PROCEEDINGS FROM A
TECHNICAL CONFERENCE ON
WASTE-TO-ENERGY TECHNOLOGY UPDATE - 1980
(April 15 and 16, 1980)
by
G. Ray Smithson, Jr.
BATTELLE
Columbus Laboratories
505 King Avenue
Columbus, Ohio 43201

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EPA Report Number
September, 1980
Proceedings from a
TECHNICAL CONFERENCE ON
WASTE-TO-ENERGY TECHNOLOGY UPDATE - 1980
(April 15 and 16, 1980)
by
G. Ray Smithson, Jr.
BATTELLE
Columbus Laboratories
505 King Avenue
Columbus, Ohio 43201
Grant No. R806653010
Harry Freeman
Incineration Research Branch
Industrial Pollution Control Division
Cincinnati, Ohio 45268
INDUSTRIAL ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268

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DISCLAIMER
This report	has been reviewed by the Industrial Environmental Research
Laboratory-Cincinnati,	U.S. Environmental Protection Agency, and approved for
publication. Approval does not signify that the contents necessarily reflect
the views and policies	of the U.S. Environmental Protection Agency, nor does
mention of trade names	or commercial products constitute endorsement or recom-
mendation for use.
ii

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FOREWORD
This report contains the proceedings of a technical conference held
in April of 1980 to review the status of U.S. EPA's waste-to-energy research
programs. The information contained herein will be of interest to those in
the private and public sectors working to develop and utilize waste-to-energy
technology.
Requests for information on the topics discussed in the report should
be directed to the Incineration Research Branch, IERL-Ci or to the individual
authors.
David G. Stephan, Director
Industrial Environmental Research Laboratory
Cincinnati, Ohio
iii

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CONTENTS
Page
FORWORD	iii
INTRODUCTION 		1
CONFERENCE PROCEEDINGS 		4
Session I - Conversion Processes
Pilot Scale Pyrolytic Conversion of Mixed Wastes to Fuel ....	4
Chemical Reclamation of Scrap Tires 	 .....	14
The California Mobile Pyrolysis System 		32
Thermochemical Conversion of Biomass to Gasoline 		42
Energing Technology for Maximum Conversion
of Waste Cellulose to Ethanol Fuel		50
Atmospheric Fluidized Bed Combustion of
Municipal Solid Waste: Test Program Results 		52
Session 2 - Combustion
Evaluation of the Ames Solid Waste Recovery System 	 80
Test Firing Refuse Derived Fuel in an Industrial Boiler .... 88
Co-Firing Refuse Derived Fuel (Dross) in
A Stokered Boiler 	 100
Corrosion Inhibition in Refuse-to-Energy Systems 	 106
Co-Firing Densified Refuse-Derived Fuel
in A Spreader Stoker-Fired Boiler 	 112
Co-Firing Fluff RDF and Coal in A Cement Kiln	118
Steam Pyrolysis of Organic Wastes As A Source
of Chemicals and Industrial Feedstocks 	 138
Session 3 - Environmental Assessments and
Pollution Control Technology
Environmental Assessment of Waste-to-Energy
Conversion Systems			148
Emissions Assessment for Refuse-Derived Fuel Combustion ....	156
Combustion and Emission Assessment of Refuse-Derived
Fuel Cofired with Pulverized Coal	166
Pilot Scale Evaluation of Four Refuse-Derived Fuels 		176
Application of Slipstreamed Air Pollution Control
Devices on Waste-as-Fuel Processes 		194
Treatment of Wastewaters from Refuse-to-Energy Systems 		200
iv

