
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32
Waste Problem
Wa-tc \mount Preliminary w
waste /vmouni Investigation wa^ic
Types
1
_ .^ .
1
nment
Building Prclimimrv Prnicct Mechanical
and Plant Techniques Preliminary I reject Engineering
2
Economv Approval Enviro
tconomy of Authorities tnviro
Offer
nment
Plint Turhnimip . HptTilnrl Prniprt Mechanical
Plant lecnmque Detailed Project - Englneering
., , ^ . . ^ . , ,
El-erection
3 4
iction
Erection
^ ^
>eration
Test Running
Preliminary Investigation I 3 I Turnkey Job
2 I Preliminary Project
4 I Machinery Delivery
FIGURE 14-8. VOLUND'S PROCEDURE FOR SYSTEM DEVELOPMENT
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33
PLANT ARCHITECTURE AND AESTHETIC ACCEPTABILITY
Plant architecture at both the Amager and West plants is
excellent to outstanding. Yet there are important differences between the
two plants caused (1) by the site location, and (2) partly by the type of
construction contract.
The Amager site is located on "new" land that is an extension of
Amager Island (see Figure 14-9). Being right on the sea, the refuse pit is
shallow and limited to only 4 m (13 ft) below sea level.
The Amager plant is situated on a land parcel of 31,500 m2 (7
acres) leased from the City of Copenhagen. The building itself is on
8,400 m2 (1.87 acres). The floor space within the plant totals 25,37*1 m2
(5.64 acres). Finally, the cubic content of the building is 244,805 m3
(8.6 million ft3).
It is truly in a "nonresidential" industrial area and was thus
designed with a functional rectangular industrial theme. West, by
contrast, is in a residential neighborhood and has interesting modular
building block and exterior wall themes. The landscaping effect (and cost)
was much more at West.
Of note is that since 1970, the Copenhagen Town Hall has not
received a single complaint from the citizens about Amager waste disposal.
Perhaps another reason for Amager's modest but attractive
appearance is that vendor competition for construction of Amager was under
a traditional "fixed price" contract where most items were agreed to ahead
of time. West, however, was built under a "cost plus fixed fee"
arrangement. Thus, at West, there was an increased tendency to opt for the
"best" but not necessarily for the "most economical".
Despite the identical refuse input requirements and similar
processing equipment, there was more attention to aesthetics at the West
plant. As such, West was 25,000,000 D.Kr. ($4,800,000) more expensive.
The building height is 25 m (83 ft). The stack is very tall at
150 m (492 ft).
At both plants, everything that could produce noise is enclosed.
The tipping floor for refuse collection trucks is fully enclosed. The
electrostatic precipitator, often on plant roofs, is enclosed.
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FIGURE 14-9. COPENHAGEN:AMAGER PLANT LOCATED
AT SEA LEVEL
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35
The administration portion of the building is indistinguishable
as part of the total monolithic structure. The only clue to its position
is the semicircle parking lot clearly seen in the previous Figure 1*1-3
Figures 1^1-IOa, b, c, and d show four very clean rooms where
Amager staff work. The rooms are attractive, well lighted, functional, and
generally pleasant. Comments were made several times during Battelle's
visits in Scandanavia that such pleasant surroundings are necessary to
attract and keep the desired kind of employees.
A publication, Amager-forbraending Interersentskab^ ^), has
several paragraphs of interest regarding architecture.
"The building is constructed of reinforced concrete, with an
exterior cladding of concrete components. The entire north wall
has been designed so that it can be moved if the plant is
extended and has, therefore, been built as a light steel
construction with aluminum cladding. The top of the silo is
likewise covered with aluminum. The size of the lot permits an
extension with an additional three furnaces to a total of six
furnaces, and the technical assistance rooms, pump rooms, etc.,
as well as administration offices and personnel rooms have been
given the proper dimensions for this purpose."
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36
FIGURE 14-10a. CONTROL ROOM AT COPENHAGENrAMAGER
FIGURE 14-10b, LOBBY
ENTRANCE
FIGURE 14-10c. CAFETERIA
FIGURE 14-10d. CONFERENCE
ROOM
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37
TOTAL OPERATING SYSTEM
Maximum Rated Capacity
Battelle's host for the Volund visit was Gabriel Silva Pinto. In
April, 1976, he wrote an excellent article in an internal Volund
publication* that discusses basic design of the total operating system.
The following summarizes the article and Figure 14-11.
For purposes of the vendor's guarantee to the customer, there
must be a clear understanding of the relation between Maximum Rated
Capacity (MRC) and Lower Heating Value (LHV). The numbers used in the
example figure are those associated with the Volund Rotary Kiln Furnaces.
For each furnace designed by Volund, a theoretical diagram,
similar to Figure 14-11, is developed. Its purpose is to show how the MRC
(tonnes/hr) is a function of the refuse's LHV (kcal/kg).
As an example, assume that the LHV is 2,000 kcal/kg.*»
Typically, such municipal solid waste has the following composition:
Percent
Inerts 25.0
Moisture 30.0
Combustibles
Carbon 8.6
Cellulose 34.8
Plastics 1.6
Total Combustibles 45.5
TOTAL 100.0
* See Reference 4.
** Amager was designed with expected average LHV of 2,000 kcal/kg.
However, the actual is closer to 1,800 kcal/kg.
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38
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39
The refuse feeder is to be adjusted so that the refuse layer on
the grate is 1 m (3.3 ft). This type of refuse has an average density of 200
kg/m3 ( 336 pounds/yd3).
More must be known about the specific system before the MRC
answer (in tonnes/hr) can be given. The effective grate area must be
known. The following formula relates key variables:
/tonnes^ Effective Grate Area (m2) . Grate Load /kcal \
\^ hour / = \_m2. hour /
Lower Heating Value /kcal\ . 1000 /kg \
^ kg / (^tonne /
At this point, some rules of thumb need to be applied:
For hotter refuse with LHV of 1,800 to 2,500 kcal/kg, the
grate load ranges from 600,000 to 650,000 kcal/m2 . hr.
For cooler refuse with LHV under 1,800 kcal/kg, the grate
load ranges from 450,000 to 550,000 kcal/m2 . hr.
Experience of Volund must be used to actually estimate the grate load. But
once estimated, the capacity can be determined. Mr. Pinto's example does
not refer to any one system. Therefore, we have arbitrarily added capacity
figures of 10 to 14 tonnes per hour.
An important design consideration can be seen from the capacity
versus LHV curve. It is uni-modal peaking at 1,200-1,400 kcal/kg. As an
example, it is assumed that the plant is nominally designed to burn 12
tonnes per hour of refuse assuming it to have a 2,000 LHV.
Perhaps on a spring day, rain is excessive. The moisture
percent rises from its normal 30 percent to 37 percent; the combustibles
fall from 45 percent to 38 percent; the density increases from 200 kg/m3
to 300 kg/m3; and the inerts remain constant. The air preheater remains
unchanged and the use of any other fuel remains unchanged.
With the conditions of the wet waste given, the operator may
increase the feed rate, raise the feed layer thickness to 120 cm (3-9 ft),
and thus increase the throughput from its nominal 12 tonnes/hour up to 13
tonnes/hour.
This, of course, has a logical limit. If the refuse becomes too
wet, full of inerts, and lacking in LHV, then less tonnes per hour can be
processed. The furnace could easily choke on even 8 tonnes/hour of soggy
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40
rags and house furnace ashes if autothermic reactions are not possible.
In the other direction, above a LHV of 2,000, this particular
furnace should process slightly less refuse per hour.
Mr. E. Blach, Volund's former chief engineer, wrote in 1969 an
excellent paper outlining Volund's product offerings and its philosophy.
The following section presents some of the philosophy of how plants should
be operated. Several of his other sections appear later.
Forms of Operation
"The best way of running an incinerator plant is running it
24 hours a day, i.e., continuous operation. The big variations
of temperature wear in a furnace and the auxiliary machinery
than a steady operation, and corrosion and cleaning problems,
etc. in the boiler part also decrease by continual operation.
With regard to possibilities of maintenance and repair,
continual operation is not possible for a one-furnace plant, and
that is one of the reasons why an incinerator plant should
usually consist of at least two-furnace units. Unfortunately,
this is often not economically possible at the small plants.
An ideal way of operation for plants with several furnaces
is obtained by always keeping a spare oven, while the other or
the others run continuously. Through a convenient rotation so
that the furnaces alternately are taken out of operation, there
is plenty of time for inspection, maintenance, and repair of
each furnace. Small damages can thus be found and repaired
before they spread and require big and expensive repairs. At
one-furnace plants, the possibilities of inspection are smaller
and it can be tempting to let a long time pass between
maintenance and repair stops so that the damages grow big and
expensive to repair.
With noncontinuous operation, which in practice is a one- or
two- shift operation, the furnace is stopped. When the operation
is to be discontinued for 6 to 8 hours the furnace is fed with
suitable amount of refuse proportionally to the standstill
period. When the furnace is approximately full with refuse the
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grate movement and combustion air as well as I.D. fan are
stopped. The natural draught will then keep a slow combustion,
which develop sufficient heat to keep the plant warm all through
so that it can quickly get up to full capacity, when it is
started again. After a couple of hours, the temperature of the
flue gases will be so low, that there is the risk of
condensation, and thus corrosion in the convection part of the
boiler. However, the boiler water still can be kept at full
temperature, and the boiler chute can ensure minimum 70 C return
flow temperature.
However, at stops of more than 6 to 8 hours, there must be
taken special measures, such as by-pass with damper around the
boiler and its convection part. This is a rather difficult
construction to carry out in sufficiently strong and practical
form because of the high temperatures.
