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H. Lanier
Hickman Jr.
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Part
9a: The Awakening of Waste-to-Energy in the US
Links
to other parts of our series may be found at the end
of this article.
This article
is a continuation of the History series. Part 9 discusses
the emergence of waste-to-energy (WTE) as part of integrated
solid waste management in the United States. It is divided
into two parts: Part 9a looks at the early part of 1950-2000,
and Part 9b looks at the latter half of this period
that was the golden expansion years of WTE and the failure
of its continued growth. A book is planned on the History
series published in MSW Management, and in that
book an expanded discussion of the subject of WTE will
be provided. The author apologizes for any omissions
that might have occurred in these two short articles.
Burning solid
waste under controlled conditions (incineration) is
not a modern idea. Recovering the energy released from
burning waste materials is not a new idea either. In
the 1700s waste paper was used for heating and cooking
(Phillips, 1998). Used vegetable oils were used in lamps
in the 1700s. In 1876, the English burned, in a unit
they called a "crematory," solid waste for
fuel to generate steam to produce electrical power.
There are reports of the successful use of refuse-derived
fuel (RDF) in Japan around 1897 (Phillips, 1998). Burning
solid waste as a disposal method came to the US soon
after the English experience noted above.
The Early
US Years
Apparently,
the US Army built the first solid waste incinerator
in the US on Governor’s Island in New York Harbor
in 1885. In the same year, the City of Allegheny, PA,
built the first local government-owned incinerator.
Other US cities quickly followed Allegheny’s lead.
US incinerator designs drew heavily from European technology,
but US experiences were not overly successful primarily
because of the higher moisture content of US refuse
(see Note 1). In the early 1900s, as the US experienced
its first real surge of urban growth, the incinerator
was a popular choice in many cities. A major cause for
the expansion of incineration was close-in disposal
sites being displaced as cites grew (sound familiar?).
This resulted in longer hauling distances to more distant
sites. With a lack of transfer technology and noncompacting
collection vehicles, long-distance hauling was not practical;
another method was needed. Incineration filled that
need.
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| Figure
1. Batch-Type Incinerator Design |
The use of
incineration in the US grew during the early decades
of the 20th century until, by the end of
the 1930s, there were more than 700 units. US incinerator
designs used either traveling grates or batch-fed, hand-stoked
furnaces (APWA, 1961) (see Figures 1 and 2). These figures
provide a good comparison between the two furnace designs
and the gradual sophistication that was occurring in
incineration in the US.
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| Figure
2. Traveling Gate Incinerator Design |
US incinerators
with refractory lined walls, the most common early design,
experienced a number of major operational problems.
The most prevalent problems included poor combustion,
major air emissions, incomplete burnout, and major slagging
of glass from containers in the solid waste. A lack
of knowledge and experience in the combustion of solid
waste can be attributed as a major cause for these problems.
Incinerators were designed by engineers with little
or no understanding of the principles of combustion
(the "3 Ts": time, temperature, and turbulence),
appropriate materials for furnaces, or methods to control
emissions (Phillips, 1998).
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| Figure
3. Traveling Grate |
Clankers
and Clinkers
The early
1960s US Public Health Service (USPHS) solid waste program
began to study the problems with incineration as a means
of disposal. At that time, many major US cities depended
on what can best be described as antiquated, poorly
designed, and poorly operated incinerators to manage
a major portion of their solid wastes.
With some
help from the USPHS, the incinerator industry began
to develop new concepts in design, materials, and operation.
New designs included the installation of scales to help
monitor and control the through feed of the facility.
Tipping floors and pits designed to handle the design
loads of facilities also improved. A minimum of three
days’ supply of solid waste was considered necessary
when sizing storage pits. Hoppers were designed to meter
an even flow of solid waste into furnaces and to provide
a seal at the charging end of the unit. Bridge cranes
became the main means for charging furnace hoppers.
Terminology became more standard with defined terms
for an incinerator (the entire plant), furnace (where
most of the burning took place), combustion chamber
(where secondary combustion of the airborne particles
took place), and subsidence chamber (where particulates
are allowed to settle).
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|
Water-spray fly-ash collector |
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| Ash
hoppers |
Specially
designed refractory materials also began to be used,
thereby reducing slagging problems. The principle of
the "3 Ts" began to be applied to design and
operations, thereby resulting in improved burnout of
solid waste and more complete combustion of the exit
gases. The need for control of particulate matter in
the exit gases also became much more common. Wet scrubbers
in a variety of designs were installed to remove fly
ash from the exit gases (photo 1 is an illustration
of a baffle water-spray fly-ash collector). Inclined
traveling grates and inclined rotary kilns became the
dominant designs for furnaces. Landfilling was the most
common method of ash disposal.