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PROCEEDINGS FROM A
TECHNICAL CONFERENCE ON
WASTE-TO-ENERGY TECHNOLOGY UPDATE - 1980
(April 15 and 16, 1980
to
U.S. ENVIRONMENTAL PROTECTION AGENCY
INDUSTRIAL ENVIRONMENTAL RESEARCH LABORATORY
CINCINNATI, OHIO
from
BATTELLE
Columbus Laboratories
July 30, 1980
INTRODUCTION
The U.S. EPA is vitally interested in the dissemination of the
results of its research and development activities to inform potential users
and to encourage widespread utilization of the technology under development.
The Agency also is interested in the assessment of its research and in
acquiring extramural input to the planning of future research and development.
One of the more effective means to accomplish these goals is to sponsor
periodic technical conferences whose basic objective is to provide an update
of the status of technological developments in areas of interest. One such
area is the utilization of the energy contained in municipal and industrial
wastes for useful purposes.
The concept of recovering energy from wastes is not new but this
practice has not been adopted to any significant extent within the United
States. However, for several years there has been growing impetus in the
U.S.—both within the private sector and Federal, state, and local govern-
ments— to develop various techniques for recovering energy from the combustible

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fractions of solid wastes and for separating recyclable materials from wastes
generated by industries and large communities. Research efforts have been
expended on many technological approaches and several have been developed to
various stages of practice.
Acting upon the belief that a technical conference on the status
of waste-to-energy research activities would be beneficial and timely,
Battelle Columbus Laboratories proposed such a conference to U.S. EPA. The
purposes of the technical conference were:
•	To review the status of relevant research and
development activities being supported by U.S.
EPA's Industrial Environmental Research Labor-
atory (IERL-Ci) at Cincinnati, Ohio.
•	To consider the most effective means for the
commercial exploitation of the results of this
research.
•	To review areas for future research and to
recommend strategies for the implementation of
such research.
After Battelle's grant proposal was accepted by the U.S. EPA,
the specific objectives and mechanisms for conducting the technical conference
were developed jointly with a steering committee composed of representatives
of these two organizations. Following the adoption of the specific objec-
tives and mechanisms, this committee selected speakers and discussions leaders
from various organizations conducting R&D in waste-to-energy systems for
IERL-Ci. These individuals were invited to participate in the conference with
the understanding that the findings and recommendations would be made available
to persons and organizations interested in this area of technology. The final
agenda for the conference was as follows:
2

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Tuesday, April 15, 1980
Session 1 - Conversion Processes
Registration and Coffee - Foyer
Introduction
Welcome
Session Overview - Walter Liberick, U.S. EPA, IERL
Pyrolysis of Mixed Waste to Fuel - Herbert Kosstrin, Energy Resources Co., Inc.
Pyrolysis of Industrial Waste - George Frazier, University of Tennessee
Portable Unit for Pyrolysis of Agricultural & Forestry Wastes -
Herbert Kosstrin, Energy Resources Co., Inc.
Coffee Break
Bench Scale Pyrolysis to Polymer Gasoline - Jim Biebold, Solar Energy
Research Institute
Bio-Conversion-Acid Hydrolysis - Charles Rogers, U.S. EPA, MERL
Fluidized Bed Combustion of Solid Waste - Lyn Preuit, Combustion Power Co.
Luncheon
Guest Speaker - Dr. Eugene Moulin, University of Dayton
"Stress is Contagious"
Session 2 - Combustion
Session Overview - Bob Olexsey, U.S. EPA, IERL
Evaluation of Ames Energy Recovery System - A1 Joensen, Iowa State University
Firing of Solid Waste in an Industrial Boiler - Gary Boley, City of
Madison, Wisconsin
Cofiring Refuse Derived Fuel (RDF) Dross in a Stoker Boiler -
Fred R. Rehm, Department of Public Works, Milwaukee, Wisconsin
Effects of Using Solid Waste as a Supplementary Fuel - H. H. Krause,
Battelle Columbus Division
Coffee Break
Cofiring Densified Refuse Derived Fuel in A Spreader Stoker Fired Boiler -
Ned Kleinhenz, Systems Technology Corp.
Cofiring of Solid Waste in a Cement Kiln - Cliff Willey, State of Maryland
Pyrolysis of Agricultural Wastes in a Steam Atmosphere - Michael Antel,
Princeton University
Wednesday, April 16, 1980
Session 3 - Environmental Assessments and Pollution Control Technology
Session Overview - Harry Freeman, U.S. EPA, IERL
Environmental Assessment of Waste-to-Energy Processes - K. P. Ananth,
Midwest Research Institute
Emission Assessment from RDF/Hazardous Waste Combustion - Fluidized Bed -
Jim Chrostowski, Energy Resources Co., Inc.
Emission Assessment from RDF/Hazardous Waste Combustion - Stoker Fired -
John Allen, Battelle Columbus Division
Coffee Break
Emission Assessment from RDF/Hazardous Waste Combustion - Suspension Firing -
Robert Pease, KVB, Inc.
3