Furthermore, it results in the operational inconveniencce
that changing over cannot take place till the flue gas
temperature is below 400 C, which normally means after 3 to 4
hours' stop. During weekend stoppages, the temperature of the
boiler water cannot be maintained, and it will in this case be
necessary also to keep the boiler warm by circulation of hot
water." perhaps by a standby boiler.
Operating Hours
The monthly operating hours for the three-line total are shown
in Figure 14-12. At the recent average of 1,700 hours per month, the
plant lines operated about 80 percent of the time.
During the 1975-1976 fiscal year (April 1 to March 31, the three
furnaces together operated 19,663 hours or 75 percent of time available.
This equates to an average of 13 tonnes (14.3 tons) per hour per furnace.
This compares with a design capacity of 12 tonnes (13.2 tons) per hour per
furnace. This higher refuse flow rate is consistent with the previous
discussion on maximum rated capacity. Because the average calorific value
is 1,800 kcal/kg, more refuse can be processed.
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42
1000 1100
1972
1973
APRIL
MAJ
JUNI
JULI
AUGUST
SEPTEMBER
OKTOBER
NOVEMBER
DECEMBER
JANUAR
FEBRUAR
MARTS
1973
APRIL
1974 JUN"!
JULI
AUGUST
SEPTEMBER
OKTOBER
NOVEMBER
DECEMBER
JANUAR
FEBRUAR
MARTS
APRIL
MAJ
1974
1975
JULI
AUGUST
SEPTEMBER
OKTOBER
NOVEMBER
DECEMBER
JANUAR
FEBRUAR
MARTS
1976 JUNI
JULI
AUGUST
SEPTEMBER
OKTOBER
NOVEMBER
DECEMBER
JANUAR
FEBRUAR
MARTS
1200
Hours
1300 1400 1500
1600
1700
1800
1900
2000
2100 2200
X
H
53
g
W
53
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43
Problems
Plant officials and Volund representatives have identified three
old and partially solved problems as well as five continuing concerns.
These are listed here and discussed later in the report.
Old Problems
The crane was under capacity
The grate-furnace refractory grossly failed due to poor
anchoring
The ash handling conveyor system had excessive wear due to
fines buildup
Continuing Concerns
The rotary kiln lining must occasionally be repaired
The convection section has dew point corrosion due to the
low temperature boiler feedwater
The economizer must be manually cleaned every 1,500 to 2,000
hours, thus, setting the maintenance schedule
The electrostatic precipitator corrodes slightly due to
running "hot" when the economizer is clogged and is not
properly cooling the flue gases
The ash handling system, while improved, is still causing
problems due to "fines".
REFUSE-FIRED HOT WATER GENERATOR EQUIPMENT
Waste Input
The plant receives normal household, commercial, hospital, and
light industrial refuse (see Figure 14-13). Because of the chute size, the
maximum refuse object size is 1 m (3 ft). Aaager, in contrast to West, has
no shredder. Instead, a transfer station adjoins the Amager plant.
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44
Tonnes/Month
TON 2000 4000 6000
8000
1972
APRIL
Ib/O JUNI
JULI
AUGUST
SEPTEMBER
OKTOBER
NOVEMBER
DECEMBER
JANUAR
FEBRUAR
MARTS
APRIL
MAJ
1973
1974
JULI
AUGUST
SEPTEMBER
OKTOBER
NOVEMBER
DECEMBER
JANUAR
FEBRUAR
MARTS
1974
1975
APRIL
MAJ
JULI
AUGUST
SEPTEMBER
OKTOBER
NOVEMBER
DECEMBER
JANUAR
FEBRUAR
MARTS
1975
1976
APRIL
MAJ
JULI
AUGUST
SEPTEMBER
OKTOBER
NOVEMBER
DECEMBER
JANUAR
FE'BRUAR
MARTS
10000 12000 14000 16000 18000 20000 22000 24000 26000
w
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45
Because of the extensive vegetable farming on Amager Island, the
plant receives much garden waste in the spring and summer.
The sewage sludge could be dischharged directly into the pit or
in a special built silo with the necessary transport arrangement all of it
in air tight execution. The waste oil would be stored in tanks and pumped
to special burners.
At the moment the only sludge type burned in West and Auger are
ridlings form the course grid at the water treatment plants. This matter
which comes in containers is infiltrated and if it had to be treated in
other way shedding would be necessary. On the Volund rotary kiln plant
direct feeding is possible. While these containers come every day to the
plants the amounts can not be measured in percentages of the total waste.
The plants at West and Amager were designed to burn waste oil,
but a parallel development on the complete treatment of all hazardous
chemical- and industrial wastes gave the best solution for the problem as
the waste oil today is purified and resold at Nyborg. Thus the
installations have never used the waste oil burning facilities.
The plant was designed for lower heating value waste between
1,000 and 2,500 kcal/kg (1,800 and 4,500 Btu/pound) . The average is
actually 1,800 kcal/kg (3,240 Btu/pound) which is lower than at West.
About 400 vehicles per day deliver waste to the pit. Ownership
of the vehicles falls into three categories: private, public, and
not-for-profit utility collection. In this third category, Renholdnings
Selskabet (Cleaning Holding Company) was established back in 1898. This is
the most noteworthy collection operation observed throughout the European
visit. The company was formed in response to the series of epidemics or
plagues in the latter part of the 19th century.
Weighing Operation
Arriving trucks proceed to one of the two load cells, 50 tonne
(55 ton) scales manufactured by Philips of Holland (see Figure l4-l4a).
Drivers produce their universal plastic cards (Figure l4-l4b) that
identify the vehicle owner, etc. This information, along with the gross
weight, is fed into the computer, where the tare weight, mailing address,
etc. are stored.
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46
FIGURE 14-14a. SCALE
HOUSE AND TWO SCALES
FIGURE 14-14c. MONITOR
IN CONTROL ROOM OF
TRUCK SCALE
FIGURE 14-14b. PLASTIC CARD
FIGURE 14-14d. DIGITAL READOUT IN SCALE HOUSE
FIGURE 14-14e. RAMP TO
TIPPING FLOOR
FIGURE 14-14f.
FLOOR
TIPPING
FIGURE 14-14g. TIP
ARRANGEMENT PERMITTING
GOOD CRANE VIEW
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47
Occasionally the plastic cards jam, break, or become lost. In
this event, the driver would have to get out of the truck and spend
several minutes in the scale house filling out a form. The cards were
replaced on an as-needed basis. They have changed the system so that every
6 months all of the plastic cards are changed at once.
At the time of the visit in October, 1977, a particular card
would work at Amager, West, and the Hillerod transfer station. An
identical Philips system was under consideration for the Roskilde Volund
plant as well. In theory, the system could be used throughout Denmark to
the advantage of all.
Relevant information is displayed (see Figure l4-l4d) on digital
readout devices. The single operator can process 120 vehicles per hour if
both scales are used simultaneously. The scales can be used automatically
at night when the scale house is unmanned. Opening the plant gate and
weighing the vehicles can be controlled from inside the plant at the main
control room with use of television cameras (see Figure l4-l4c). Truck
entrance and tipping activities are shown in Figures l4-l4e, f, and g.
Waste Storage and Retrieval
Amager has a pit 48 m (158 ft) long, 17 m (56 ft) wide, and 13 m
(43 ft) deep. The capacity to the tipping floor door level is 10,000 m3
(13,462 yd3). However, with refuse piled against several doors and by
piling refuse against the wall to the furnace, the maximum capacity can be
doubled to 20,000 m3 26,924 yd3). This converts to 3.5 days maximum
storage. The specific weight or density is 0.2 to 0.3 tonnes/m3 (336 to
505 pounds/yd3).
The 11 refuse doors are described as double hinged flap doors
8.0 m (26.4 ft) high, 3.8 m (12.5 ft) wide, and 122 mm (4.8 in) thick.
They are operated hydraulically. The tipping configuration was designed
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48
carefully to allow for a door and also to permit full view of tipped
refuse by the crane operators (see Figures l4-15a and b).
The West pit is much deeper by comparison than Amager. The West
pit bottom is 4.0 m (13.2 ft) above sea level while Amager is 3.7 m
(12.2ft) below sea level.
There are two fire cannons located around the pit at the hopper
level. They also have four hoses that are 30 m (100 ft) long. The local
fire department is called for the few fires that cannot be controlled by
plant personnel.
The plant has two cranes (one active and one often in reserve),
manufactured by Thomas Schmidt A/S. During the day, the second crane
mixes incoming waste to a fairly uniform calorific content. Only at night
is this crane truly in reserve.
Comment: When planning the number of cranes, there are a number
of factors that could necessitate having a mixing crane. Some
are seasonal changes with low calorific value (wet vegetation loads),
a or high calorific material (truck loads of tires, industrial plastics
etc.)- If in the future, industrial wastes might augment household
waste, space should be set aside during the initial construction for a /
mixing crane.
Each crane is rated at 10.5 tonnes (11.5 tons). Television
cameras aimed at the hopper assist the crane operator in setting the drop
position over the hopper.
When both cranes are functioning, they can together put up to 50
tonnes (55 tons) per hour into hoppers. The cranes are equipped with Sven
8 m^ (10.8 yd3) star grab polyp buckets (Figure l4-l6a). Each normally
handles 2.5 tonnes (2.75 tons) of refuse per lift. The maximum net load is
4 tonnes (4.4 tons).
The Amager cranes were initially a source of numerous problems.
Esentially the cranes and bucket were undersized. The bearings on the
polyp bucket often failed. The crane hoist motor would burn out for no
apparent reason. Hydraulic leaks from the polyp due to high temperatures
on the hydraulic coil were frequent.