Even in the
early designs, combined ash (fly and bottom) was the
most common design for ash handling. Photo 2 shows ash
hoppers located beneath the discharge chambers of the
incinerator furnaces.
1970
In 1970,
the Resource Recovery Act (RRA) amended the organic
federal solid waste legislation (the Solid Waste Disposal
Act) and charted a much broader solid waste role for
the federal government. New authorities and resources
were provided to assist in the development of new and
improved systems and technologies for the management
of solid waste. RRA, under Section 208, authorized "demonstration
grants" to demonstrate new and improved technologies.
RRA also defined resource recovery as the recovery of
both materials and energy recovery from MSW. New programs
in both areas were initiated. When USEPA was formed,
the Bureau of Solid Waste Management (BSWM), still part
of the USPHS, was transferred to this new agency.
The pressures
of the Clean Air Act, coupled with the emergence of
sanitary landfills, led to many of the old incinerators
being closed. RRA gave the federal solid waste program
the opportunity to address WTE with increased dollars
and human resources and to expand the efforts begun
during the period from 1965 to 1970. A variety of studies
by the technical services group, under the direction
of Lanny Hickman of operating performances and emissions
(air and ash), were an important background to the expanding
research, development, and demonstration program (see
Note 2). The research group of BSWM, under the leadership
of Andy Breidenbach, launched a comprehensive effort
to define the good, the bad, and the ugly about MSW
incineration. This work contributed significantly to
the emergence of MSW incineration during the 1980s-’90s.
(Alter, 1987). Journeys were made to Europe to analyze
European incinerator technology and to determine if
technology transfer was feasible.
MSW incineration
technologies in the US beginning in 1965 concentrated
on the use of solid waste as an energy source. This
evolution followed two paths:
- Mass
Burn. The combustion of solid waste as a fuel
in its as-discarded form
- RDF.
The processing of solid waste into coarse or finer
particles with or without separation of noncombustible
materials present in the solid waste
In time,
through the ASTM Committee E-38, Resource Recovery,
solid waste as a fuel was defined into seven RDF categories,
with RDF-1 the fuel for mass-burn facilities and either
RDF-2 or RDF-3 as the most used forms for processed
solid waste. Densified RDF (d-RDF; RDF-5) was also considered
to ease storage and handling demands. When this MSW
Management series expands into a book, more time
can be spent on Committee E-38 and the designations
of solid wastes as a fuel.
Looking
for the Magic Black Box: RDF an American Idea?
The federal
solid waste program studied many new MSW combustion
concepts during the 1970-1980 time frame. Of particular
interest to the program were processes that would allow
for the recovery of both materials and energy. In addition,
the conversion of MSW to other energy forms was also
of interest. It is important to remember that while
many of the technology concepts studied failed, the
federal program was not a failure; indeed, demonstrating
that these technologies would not work prevented many
local governments from making fatal financial mistakes
by selecting white elephants to burn their solid waste.
The following
are brief descriptions of some of the more interesting
resource recovery projects that were supported in one
manner or the other by both the USPHS and EPA. The information
about these projects was drawn heavily from a paper
published in 1987 by Harvey Alter.
CPU
400. Began in 1968 with Combustion Power Company,
the purpose of this project was to use fluidized-bed
pyrolysis of RDF to generate a gas to run a turbine
generator. In 1972, RDF was produced, but problems in
firing the turbine as a result of particulate matter
in the RDF-produced gas that eroded the turbine blades.
Eventually the inability to clean the gas economically
resulted in terminating the project.
Garrett
Pyrolysis. Garrett Research & Development
Company received a BSWM grant to evaluate a flash pyrolysis
technique. The process was to convert RDF to a liquid
fuel for energy recovery in a 200-tpd plant built in
El Cajon, CA. The ability to prepare RDF capable of
pyrolyzing into a liquid fuel was never achieved, but
processing and separation of glass, aluminum, and magnetic
metals were successfully demonstrated.
Black
Clawson. This project used a hydropulping technology
(Black Clawson) utilized in the paper industry to convert
MSW into a wet RDF capable of burning sludge in a fluidized-bed
combustor. Efforts also tried to use the hydropulped
product as feedstock for paper or paperboard. The quality
of the product was such that this never occurred. Alter
notes that the RDF technology was a frontrunner for
plants built in Hempstead, NY, and Dade County, FL.
Landgard.
Landgard was a pyrolysis system developed by Monsanto.
RDF was processed in a rotary refractory lined pyrolysis
kiln to produce a gas that was then fired in a chamber
with downstream heat recovery in a boiler. BSWM funded
the evaluation of a 1,000-tpd plant in Baltimore, MD.