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Cofiring of four RDF's in a Pilot Scale Facility - Richard Brown, Acurex, Inc.
Air Pollution Control for Waste as Fuel Processes - Fred Hall, PEDCo
Environmental, Inc.
Water Pollution Control for Waste as Fuel Processes - Gordon Treweek,
James M. Montgomery, Inc.
Luncheon
The conference was held in Cincinnati, Ohio. The proceedings of the
conference are included in this report.
3a

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PILOT SCALE PYROLYTIC CONVERSION
OF MIXlED WASTES TO FUEL
by H.M. Kosstrin, Ph.D.
Introduct ion
One of the more promising techniques for reclaiming
energy from municipal solid waste is through pyrolysis,
which is the destructive distillation of waste materials
thereby converting them to clean fuels such as low-Btu gas,
residual oil, and char.
EPA has been involved in the development and demonstra-
tion of several different pyrolysis technologies such as the
Landguard system based upon a rotary kiln, the Tech-air
concept based upon a fixed bed pyrolyzer, and "Flash Pyrolysis"
based upon an entrained bed heated with recirculating hot
char. While all of these technologies are based upon
pyrolysis, all of them produce different energy by-products
because of the different reactor characteristics and oper-
ating parameters inherent in each one.
The objectives of the work being carried out by Energy
Resources Co. are to explore the kinetics of pyrolysis of
municipal waste and agricultural wastes and to develop a
data base on pyrolysis that will allow design engineers to
select pyrolysis system operating conditions for commercially
available systems that will provide the desired mix of
product yields given the mixture of wastes available in a
given geographical area. Because the results of the data-
taking efforts will be extrapolated to full-scale systems,
it is necessary for the experimental work to be carried out
on a pilot plant scale.
The work performed included a literature survey of
pyrolysis to determine the properties of various wastes and
the reactor operating variables which would have a signifi-
cant influence on the project. With these data in hand, a
fluidized-bed pilot plant was constructed to carry out the
collection of kinetic data. The data analysis included
product characterization of the char, oil and gas along with
the development of a prediction model for the oil. The
various parameters that were varied are listed in Table 1.
The result of the data base compiled is to assist the
design engineer to understand the important trends in
pyrolyzed design.

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TABLE 1
PARAMETERS VARIED
Reactor Temperature
Fluidization Velocity
Feed Rate of Waste
Bed Height
Feed Particle Size

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Pyrolyzation of Wastes
The data obtained concern the conversion of a wide
range of wastes to fuels in a fluidized-bed pyrolysis
system. The materials pyrolyzed in both Phase I and Phase
II of the test program are shown in Table 2. The variables
studied as to their effect on the final products of pyrolysis
were temperature, fluidization velocity, feed rate of
pyrolyzable material, bed height (static), and particle
size.
Various experimental conditions other than pyrolysis
were run as a means of determining the usefulness of the
system. These included steam gasification (pyrolysis),
partial oxidation, combustion, and steam partial oxidation
runs.
The major conclusion that comes out of this work is
the importance of secondary reactions in determining the
final product mix of the various waste materials. Pyrolysis
occurs in two steps as described in the modeling section of
this report.
1.	Primary decomposition--devolatilizes the feed into
its light fractions, oil and gas, and leaves a
residue generally considered a char. The quality
of the char depends upon the temperature of pyrolysis
of the char formation. The char contains the
inerts from the feed, generally considered ash.
2.	Secondary decomposition—these secondary reactions,
which predominate above a critical temperature,
devolatilize the oil produced via the primary
reactions into a gas and a residue. This residue
is additional char.
From work performed during Phase I of the project, an
analytical expression for the yield of pyrolytic oil and
gas, taking into consideration both primary and secondary
reactions, is derived in the modeling section of this
report. The data obtained confirm the analytical expression.
Figure 1, the yield of pyrolytic oil for sawdust, shows
the general shape of the oil yield curve. The secondary
reactions begin to dominate after 400" C. At temperatures
above 400* C the yield of pyrolytic oil decreases and the
corresponding yield of gas increases because of these secondary
reactions. The development of an analytical expression for
the formation of gas from both primary and secondary
reactions has been accomplished. The analytical expressions
are shown in Tables 3 and 4.
6