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49
.Centered Crnne
Control Room
/I
FIGURE 14-15a. TIPPING DOOR THAT CAN CLOSE.
UNOBSTRUCTED VIEW OF PIT BY
CRANE OPERATOR
FIGURE 14-15b. CRANE OPERATOR CONTROLLING
POLYP TOWARDS HOPPER
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50
FIGURE 14-16a. SVEN POLYP GRAB AT COPENHAGEN:AMAGER
GOING DOWN FOR ANOTHER LOAD
lifting cables
open and close cable
hydraulic motor
FIGURE 14-16b. SCHEMATIC OF POLYP
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51
After 2 years, most of the problems were solved by a series of
corrective steps. Bearings twice the original size were installed. The
German electric motors were replaced by larger Siemensmotors. Better seal
packing and gaskets reduced hydraulic oil leakage.
However, the original design did have beneficial features. In
contrast to the old Gentofte plant where cables would break every 2 weeks,
the Amager cables would last about 1 year. The difference was for several
reasons. First, a strong special German wire cable was always used.
Second, the bucket was always hydraulic and not mechanical.. Third, the
polyp is controlled with a hydraulic motor located inside the bell of the
polyp top. There is a sensor so that when the polyp is more than 45
degrees from its level position, it switches off and refuses to permit
further movement that might snag the cables. Fourth, the polyp has
additional stability due to the four lifting strands as compared to two
strands in some less expensive system as shown in Figure 1i<-l6b.
Based on the many crane problems at Amager and the success in
curing them, West was more properly designed and has had fewer problems.
This revised cable and polyp system has worked exceptionally well and is
considered well worth the extra money. Incidentally, Volund was so
impressed with the Sven polyp that Volund bought Sven in 1977.
Furnace Hoppers, Feeders, and Swivel Gate
The hopper dimensions at its top opening are 6 m (20 ft) by 6 m
(20 ft). Farther down, at the hopper bottom, the dimensions are 2.3 m
(7.6 ft) by 1.15 m (3.8 ft). Its height is 6 m (20 ft). The walls are
made from 8 mm (.31 in) plain carbon steel.
Sometimes instead of a steel hopper, Volund will install a
concrete hopper. Concrete is cheaper and quieter.
The filling chute has a slightly larger width dimension than the
hopper: 2.3 m (7.6 ft) by 1.15 m (3.8 ft). It too is made of 8 mm
(.31 in ) steel.
The swivel gate or damper is located in the chute. It is opened
when refuse falls on it and closed when no refuse is above it. Its
function is to prevent burnback.
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52
The damper's dimensions are 2.58 m (8.5 ft) by 1.26 m (4.16 ft)
and is 10 mm (.39 in) thick. The 2.3 m dimension gradually increases to 2.7 m
(8.9 Ft) near the furnace entrance so that jamming is minimized.
Volund typically installs chutes with only refractory lining.
Except for flowing material, the hopper should always be empty. There
should be no refuse above this kind of damper to interfere with its
closing. With proper crane operator training and performance, burnback can
be minimized. Officials believe that water cooled jackets, besides being
unnecessary, have more costs of operation and maintenance.
Primary (Underfire) Air
The plant designers had been of the opinion that the air intake
should be at the hopper level for better control of odors from the pit. As
someone stated, "if the primary air is taken from the top of the bunker
(higher and above the crane), you could smell the air on the tipping
crane control room-hopper floor".
The intake was thus located at the hopper level as shown in
Figure 1*1-17. This resulted in a very dusty floor and atmosphere around
the hopper. But more important the dust raised by the falling refuse
would clog the vent and accumulate in the ductwork. The air intake was
later raised about 3 m (10 ft) to the level shown in Figure 14-18. The
entrance at this higher position should (1) better remove smoke from any
pit fires (2) provide better ventilation in the summer, (3) be freer from
dust and (4) permit a better environment.
The air is then pulled in and down by the Nordisk 1490 rpm fan
which can pull 45,000 Nm3/hour. The temperature is assumed to be 30 C (86
F) in the summer. The static pressure is 230 mm water.
Primary air is delivered to four hoppers under the grates:
Drying Grate (one hopper), Ignition Grate (one hopper), and the Combustion
Grate (two hoppers). There is one large damper per furnace that is set
only once. However, each of the four hoppers (plemum sections) has its
own separately controlled damper that can be adjusted from the control
room. Each hopper's pressure reading is sent to the control room, but it
is not recorded.
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54
Raised Position
Original Position
FIGURE 14-18. ORIGINAL AND RAISED POSITION OF THE
PRIMARY AIR INTAKE
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55
There are two types of fan drives available for designs: (1) fan
belt and (2) direct. The direct method is not normally used except for
large induced draft (ID) fans just before the chimney. In the future, the
Amager plant capacity can be raised (other systems permitting) simply by
changing the belt. Assuming that the electric motor speed does not change,
then the air pressure can be lowered and a higher quantity of air can be
passed.
Volund usually specifies a fan to be operated at a point
situated in the middle of the capacity curve e.g. lower r.p.m. than the
maximum allowed. In case more air is necessary, for speed can be
increased.
One other point is that when Volund dimensions a fan they ask
for a certain amount of air at a certain pressure. In case the pressure
is lower than necessary more air can be transported by the fan. These two
factors are proportionally to each other e.g. higher pressure = less air.
There are now very few problems with the primary air system. The
blades are self cleaning. Sometimes when the hopper floor area is hosed
down with water, the mist would be sucked into the vent. The moisture
would mix with the dust (from crane discharges into the hopper) and form
deposits. Now every 6 months, the ventilator is opened and air is blown
through the duct.
Secondary (Overfire) Air
Volund furnaces have three (3) sources of secondary air that can
be blended for proper operation. Sometimes (1) oxygen rich refuse bunker
air (2) normal boiler room air or (3) oxygen poor flue gas recirculation air
may be needed in varying amounts when the refuse heating content varies.
Refuse Bunker-Oxygen Rich Air
Amager can pull its cool oxygen-rich secondary air from the refuse
bunker. This is slightly different from West where both primary and
secondary air is pulled from the boiler room. The Nordisk Ventilator forced-
3
draft 150 Hp belt-driven fan, running at 1,670 rpm, can pull 35,000 Nm hour.
The temperature is assumed to be 30 C (86 F) and the static pressure is 460
mm water.
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56
The air is sent to two manifolds on each side of the furnace and
above Grate III. Each manifold a set of nozzles as shown below.
o
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Secondary Air Nozzles
Figure 14-19 shows the sidewall jets.,
Flue Gas Recirculation - Oxygen Poor Air
Amager formerly (during only the first year) used recirculated
flue gas as secondary air. The air was drawn from the flue gas leaving the
hot electrostatic precipitator. See the previous Figure 1U-1.
Another Nordisk Ventilator forced draft fan, this one at 150 Hp,
was belt driven at 1,460 rpm. The fan is rated at 45,000 Nm3/hour and
delivered the 300 to 350 C (572 to 662 F) hot flue gas at 220 mm water
pressure.
Many Volund units are built to permit use of either or to permit
blending.
Boiler Room - Oxygen Normal Air
The use of ambient boiler room air at 30 C (86 F) or
recirculated flue gas air, 138 to 177 C (280 to 350 F), is determined by
basic furnace design and the refuse lower heating value (LHV). Assume that
the furnaces were nominally designed for refuse with a LHV of 2,000
kcal/kg. If the LHV is well over 2,500 kcal/kg, air rich in 02, might shock
the refractory and cause the Carborundum bricks to grow and then spall.
Therefore, if the refuse is "hot", then recirculated flue gas air, poorer
in 02, should be used. In contrast, if the refuse is "cool" or wet, then
ambient boiler room, rich in 02, should be used.
Of the European vendors visited, Volund is the only manufacturer
known to us to use recirculated flue gas.
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57
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58
The recirculation flue gas fan has a damper that is
automatically controlled. It sends a larger or smaller quantity of the
flue gas back to the furnace depending on the furnace combustion
temperature. The dampers are adjusted so that the furnace temperature is
always 900 to 1,000 C (1652 to 1832 F).
At Amager, where the refuse is cooler, 1,800 kcal/kg (3240 Btu/pound),
than at West, they now use both refuse bunker primary air and boiler room
secondary air. Refractory life has improved. The boiler room air is now put
through the back wall where the flue gas recirculation air had been previously
inserted.
Flue Gas Fan
An induced-draft Nordisk Ventilator flue-gas fan is located
between the electrostatic precipitator and the chimney. It is necessarily
the strongest fan and can pull 107,000 Nm3/hour with its 220 Hp motor. It
too is belt driven but at a lower speed of 1010 rpm. It delivers the flue
gas at 170mm water pressure to the chimney. Flue gas temperatures range
from 300 to 350 C (572 to 622 F). The fan has a damper connected with a
regulator which holds the vacuum in the furnace constant at all times.
Fan Summary
Table 14-2 presents key design parameters for the four fans: (1)
F.D. primary air, (2) F.D. secondary air, (3) I.D. flue gas recirculation,
and (4) F.D. flue gas recirculation.
The plant people report that the furnaces each with four fans
have experienced only minor maintenance.
Assuming the maximum refuse calorific value to be 2,500 kcal/kg
(4500 Btu/pound), the theoretical air is 3.01 m3/kg (234 ft3/pound). After
combustion, the theoretical combustion flue gas is 3.78 m3/kg (294
ft3/pound), while the actual is 5.3 to 6.8 m3/kg (412 to 528 ft3/pound).