Major materials handling problems, difficulty with the
rotary kiln pyrolysis unit, and air pollution control
ultimately led to project shutdown. Dave Sussman, EPA
project officer, noted that several valuable lessons
were learned, however, including a better understanding
of the problems of handling RDF and the need for clean
RDF to minimize corrosion and erosion of downstream
equipment.
St.
Louis—Union Electric. This project,
directed at co-firing of RDF with coal, had (perhaps)
a greater influence on the development of WTE in the
US than any of the other projects listed here. Its impacts
were both positive and negative: positive from the standpoint
that it demonstrated the capability of co-firing; negative
because of conclusions drawn that that air classification
alone would remove noncombustibles–a fact proven
to be wrong in future RDF facilities.
Misinterpretation
of data and research results in many RDF studies led
to the adoption of a system design that failed to produce
a clean RDF. Consequently, excessive corrosion and erosion
of equipment downstream from the RDF preparation equipment
led to the failure of a number of RDF facilities. Plants
built based on the work at St. Louis included Milwaukee,
WI; Ames, IA; Monroe County, NY; Connecticut; Hawaii;
Michigan; and Florida, to name a number of locations.
Milwaukee could not meet its RDF specifications and
closed. Ames was successful after certain changes in
the process and operated for 20 years. Monroe County
closed as a result of the inability of their processing
lines to develop a clean RDF.
RDF is now
a successful technology in a number of locations where
dedicated boilers were selected rather than attempting
to co-fire with other fuels. Currently there are 26
RDF plants working in the US processing some 27,000
tpd of RDF (Kiser & Zannes, 2000). Figure 4 is an
illustration of a typical RDF process line that emerged
from the many efforts in RDF development.
The next
issue will continue with the last half of Part 9.
Notes
1. It is
a common practice to believe that a technology that
works on one MSW stream will naturally work on another
MSW stream in another geographic location. Such is not
the case country to country or even state to state or
city to city. While the inherent characteristics of
MSW do remain consistent location-to-location, the mix
of those characteristics varies dramatically. Moisture
is low in dry locations and high in coastal, subtropic,
and tropic areas. Glass is higher in Europe than it
is in North America. There are higher percentages of
organics in Asia than in North America. Aluminum containers
are higher in certain parts of the US than in others.
Hence, intelligent planning in MSW management and in
the selection and adaptation of someone else’s
technology should be based on careful analysis on the
MSW stream in question and the potential application
of a new or modified technology (Hickman, 1999).
2. During
this period of time, emission and ash tests were run
on a variety of plants, including Braintree, MA; the
four plants in the District of Columbia; Alexandria,
VA; Weber County, UT; Dekalb County, GA; Atlanta, GA;
Delaware County, PA; New Orleans, LA; a conical (teepee)
burner; and a trench construction and demolition waste
burner. From these studies, one summary report was prepared
("Evaluation of Seven Incinerators," USEPA,
Washington, DC, 1976), individual reports were issued
for all plants, and a testing manual was issued (Testing
Manual for Solid Waste Incinerators, USEPA, Washington,
DC, 1976).
References
Alter,
Harvey. The History of Refuse Derived Fuels.
Resources and Conservation. Elsevier Science Publishers,
Amsterdam, Netherlands. 1987.
APWA.
Municipal Refuse Disposal. American Public Works
Association, Chicago, IL. 1961.
Hickman
Jr., H. Lanier. Principles of Integrated Solid Waste
Management. American Academy of Environmental Engineers,
Annapolis, MD. 1999.
Kiser,
Jonathan V.L. and Maria Zannes. The IWSA Directory
of Waste-to-Energy Plants, Year 2000. Integrated
Waste Services Industry, Washington, DC. 2000.
Phillips,
J.A. Managing America’s Solid Waste. National
Renewable Energy Laboratory publication #NREL/SR-570-25033.
NREL, Golden, CO. 1998.
Taylor,
A. and M. Zannes. The 1996 IWSA Municipal Waste Directory
of United States Facilities. Integrated Waste Services
Association, Washington, DC. 1996.
H. Lanier
Hickman Jr., P.E., D.E.E., is a member of MSW Management’s
Editorial Advisory Board.
To
read the other parts in this feature please click on
the relevant links below:
Part
1: Introducing the Pioneers
Part
2: Of Mosquitoes, Flies, Rats, Swine, and Smoke
Part
3: The Sanitary Landfill
Part
4: Building a National Movement
Part
5a: Building an Infrastructure
Part
5b: Building an Infrastructure
Part
6: Collecting Solid Waste/No Longer Beasts of Burden
Part
7a: Landfill Gas Odors/Fires, Explosions, and Kilowatts
Part
7b: Landfill Gas - An Asset, Not a Liability
Part
8: Composting: Sometimes a Good Idea Does Not Sell
Part
9a: The
Awakening of Waste-to-Energy in the US
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