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59
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Furnace Combustion Chamber
The original Volund designers had two seemingly opposite design
considerations. First, the design should ensure proper drying out of the
wet refuse. Therefore, there is a desire to use a gas counter-flow to the
waste flow as shown in Figure H4-20a.
On the other hand, there should be good burnout of putrescibles
and carbon. Therefore, the gas flow should parallel the waste flow as in
Figurel4-20b.
A compromise suggested by other vendors would be to simply have
the flue gas exit centered over the grate as shown in Figure lH-20c.
The Volund simplified answer is to put a wall above the grate
and to send some of the gases back toward the feed chute and the other
gases toward the ash chute as shown in Figure l4-20d.
The more elaborate answer from Volund is to attach a rotary kiln
at the end of the furnace grate as shown in Figure l4-20e. Here some hot
gas returns back toward the feed chute to help dry the incoming waste.
Also, the other gases continue flowing with the waste out of the grate
area and into the rotary kiln. The heat supports further combustion in
the kiln to consume almost all of the putrescibles and unburnt carbon.
This configuration, known as the two-way gas grate and rotary
kiln system, is the design at both Amager and West. The schematic (see
Figure 14-21) for Frederiksberg (1931*) shows the basic configurations. To
restate, the original two Volund plants (Gentofte and Frederiksberg)
successfully served Copenhagen for UO years.
Burning Grate (Forward Pushing Step Grate)
Information, for the record, regarding the Volund grate is
distributed between the trip reports 14 and 15 (Amager and West). Part of
this section is taken directly from a technical 1969 paper written by Mr.
E. Blach, former Volund Chief Engineer, entitled "Plants for Incineration
of Refuse".
"This grate construction is built up of several grate
sections, each separated by a vertical grate transition bar. The
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61
VWundM
FIGURE 14-20. GENERAL DESIGN CONFIGURATIONS FOR VOLUND FURNACES
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62
FIGURE 14-21.
FURNACE DESIGN (TWO-WAY GAS GRATE AND ROTARY
KILN) AT THE OLD (1934) FREDERIKSBERG PLANT,
DISMANTLED IN 1970
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63
ratio of size between the individual grate sections and grate
transitions is determined by the composition of the refuse.
Figure 14-22. The individual grate section is built up of
lengthwise-placed sections of 180 to 300 mm wide laid up with an
inclination of 18-15°. Every other of these sections are fixed
and every other are moveable, and each section is built up of a
through grate bar, which is welded up, on which a number of
grate blocks of specially alloyed cast iron are fitted, which
are in turn filled up with loose grate bars of cast iron.
Figure 14-23. The moveable sections are driven
hydraulically by a transverse driving shaft placed under the
grate, which is connected to the individual sections by pendulum
driving bars. From a neutral position, the movement in forwards
stroke is slowly raising, forward going, and then lowering and
backwards going. In the .backwards stroke, the movement is
slowly lowering and backwards going and then raising and
forwards going.
Along the side of grate sections, which are built into the
wall of the furnace, there are a number of side sealing beams,
which through building in springs give the grate sections a
transverse flexible assembling.
Figure 14-24 is a drawing included in one of Volund's first
patents. The first grate section acts as a feeding and
predrying grate and apart from the last part of the transition
bar, it is covered with grate plates. Ignition and the first
part of the combustion take place at the first transition and on
the second grate. The final combustion and burnout takes place
on the third grate, and calcining and cooling of the clinkers
begin at the last part of the tjiird grate and continue on the
subsequent clinker chute.
The layer of refuse is 300 to 500 mm (12 to 20 inches). The
moveable grate sections give a lifting, moving, and turning
movement in the lower half of the layer so that the combustion
air, which in a regulated way is supplied from below, can get to
all parts of the layer. At the transition bars, there is a
supplementary turning, mixing, and air supply.
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Oct. 1, 1935. A CHRISTENSEN 2,015,842
FURNACE WITH GRATE FOR COMBUSTION OF REFUSE OF ANY KIND
Filed Nov. 5. 1932
INVENTOR
FIGURE 14-24. ONE OF THE EARLIEST VOLUND PATENTS
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67
Volund supplies furnaces with either three or four separate
grates. Amager has three grates per furnace.
Each of the furnaces has two operating hydraulic pumps. At some
other installations, an additional hydraulic pump is used as a standby.
Each pump's capacity is 47 liters/minute (12.4 gallons/minute). Each pump
has a 15 Hp motor. The resultant pressure is 70 kg/cm^ (1,160
pounds/in^). The plant has one 600 liter (160 gallon) hydraulic oil
storage tank.
Each of the first three grates have five hydraulic cylinders
with cylinder bases of 80 mm (3.15 inches) and strokes of 130 mm
(5.1inches). The stroke frequency is three strokes per minute.
Having three grates means that there are two steps. The height
between Drying Grate I and Grate II is 1 m (3 feet). Between Grate II and
Final Grate III, the height is 2 m (6 feet).
The final step, from the grate system to the rotary kiln, is 1 m
(3 feet) high. The grate exit to the rotary kiln is shown in Figure 14-25.
The earlier Volund plants (1930's) had grates with an angle of
23 degrees and a conical rotary kiln based on the refuse composition of
the "poor times". In the beginning of 1960 the grate inclination was 20
degrees and the kiln at a choice of conical or cylinder depending on the
town and the living standard of people.
In 1965 the rotary kiln became cylindrical and the grates were
constructed at 15 degrees. This is the present situation.
Amager plant officials estimate that the individual grate bars
will last about 15,000 hours. Stated in another manner, on the average 100
percent of the bars are replaced every 15,000 hours. The grate bars last
20,000 hours at West.
Compared to West, the amount of small-sized inert (ash)
particles is more at Amager. Perhaps Amager's increased volume of inerts,
less grass and more home furnace ash, contribute to Amager's shorter grate
life.
The ash leaving the Amager plant is often smaller than the West
ash because any large clinker at 800 C (1472 F) from the rotary kiln
falling into a bath of "cold" water will explode into small fragments.
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68
FIGURE 14-25.
GRATE FURNACE EXIT INTO A. ROTARY
KILN AT ONE OF VOLUND'S PLANTS
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69
All grate frames, bars, and grates are made from a material
called "Meehanite HR." It is ductile but has a minimum 350 Brinnell
hardness. The side seals are made from "Nicromax". Due to the moving and
rubbing surfaces, this can be less ductile but very hard. Occasionally
tramp metal (usually iron) will fall on the first grate and break a bar.
All three grates have a 2.7 m (8.9 feet) width. The grate stroke
is 130 mm (5.1 inches). Roughly 23 percent of the grate area is open for
combustion air to enter. The length and area of the three grates are as
follows:
Drying Grate 1 Burning Grate 2 Burning Grate 3
Grate Length (m) 2.5 2-° 5.0
Area (m2) 6.75 5.4 13.5
Furnace Refractory Wall
Volund furnace walls are refractory lined (and not lined with
water tube walls) inside a steel framework.
The six furnaces for both Amager and West (three each) were
designed and built at about the same time. (West later added a fourth
unit).
Volund originally chose Hoganus, a high-quality and expensive
refractory, for its flame wall lining. The bricks themselves were not a
problem. The difficulty, however, was that there were not enough anchors
between the iron structural framework and the bricks. In addition, the few
original anchors were not properly welded and broke during thermal
expansion. Also, ash was accumulating or "slagging" on the walls.
As a result of the several problems, the furnace walls were
rebuilt. Fortunately the warranty period was still in effect. More anchors
were added. The welding technique was changed.
To cure the ash slagging problem, silicon carbide was added to
the walls above the grate .5 to .7 m (1.5 to 2 feet). However, where the
flame is hottest and the 02 levels the greatest, the SiC is to be avoided
so that it does not oxidize. Hence, the lowest wall areas and up a little
bit in the middle side wall are left with Hoganus chamotte bricks exposed.
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70
Volund officials believe that, with proper anchoring, a
refractory wall furnace is less expensive and more reliable than a water
tube wall furnace. Having learned from the Amager experience, they now
specify a wall shown below:
Plastic Silicon Carbide,
beginning .5 to .7m
above grate
Flame
Thick Chamotte Bricks
Refuse Bed
Porous Chamotte Bricks
Moler Blocks
Steel Plate
Furnace Room
225 60 150 mm
The Moler blocks near the outside wall are unique to Denmark.
The clay is literally quarried or carved out of the deposit in the final
shape. (There is no normal mixing and blending of clays.) The blocks are
simply fired. The brick dimensions of 23.4 x 11.3 x 6.2 cm (9.2 x 4.4 x
2.4 inches) weigh 1.2 kg (2.6 pounds). This is slightly heavier than many
insulating fire bricks but much stronger.
Volund does not report the furnace volume or heat release area
since the wall enclosures are not designed for heat transfer, as are the
walls of a water-tube wall furnace.
The furnace roof is always arched if the span is less than 3 m
(10 feet). However, for wider roof sections, a steel structure is built
with many hangers. Specially shaped Chamotte bricks are then suspended
from the anchors. Then granulated Moler particles are spread on top of
the steel and bricks. Finally, rock wool is laid on top of everything.
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Rotary Kiln
The rotary kiln is seen in its relationship to other key furnace
parts in a plant schematic of the now dismantled Gentofte plant (see the
previous Figure 14-7) that served northern Copenhagen so well for 40
years. The basic design (with the exception of major modifications to the
boiler and air pollution control equipment) remains the same today. To
repeat, again from Mr. E. Blach's paper:
"Pre-drying, ignition, and the first part of the combustion
takes place on the grate system ..., but then the refuse slides
into the rotary kiln, where the final combustion and burning out
takes place.
While in operation the rotary kiln turns slowly and thus
creates a perfect overturning of the burning refuse. The
movement makes the refuse travel a very long way and thereby
stay for a long time in the kiln. The system operates with the
so-called divided flue gas/combustion air circulation, e.g. the
primary combustion air is divided into two after having passed
through the layer of refuse on the grates, one part passing
through the rotary kiln and one part passing over the layer of
refuse on the grates up to the top of the furnace, from where it
is brought back to the after burning chamber through the
previously mentioned connecting flue gas passage coming from the
rotary kiln.
Besides primary air, secondary air is added over the grate
sections as well as the rotary kiln in order to ensure for
v
certain that the flue gases are fully burned. By adding a
surplus of primary and/or secondary air a cooling of the
combustion can be achieved. But this cooling function can be
achieved better and more effectively by using a flue gas
recirculation system, e.g., cooled flue gas is brought back to
the combustion zone, over the grates, and at the rotary kiln.
While in operation, this cooling function is done automatically
so that the temperature is kept at 900°- 1,000° C.
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The rotary kiln is built up of an outer heavy steel plate,
which are lined with wear resistant fire-proof bricks on the
inside laid up and built on an insulating layer direct up to the
steel plate. The ends the kiln are furnished with special
sliding seals and transition sections. The whole construction
rests on two sets of running and guiding wheels, which at the
same time act as friction pinion, activated by hydraulic motors.
The speed of rotation can be regulated variably between 0 and 15
r.p.h.
The grate/rotary kiln design is used for capacities from 5
t/h to about 20 t/h, but can be built also in larger plants."
The carbon steel shell (see Figure 14-26) has an inside diameter
f-
of 4 m (13.2 feet). With the addition of refractory, the inside diameter
is reduced to 3.4 m (11.2 feet). Each kiln is 8 m (26.4 feet) long. Volund
will build kilns up to 10 m ( 33 feet). The volume is 73 m2
The kiln is sloped downward-at a 3 degree angle and revolves
upwards of 12 revolutions per hour (rph). It however, normally revolves at
6 to 8 rph. IF the furnace operator is told by the crane operator that the
refuse is wet or if he sees a disturbance in the kiln, he can easily lower
the kiln speed.
The original configuration had two support rings, two support
rollers, one thrust roller, and two drive support rollers all made from
high tensile-strength steel castings (see Figure 14-27).
Later, officials decided that large spacing between rollers was
permitting alternatively excessive compressive and tensile forces. Thus
open spaces would develop in the lining depending on where the brick
section was on its rotation. Eventually bricks would be either crushed or
would fall out.
The two hydraulic motors per kiln are rated at 3 kg-m (21.8
foot-pounds) and have a maximum speed of 76 revolutions per hour or 1.27
rpm. The nominal reduction is 1:800.
The refractory bricks are anchored onto the steel shell. Moler
refractory was originally specified to be placed next to the steel shell.
Then next to the Moler refractory, Chamotte bricks of 36-55 percent Al2C>3
content are used to line the inside of the kiln. The composition is 85
percent SiC at the inlet.
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FIGURE 14-27.
TWO SUPPORT RINGS OF A
VOLUND ROTARY KILN
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To some extent, because of very high temperatures, the kiln is
self-cleaning. Slag does not normally accumulate on refractory walls.
However, at some other Volund plants, slag "rings" occasionally form
within the kiln. This only occurs if the kiln is conical and the
temperature is very high. Interestingly, this slag ring can gradually
move down the length of the kiln. It eventually disappears.
Everytime the furnace is stopped and cooled enough , the kiln is
inspected. Occasionally several rings of brick are replaced. Finally in
1977i after 7 year's (1*2,000 hours) operation, the kiln was completely
rebuilt at a cost of 150,000 D.kr. ($25,960).
During this major change, the brick used was respecified.
Instead of the very porous Moler brick, which was crushed under
compressive pressures once per revolution, a harder inner brick was used.
Some insulation quality was sacrificed but the temperature just outside
the kiln rose only 2 C (3.6 F) from before.
After Burning Chamber
Flue gas leaves both the grate section in an upward direction
while flue gas also leaves the kiln and rises. Occasionally slag will form
on the 45° slanting lower surface in the mixing chamber above the rotating
kiln (see Figure 1U-1).
Boiler (General)
The boilers at both Amager and West were designed and built
under Volund patents. The Amager units consist of a refractory walled
furnace, an afterburning chamber and then followed by the Volund boiler
(see Figure 14-28). Thus, Volund units are not "water wall incinerators."
Later Volund plants in Japan and Aalborg have Eckrohr vertical
water-tube wall boilers completely separate and following the combustion
furnace. The Eckrohr (translated "corner-tube") boilers were built under
a license from Professor Dr. Vorkauf of Berlin, W. Germany. We later heard
that roughly 180 of these boilers have been installed on refuse-fired
energy systems. When asked why Volund often now uses the Eckrohr boiler
instead of the traditional Volund boiler, the reply evoked the Eckrohr
features - features that seemed popular in several other places over
Europe.
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FIGURE 14-28. AFTER BURNING CHAMBER AND BOILER
AT COPENHAGEN: AMAGER
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77
The four corner tubes are used not only to carry downstream
water but also they provide structural support for the whole
boiler, thus reducing construction costs.
The heat transfers rate is excellent.
The circulation pattern is good.
It has high efficiency.
It is a natural circulation boiler.
The market for energy demands slightly higher temperatures at
West than at Amager as follows:
West Amager
Energy form Overheated water hot water
Water temperature leaving
plant* 160 - 170 C 115 - 120 C
Water temperature return-
ing to plant* 140 C 70 - 75 C
284 F 158 F
Heat output 21.5 goal/hour 20 goal/hour
Pressure (working) 16 kg/cm^ 6 kg/cm^ - 7 kg/cm^
225 psi 85 psi
The key reason for higher temperatures at West (and not Amager)
is that an early customer was the Copenhagen County Hospital that needed
hotter water for sterilization and air conditioning. So often, we have
observed that the initial customers will dominantly effect long term energy
configurations.
The amount of combustion gas entering the boiler was provided
but as a function of refuse lower heating values.
* Actual temperatures will vary from these average temperatures
depending on the time of year.
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Lower Heating Value, Amount of Gas,
kcal/kg Nm3/hour
1,000
2,000
2,500
33,000
77,000
98,500
Lowest
Average
Highest
The combustion gas inlet temperature to the boiler is around 800
C (1,^72 F). The outlet combustion gas temperatures range from 280 to 350
C (536 to 662 F).
Details of heating surface area are shown below with the codes
also appearing in Figure 1U-29:
Units
First Pass Radiation Wall (R1)
Second Pass Radiation Wall (R2)
Third Pass Radiation Wall (R3)
Regular Radiation Walls
Scott Walls (S1 and S2)
Total Radiation Walls
Convection Section (C)
Economizer Section (E)
Total Heating Area
Boiler cleaning has been an experimental matter at Amager. They
tried acoustic (sonic) cleaning. They also tried vibrating (mechanical
rapping) the tubes. Now for the convection and economizer sections,
falling steel shot is used routinely. On shutdowns; the first, second,
and third open radiation passes are manually brushed clean.
Mr. Pinto referred several times to their corporate position of
not participating in the municipal waste to very high temperature steam
systems. They will not sell anything that would likely have corrosive
failures within a year or two. As Mr. Pinto stated, "It's not fair (to
the customer) to build a system that might fail".
Volund later clarified its position with the following statement.
"The highest temperature in any of the Volund plants is 490 C at
Ortvikens Papperbruk, Sundsvall, Sweden. The plant which is
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mainly for bark incineration is equipped with an Eckrohr boiler,
which produces steam at 425 C, and in a separate overheater
the temperature is brought up to 490 C - 67 ato.
Sundsvall, Sweden - steam: 28.5 t/h - 67 ato - 490 C
Itabashi, Japan, - steam: 28.9 t/h - 16 ato - 203,4 C
Nishinomiya, Japan - steam: 14.6 t/h - 18 ato - 208,8 C
Kawagushi, Japan - steam: 15.8 t/h - 16 ato - 203,4 C
Kohnan, Japan - steam: 35.9 t/h - 16 ato - 203,4 C
Boras, Sweden - steam: 16.5 t/h - 10 ato - 285 c
If a customer wanted excellent burnout rates, wanted 500 C
(932 F) steam, and showed high interest in Volund; then Volund might
submit a bid. Volund could propose to raise the steam temperature
to 300 C (572 F) by burning refuse. The steam would then be input
to a topping off fossil fuel (likely oil) boiler to raise it to the
500 C (932 F) level demanded.
Convection Section
An interesting corrosion problem developed at Amager, but not
West, due to the temperature of the entering feedwater. Amager's
returning warm water is about 70 C (158 F). The manufacturer had warned
the system owner that this would put the metal temperature at the entrance
to the convection boiler section in a dangerous "dew point corrosion"
temperature zone. Another cause for the dew point corrosion was the many
early (first 2 years) shutdowns due to crane malfunction.
Thus, with accepted forewarning, the system was constructed.
Some of the lower convection section bundles were replaced after 30,000
hours because of dew point corrosion.
Later when the complete line was overhauled after 42,000 hours,
the entire convection system was replaced. There are thicker tubes on
the bottom and thinner tubes on the top. Officials now hope that the
unit can go for 60,000 hours without corrosion rupture.
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Economizer
The economizer and its steel shot cleaning system both were
supplied by Eckstrom of Stockholm, Sweden. As at West, the Amager
economizers were fin tube with small spaces. The spaces and corners became
so clogged with flyash and steel shot, that they will have to be replaced.
Because of the clogging, the economizers at both Amager and West have set
the overhaul schedule for the whole plant. Until the economizers are
replaced, the unit will continue to shutdown every 1,500 to 2,200 hours.
The manufacturer's original recommendation of shutdown for inspection and
cleaning every 3,000 hours would have been mainly to restore efficiency.
The economizer is cleaned manually with brushes.
It is likely that the electrostatic precipitator corrosion
problems experienced were caused by the clogged economizer not doing its
job, i.e. lowering economizer flue gas exit temperature to below 300 C
(572F).
Unfortunately, shot cleaning was not in the original design.
Therefore, on retrofit, the falling shot was downconcurrent to the flue
gas. In future economizer designs, both the gas flow and the steel shot
flow will be downward.
Boiler Water Treatment
The boiler feedwater is thoroughly treated at the adjoining
power plant. Treatment includes deaerating, desalting and demineralizing.
Cofiring
Cofiring is not a significant practice at Amager. However, and for
the record, in 1931 Volund did cofire Gentofte with bark and coal in a 3-1/2
tonne/day unit. In late 1977, Volund had a proposal to a Polish city that
included cofiring of refuse and coal.
The reader is referred back to the Waste Input Section where
there is a discussion about original inclusion of sewage sludge and waste
oil. Currently there is some sewage sludge coarse ridlings put directly
into the pit for mixing with refuse. No appreciable waste oil is cofired.
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ENERGY UTILIZATION EQUIPMENT
Figure 14-30 shows the refuse burning plant in the foreground
with the larger conventional power plant, owned by Copenhagen Gas and
Electric, in the background. The refuse plant is a base load plant. The
conventional plant, being the peaking plant, can adjust its operations to
ensure steady energy delivery depending on season.
The refuse plant's hot water is sent to the electricity plant,
but it is not used to make electricity. Rather, the hot water is combined
with the electricity plant's waste heat and together they supply the
Amager Island district heating network.
The Amager refuse plant sells its hot water for a lower price
than does the West plant for several reasons: (1) the water temperature is
lower at Amager and hence contains less energy per pound; (2) the single
distribution pipe to the power plant is only a couple of hundred feet; (30
Copenhagen Gas and Electric Authority (CGEA) handles the district heating
distribution, so the refuse plant has no distribution expenses, and (H)
the refuse plant's energy competes with the CGEA plant's waste heat.
Roughly 1.2 Gigacalories (4.76 million Btus) can be added to water
per tonne of refuse burned. At Amager, the annual average sale price to CGEA
varies from 55 to 60 D.kr. per Goal ($2.40 to 2.62/million Btus). The formula
is somewhat unique. If the CGEA electric power plant is working and producing
its wdn waste heat, then the energy value paid to the refuse plant is 60 per-
cent of the comparable oil price for the same energy. However, if the electric
power plant is not in operation, then the refuse plant receives 100 percent of
the comparable oil price. All calculations are based on heating value and not
on volumes of water.
Under this arrangement, the refuse plant sold 70 percent of its
production during 1975-1976. The percentage has been increasing from year
to year.
Belysningsvaesen or Copenhagen Gas and Electric Co. was the
consultant for Amager Incineration and was in charge of the project as
their experience power stations was assumed to be of value.
The plan with Amager Incineration was to sell district heating
to the communities forming the partnership. The Power Station next to
Amager Incineration has a surplus of waste heat in much more quantity than
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FIGURE K-49. COPENHAGEN: AMAGER'S REFUSE FIRED ENERGY PLANT IN THE
FOREGROUND AND THE OIL (OR COAL?) FIRED PLANT IN THE
BACKGROUND
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the Incineration plant. Thus to avoid competion and duplicate pipelines, an
agreement took place where Amager sells the heat to the Power Station.
Nevertheless by 1982 the Amager plant shall have installed Unit No. A and
all the heat produced can be sold as a pipeline under the canal to the
Copenhagen city, where a pipeline will be installed in the meantime and
better prices for the sold heat will be achieved.
Heavy insulated water pipes are shown in Figure l4-31a. The
pumps used to send steam to the combined district heating system are shown
in Figure 14-31b.
Amager produces hot water at 115 to 120 C (239 to 248 F) at 6
kg/cm2 (85 psi). As stated before, this is lower quality hot water than
the superheated water at West. Amager sends its share of the energy to
the power plant which then distributes it to the district heating system
shown in Figure 14-31C. Of the total energy sold, 50 percent goes
directly to household radiators. The other 50 percent transfers its
energy through water-to-water heat exchangers before going to radiators..
The total energy delivered to the district heating system is
shown in Figure 14-32. Note that the summer base load is usually 8,000
Gigacalories while the winter peak load is around 20,000 Gigacalories.
Presumably a few industries, hospitals, etc. provide the base load in the
summer.
The 1975-1976 energy sold amounted to 188,253 Gigacalories
(746,988 million Btus) for a revenue off 4,877,703 D.kr . ( $8 1 2 , 950 ) .
Dividing revenue by quantity results in an average sale price of 25.91
D.kr./Gcal (1.09/million Btus).
Since the hot water is "priced" at $2.40 to 2.62 per million Btu
and the "average revenue" over a year's time is only $1.09 per million
Btu; it is assumed that only 44 percent of the hot water generated is sold.
Having monitored events at the Nashville (Tennessee) Thermal
Transfer Corporation (NTTC) we must point out to the reader that more
revenue derives from district cooling than from district heating. We ask
the retorical question, "Is there a future for district cooling for
European systems that will even the seasonal revenues from energy
production and raise annual revenues?"
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JB>
FIGURE 14-31a.
INSULATED HOT
WATER PIPES
LEAVING BOILER
AT AMAGER
FIGURE 14-31c. MAP OF
DISTRICT
HEATING
NETWORK
OF AMAGER
ISLAND
FIGURE 14-31b.
PUMPS TO SEND HOT WATER TO
THE POWER PLANT WHICH SENDS
THE HOT WATER TO THE DISTRICT
HEATING NETWORK AT AMAGER
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Gigacalories
2000 4000 6000 8000 10000 12000 14000 16000 18000 20000 22000 24000 26000
1972
-___ MAJ
1973 JUNI
JULI
AUGUST
SEPTEMBER
OKTOBER
NOVEMBER
DECEMBER
JANUAR
FEBRUAR
MARTS
1974
JULI
AUGUST
SEPTEMBER
OKTOBER
NOVEMBER
DECEMBER
JANUAR
FEBRUAR
MARTS
1974 APRIL
MAJ
1975
JULI
AUGUST
SEPTEMBER
OKTOBER
NOVEMBER
DECEMBER
JANUAR
FEBRUAR
MARTS
1976
MAJ
JULI
AUGUST
SEPTEMBER
OKTOBER
NOVEMBER
DECEMBER
JANUAR
FEBRUAR
MARTS
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More of Mr. Blach's Comments on Heat Exploitation
"It will always be economically profitable to exploit the
heat from an incinerator plant, whenever possible.
The heat can be used for district heating, various
industrial purposes, drying and burning of sewer sludge or other
sludge products, and for production of electricity.
If the heat cannot be exploited, other arrangements must be
made to cool the 900-1000 C(1652 0 1832 P), hot flue gas to
about maximum 350 C (662 F), before it is led into the
precipitator and the chimney.
Such a cooling of the flue gas can be done by adding air,
water spray, a combination of water spray and air, or by letting
the flue gas through a waste heat boiler and then cool the water
or steam.
Initial expenditures of plant as well as operational costs
for the cooling plant with air, water spray, or a combination
are just as high as the costs of an actual plant for heat
exploitation with a possible supplementary air cooler. The sale
of heat, therefore, is an actual working income, which
contributes essentially to the operation of the plant, even with
regard to the extra costs for repair caused by wear and
corrosion in the convection part of the boiler part.
Least profitable is the production of electricity as the
costs of high pressure boilers and turbines are too high and the
efficiency too low compared with the low price at which the big
power stations can produce the electricity. There is a great
need for drying and burning sludge, and the use of waste heat
for the purpose can be expected to be common in the future. Sale
of heat for district heating or industrial purposes has,
therefore, up to now been the solution which technically and
economically has shown the best results."
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POLLUTION CONTROL EQUIPMENT
Air Pollution
Both at Amager and West, Rothemuhle two field electrostatic
precipitators (ESP) are the sole means of air pollution control now in
efffect. Plant officials were initially hesitant about this and had
thought of the need to add a mechanical cyclone collector after the ESP.
They wanted to make sure that the larger paper particles would for certain
be captured. Therefore, they mandated that room should be available for
adding the cyclones later if necessary. The space is outlined with dash
lines in the previous Figure 14-1. As discussed later, there has been no
need to add any cyclones.
The ESP inlet gas flow is 107,000 Nm^/hour. The flue gas
temperature is designed to be around 300 C (662 F) with a 350 C (662 F)
maximum. Because of the clogging economizer section of the boiler, there
have been many excursions well about 350 C (572 F). As a result, there has
been some corrosion at the top and front end of the ESP. Volund estimates
the inlet loading to be 7.5 g/Nm3.
Each of the two fields is 8.5 m (28 ft) high, and 7.0 m (23 ft)
deep. Flow-model studies were not conducted before installation. The
average flow velocity is 0.86 m/sec (0.26ft/sec). The maximum is 1 m/sec
(3.3 ft/sec). Each ESP field has two rectifiers. Volund would permit a
one-field ESP only on a small system where the regulations are not as
stringent.
Again it is helpful to quote from the Interersentskab brochure:
"In the electrostatic filter the speed of the smoke is
reduced to approximately 1 m/s, after which the smoke passes
between vertically suspended, electrically earth connected
profiled steel sheets. The mutual distance between the sheets is
about 25 cm (10 inches). Tightly stretched between the sheets
are a great number of steel wires, equipped with spikes. The
steel wires are insulated when hung and are connected with an
80,000 volt direct current generator. When the smoke slowly
passes this system of negatively charged steel wires, the dust
particles carried along will be electrically charged and will
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therefore be pulled over onto the earth-connected (grounded)
sheets. Thus, a continuous layer of dust will gradually be
formed on the sheets and can be shaken off by hard blows on the
sheets. This causes the lumps of dust to drop into accumulation
funnels. The flyash at Amager falls into a water bath and is
transported to a rubber belt conveyor by a screw conveyor.
The total efficiency of the electrostatic filter is more
than 98 percent. During 1972, approximately 5,000 tons of fly
ash was separated through Amagerforbraending's filters."
Even though the ESP is housed inside the normally warm
furnace/boiler room, the ESP hoppers are equipped with electric heaters.
When the room temperature falls to 10 C (50 F), the heaters are turned on
to prevent possible dew-point corrosion in the ESP.
Fly ash is removed from the bottom of the ESP hoppers
pneumatically. The pneumatic tube dumps onto a conveyor belt for transport
to the ash bunker to be humidified.
During the plant tour, a "gray smoke indicator" registered
o
values between 6.5 and 8.0 on the Ringleman scale. The 0 meter was not working.
Upon startup, the unit exceeded the 150 mg/Nm3 limit for
particulates. The primary reason was that a standard ESP (without special
entrance vanes) was used to clean a very highly loaded flue gas. The
Amager estimate of 7.5 g/Nm3 compares with more typical inlet loadings of
around 5 g/Nm3. This 2.5 g/Nm3 difference is attributed mostly to use of
the rotary kiln compared to a grate only system.
Because of noncompliance, Rothemuhle complied with its
guarantee. They then did conduct flow model tests. Turning and guide
vanes were added. The tests proved so successful that they again concluded
that cyclones would not have to be added.
The new Danish air pollution regulations specify limits for
particulates, HC1, and S02 (corrected to 11 percent 02 and 7 percent C0?).
Amager tests show that the unit is now well within the limits.
Danish Law Amager Plant
Particulates (mg/Nm3) 150 60- 90
HC1 (mg/Nm3) 1,500 700-900
S02 and S03 (mg/Nm3) 1,500 200-300
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Because the HC1 and S02 gases are in compliance, no scrubber has
been needed. A new feature of the law is that particulate tests are to be
made every month. The sampling point is 50 m up the 150 m chimney. The
respected Danish Boiler Testing Company is employed to perform the tests.
One emissions analysis reported is as follows:
Nitrogen (N2) 66.40$
Oxygen (02) 12.40*
Carbon Dioxide (C02) 12.MO$
Water (H20) 8.64$
Hydrogen Chloride (HC1) 0.06%
Sulfur Dioxide (S02) 0.01$
Unidentified and Measuring Errors 0.09%
TOTAL 100.00%
(Nitrogen is normally 78 or 79 percent on a dry gas basis (no
H20). But even dropping the H20 out, the N2 is still not near
78 percent. This analysis appears in the attractive brochure
Amager-forbraending Interessentskab. The Volund system does not
produce much NOX relatively due to the lower combustion
temperatures.
Officials repeated a statement heard elsewhere in Europe
and America that, "for each 1 percent above 96 percent efficiency, the ESP
purchase price doubles". This, of course, is far from accurate. However,
it makes the clear point that going from clean air emissions to very clean
air emissions is very expensive.
Water Pollution
Amager discharges a small amount of waste water directly into
the canal.
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ASH HANDLING AND DISPOSAL
Unfortunately, the new handling system at Amager caused
considerable problems. West designed differently and operates much
better. Basically, Amager uses a sluice, pusher and conveyors (see
Figure 14-33) while West uses a skip hoist (see Figure 14-34).
Because of the high temperature on clinkers at furnace outlet
(rotary kiln outlet) an ash pusher alone cannot do the perfect job as the
necessary air tighteners would be lost when it is not possible to maintain
an ash column on the chute.
If the ashes can be held in the chute and thus create
air-tighteners between the atmosphere and the vacuum inside the furnace as
it is the case in small furnaces without rotary kiln, the ash pusher alone
is the ideal solution on servicew and economy.
But the accumulation of ashes of 800°C will result in a condense
mass of clinker impossible to discharge.
To avoid the problem a sluice is included in the system
maintaining airtightness and in the same chute a water spray cooling is
included.
Originally the Amager rubber conveyors (Figure 14-35a) let too
much water and fine ash out and into the tank bottom. The material would
settle, build up, and then interfere with the conveying. There was
excessive wear on rollers and nylon bearings. Downtime for repair and
fines removal was excessive.
To partially solve the problem, stainless steel apron conveyors
were replaced by vibrating conveyors. They have also installed air pipes
in the bottom of the fines tank to keep the siftings in solution so they
can be removed.
Another major difference is that Amager uses about 3 tonnes of
water per tonne of ash while West uses only 1 tonne of water per tonnne of
ash.
Ash disposal at Amager is entirely different from the treatment
at West. The ash is simply trucked (Figure 14-35b) to reclaim further
portions of Amager Island. It is very profitable in that 1 m^ (1 yd^) of
land reclaimed from the sea is worth 200 to 300 D.kr. ($35 to 52). About 3
m3 (4 yd3) volume of ash is used to reclaim a 1 m^ (1 yd^) area.
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FIGURE 14-35a. RUBBER ASH CONVEYOR AT
COPENHAGEN: AMAGER
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FIGURE 14-35b. FERROUS SEPARATION FROM ASH AT
COPENHAGEN: AMAGER
-------
95
CHIMNEY
The chimney was constructed by a local contractor, Ramboll
Hannemann, using a Polish patented system for continuously pouring
concrete. The stack has a 2.8 m (9.2 ft) diameter. Most of the stack is
lined with 280 mm (11 inch) thick plain carbon steel. The flue gas
velocity is 27 m (89 ft/sec). At the top 10 m (33 ft), there is a corten
steel that is used to prevent corrosion. The stack height is 150 m (500
ft).
-------
96
PERSONNEL AND MANAGEMENT
Personnel
Amager's personnel structure is based on five shifts: early
mornings, days, nights, weekends, and replacements. Each shift has four
key men--the supervisor, boiler tender, furnace tender, and crane
operatorfor a total of 20 operating men.
Another 23 men are utilized in maintenance, repairs, and
cleaning. Two men are used at the scale house and two are used on the
tipping floor.
The administration personnel number six people: the director,
operating manager, office manager, two office employees, and a canteen
lady.
Realizing that the plant runs 2U hours per day, 365 days per
year, many of the above personnel are used as vacation, holiday, and sick
replacements. Considering this, the total plant staff numbers 53
employees.
Management
The Amager operations are managed by representatives from the
five communes listed in Figure 14-36. Note that 18 people attend the
annual general meeting (community stockholders meeting).
More frequent meetings are held with the management committee of
six representatives: a chairman, and the borgomiester from each commune.
Finally, the day-to-day administrative director is the focal
point for the communities with the plant personnel.
-------
97
1975-76
COMMUNES
Drag0r kommune
Frederiksberg kommune
Hvidovre kommune
K0benhavns kommune
Tarnby kommune
REPRESENTATIVES TO THE ANNUAL COMMUNITY SHAREHOLDERS MEETING
Borgmester Alb. Svendsen
Viceborgmester Chr. Lauritz-Jensen
Landsformand Arne Ginge
Borgmester Svend Aagesen
Kommunalbestyrelsesmedlem Jens Kristensen
Kommunalbestyrelsesmedlem Alf Christensen
Borgerrepraesentant Gunnar Ulbaek
Borgmester Lilly Helveg Petersen
Borgmester A. Wassard
Forretningsf0rer Andreas E. Hansen
Overborgmester Egon Weidekamp
Overlaerer Kit Falbe Hansen
Skoleinspekt0r Niels J0rn HougSrd
Typograf Kurt Kristensen
Havnemester Elhardt Madsen
Borgmester Tork. Feldvoss
Generalaudit0r Jens Harp0th
Journalist Marcelino Jensen
MANAGEMENT COMMITTEE
Borgerrepraesentant Gunnar Ulbaek (formand)
Borgmester Lilly Helveg Petersen
Viceborgmester Chr. Lauritz-Jensen
Borgmester Tork. Feldvoss
Borgmester Svend Aagesen
Borgmester Alb. Svendsen
ADMINISTRATIVE DIRECTOR
Willy Brauer (administrerende direkt0r)
FIGURE 14-36. MANAGEMENT STRUCTURE OF COPENHAGEN: AMACER
-------
98
ECONOMICS
Capital Cost (Assets and Liabilities)
The 1975-1976 annual report presents an accounting schedule of
assets and a schedule of liabilities. These are shown in Tables 14-3.The
refuse-fired hot water generating plant itself cost 117,600,000 D.kr.
($16,650,000) during the 1970-1972 construction period. The original
capital costs were as follows:
Ground Work and Construction 63.0 million Dkr
Machinery 45.0 million Dkr
Other Costs 9.6 million Dkr
TOTAL 117.6 million Dkr
Since then, another 40 million D.kr. has been spent on capital
improvements. Both assets and liabillities, by definition, equal
181,452,000 D.kr.
Annual Costs (Expenses and Revenues)
Annual costs and revenues are distributed as shown in Table
14-5. On the revenue side, note that the tipping fees ($6.06/t) and the
general head tax ($11.33/t) provide most of the revenue totaling $17.39
per ton. Charging a tipping fee of only $6.06/ton encourages suburbs,
private haulers and industries to contribute waste. If they had to
support the entire $17-39 per ton, many who have freedom of choice
regarding disposal, might apt for landfilling at a distant site. Having
the foreing waste and its tipping fee will help carry some of the fixed
expenses. The revenue from district heating, originally planned to be
2,200,000 D.kr. in this year, actually turned out to be more than double
that at 4,878,000 D.kr. By definition of a "not-for-profit organization",
the expenses must equal revenues. In this case, they are both equal to
36,305,000 D.Kr. ($6,272,460).
Table 14-7 presents the annual costs and revenues per tonne for
almost 5 fiscal years. Note that increased revenues from the sale of heat
-------
99
TABLE 14-3. ASSETS (MARCH 31, 1976) AT COPENHAGEN:AMAGER
Current Assets (Cash, Stocks, Supplies) 12,882,000 Dkr
Money on Loan to Others 2,431,000
Transfer Station 8,980,000
Landfill 1,625,000
Refuse Burning Hot Water Generator* 155,534,000
Under Surplus, 1972-1973 4,339,000
Over Surplus, 1973-1974 1,757,000
Over Surplus, 1974-1975 489,000
Over Surplus, 1975-1976 2,093,000 4,339,000
TOTAL ASSETS 181,452,000 Dkr
* Includes 7 years of improvements.
-------
100
TABLE 14.4. LIABILITIES (MARCH 31, 1976) AT COPENHAGEN:AMAGER
Loan on "Refuse Fired Hot Water Generator 101,920,000 D.kr.
Loan on Landfill 108,000
Short Term Creditors 2,538,000
Accrual Account for Test and Development with
Waste Treatment 60,000
Accrual Account for Finalization of Building Surroundings
and Machinery Works 35,000
Accrual Account for Renewal of Ash Transportation
Plant (?) 1,566,000
Accrual Account for Interest and Capital Return 321,927,000
Equity in the Refuse Burning Plant 39,718,000
Equity in the Transfer Station 580,000
TOTAL LIABILITIES 181,452,000 D.kr.
-------
101
TABLE 14-5. ANNUAL COSTS DURING 1975-1976 AT COPENHAGENrAMAGER
Operational Salaries 5,028,000 Dkr
Other Operation Expenses 2,196,000
Ash Disposal Expenses 769,000
Transfer Station Expenses 4,008,000
Landfill Operation Expenses 853,000
Administrative Expenses, Meetings 197,000
Administrative Salaries 514,000
Other Administrative Expenses 224,000
Plant Maintenance 2,415,000
Government Taxes and Other Fees 1,018,000
Interest on Loan 7,425,000
Depreciation on Plant 8,000,OOP
TOTAL EXPENSES 32,647,000 Dkr
Account Set Aside to Build an Ash Transportation 1,566,000*
Plant
Surplus Returned to Asset Account 2,093,000
GRAND TOTAL 36,305,000
Amount set aside for changing (1) existing ash discharge plant with
new (1977) ash transport plant (2) existing rubber belts with vibrating
conveyors (3) magnetic separation and (4) ash treatment prior to selling.
-------
102
TABLE 14-6. REVENUES DURING 1975-1976 AT COPENHAGEN:AMAGER
Communities' Tipping Fee at 40 Dkr/tonne ($6.06/ton)
*
Government (?) Tipping Fee at 40 Dkr/tonne
Private Haulers' Tipping Fee at 40 Dkr/tonne
*
Head Tax at 30 Dkr/year ($4.55/year)
Revenue From Energy Sale to District Heating Network
Transfer Station Tipping Fee (?)
Landfill Tipping Fee
Interest Earned on Current Assets
Rent of Excess Office and Filing Space
TOTAL REVENUES
7,872,000 Dkr
169,000
2,423,000
16,441,000
4,878,000
2,743,000
515,000
1,019,000
246,000
36,306,000 Dkr
Net Disposal Fee
= tipping fees + head tax
= $6.06 + $4.55
ton person year
= $6.06/T + $11.33/T
= $17.39 per ton
( 1 year)(l day person) (2000 Ibs)
(365 days)( 2.2 pounds) ( 1 ton )
Assumes 6.00 D.Kr. per U.S. $ in 1975-76
-------
103
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have offset increases in operating costs so that the net cost to the
taxpayer has remained relatively steady for 5 years.
Profitableness at Exploitation of Heat
For the final time, Mr. Blach's comments are entered into the
American record.
He presents the analytical logic one would expect supporting
"economy of scale theory". We, however, have learned that in actual
practice there is little economy of scale. Designers and customers of
large plants tend to mitigate the potential economies by extra "bells and
whistles" which would not be considered in the small plant.
This presents the economics of a 3 x 12 t/hr plant versus a 3 x
3 t/hr plant. The analysis uses three different Kcal/kg estimates and two
utilization rates.
"As mentioned before, the cost of the installation of a
boiler for the recovery of the waste heat can be expected to be
of the same magnitude as the cost of other forms of installation
for the cooling of the flue gas. In the same way, the
operational and maintenance costs can be calculated to be of the
same magnitude provided the boiler construction is executed
correctly and appropriately, taking into consideration the
special corrosive, wearing, and clogging properties of the flue
gas.
As previously mentioned, the income from the waste heat
sales will be a real operational income which can cover a larger
or smaller part of the operational costs, depending on how large
an amount of the produced heat can be sold and at which price.
The following enclosed two tables (Tables 1M-8 and 1^-9) show
examples of operational costs (exclusive of interest and
depreciation) and incomes resulting from heat sales from a large
plant with three units of 12 t/h and a smaller plant with three
units of 3 t/h. Figures are calculated for net calorific
values of 1,500, 2,000, and 2,500 Kcal/kg. Plant utilization
for the smaller plant is 50 percent and 75 percent,
respectively, and for the larger plant 65 percent and 80
-------
105
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107
percent, respectively, of the nominal capacity. As a total sale
of the produced heat all the year round cannot normally be
expected, there has only been calculated the incomes driving
from sales of 75 percent of the produced heat.
The obtainable selling price for the heathere rated to
Dkr. 20, -per million Realwill be determined by the fact that
it should be able to compete with the production price for a
normal oil-fired plant, i.e., among other things, it will be
dependent on the price of oil. When in competition with heat
from power stations, the selling price is lower (Dkr.
12,--15,--per million Kcal).*
As shown on the tables, the incineration capacity (Line 1)
and operational costs (Line 6) are equally rated for the
different calorific values. This, of course, is an
approximation, but nevertheless close to the real figures as far
as the operational costs are concerned, which will increase only
little with the increase of the calorific value, whereas the
incineration capacity may vary with the calorific value,
depending on the refuse composition, so that the capacity can
normally be expected to increase for lower calorific powers.
This means that the values for the operational costs per ton
refuse incinerated can be expected to be proportionately lower
for the refuse with the lower calorific value than for the
refuse with the high calorific value.
As regards the small plant, there has been calculated with
two-shift operation at 50 percent exploitation and three-shift
operation at 75 percent exploitation, and the plant closed on
Saturdays and Sundays. For the larger plant, calculations are
based on continuous operation all days of the year.
It can be seen that the operational costs per burnt ton of
refuse are much cheaper for the large plant than for the smaller
one. The operational costs for the small plant executed as grate
furnace and with mechanical gas cleaning, and for the large
plant executed as grate/rotary kiln furnace with electrostatic
precipitator, will be almost equal per ton of plant capacity.
With uniformly rated interest and depreciation conditions, the
* The selling price of 12-50 D.Kr./million Kcal is an old price used in
1975-1976. Prices today (1978) are 30-60 D.Kr./Gcal ($1.35-$2.70 per
million Btus).
-------
108
large plant will consequently also have the lower total
operational costs per treated ton of refuse.
Accordingly, with the large plant, a more effective and
secure refuse treatment, a better gas cleaning, as well as a
cheaper treatment price are achieved."
-------
109
FINANCE
The financial arrangements were straightforward. The 5
municipalities put in money based on population. The remainder was
borrowed at local banks. The payoff period is variable as well as the
interest rate that has averaged about 8 percent.
-------
110
REFERENCES
(1) Amager-forbraending Interersentskab (Amager-refuse incinerator for
the public welfare). A colorful public relations description of the
plant from all aspects.
(2) I/S Amager-forbraending. The 1975-1976 Annual Report of plant
financial results.
(3) Volund patents supplied by Volund. Dated from 1931 to 1975.
(4) Maximum Rated Capacity (MRC) on Volund Rotary Kiln Furnaces by
Gabriel Silva Pinto, Project Manager. VIG (The Volund Incinerator
Group) News, pp 3-4.
(5) Miscellaneous Collection Routing Data Processing Materials from P.
Nielsen of Renholdnings Selskabet, the local not-for-profit
collection society.
(6) Data sheet about Volund, 3 pages.
(7) Affaldsbehandling (Refuse Treatment-Volume Reduction by Different
Treatment Methods), a Volund publication.
(8) Statistical Data Sheet on the Amager Plant, 23 form pages with
relevant data recorded.
(9) Plants for Incineration of Refuse by Chief Engineer (former), Cand.
Polyt. E. Blach, A/S Volund. An excellent 25-page technical paper
telling how Volund and its competitors build refractory, water
wall, and rotary kiln furnaces for refuse distraction and energy
production.
1828L
>US SOWWWI.TWIITIWiOFf.Ce.19W -620-007/6311
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