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MATERIAL: SAWDUST (SAW)
1.5
uj
a.
u»
O
|
a
-j
UJ
>
-J.
o
».3
1-2
1.1
o cP
	o

THWPSPATUflS IOSGSSBS Ci
Figure 1. Model curve for pyrolysis oil yieid data of sawdusx.
7

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TABLE 2
MATERIALS PYROLYZED
INDIVIDUAL
Phase I
Phase II
Paper
Sawdust
Corncobs
Waste Oil
Municipal Solid Waste
Sludge
Tires
Plastics
Wood Chips
Pyrolytic Oil
Wheat Straw
Rice Straw
Cotton Gin Waste
Pine Bark
Industrial
Char (from
Sewage Sludge
pyrolysis of
sawdust)
Coal
MIXTURES
Paper + Sawdust
Corncobs + Manure
Paper + Plastics
Coal + Sawdust
Coal + Sludge + Munic-
ipal Solid Waste
Coal + Municipal Solid
Waste
8

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TABLE 3
ANALYTICAL EXPRESSION ?OR THEORETICAL GAS YIELD
vqas = 1-C-^Sil t1 " oil (I"3)! 'gas
vSil oil * * ' °
wnere
C = measured char yield, as provided by the data, mass
fraction of refuse fed.
= ultimate oil yield, from oil yield correlation,
mass fraction of refuse fed.
1 - e-K't'
3 1 - 	
k 111
Jc' = ko e-E'/ST
t' = a
/ vA
•oU = ! - 1 *	'S x e"koUl=s-tf)
*oil S
koil 3 (*o)oil e"soil/RT
Ts = sampling time, provided from data
ts-t^ = lag time between start of feeding and
start of sampling, provided from data
a = mass fraction of cracked oil which forms
gas, must be 0 < a <_ 1
~ = 1 - 1 V"Ws x
3	*gas s
*gas 3 (*0)gas e ~'<3as/^T
The terms 4, , and Tl were obtained directly from the oil
yield model, as was	except that the subscript "oil"
was not used before. The other terms, a, *aas' an<^
!
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TABLE 4
ANALYTICAL EXPRESSION FOR THEORETICAL OIL YIELD
t	—V ' a /t/1	e — k ( t e™ t f )
V .. = V .. 1 - e * a/vA 1- 1 - e	e
oil oil
k1a/vA	kr s
Where
voil = Mass of oil leaving the bed during the sampling
period, per unit mass of the refuse fed (lb/lb).
V*0q = Value of voil for an infinitely long residence
time of the solids in the bed with no secondary
react ions.
t' = a/vA, sec
1 - e~k,t'
* ' = 1 -
k't
1 -
1 - e
-k
TS
kr :
-k(t -t )
e sr
k0 e
-E/kT
k'
K0
-E'/kT
The data from the individual pyrolysis experiments give us
the parameters	ts, t', ts-tf and T. R is the
universal gas constant defined as R = 1.987 cal/'k-mole,
with the temperature (T) in degrees Kelvin. Vqq must
be between 0 and 1.
The remaining parameters must be fitted to the data.
These are k0' , kg, E1, E, V*i;L. A complete computer fit
of these five parameters was accomplished.
10

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The ability to predict the yield of pyrolysis products
by analytic expressions is important when trying to optimize
a particular pyrolytic product, as is the case Cor several
pyrolysis systems now in operation.
The produces of pyrolysis are pyrolytic oil, char, a
low-Btu gas, and water. Depending on the feed material the
char product will contain various amounts of ash. Of the
five variables studied, temperature had the greatest effect
on the various product yields. Along with variation in the
yields of the various products with temperature, the quality
(heating value) of the different energy products changes,
as is discussed in the section on product characterization.
The remaining four variables generally produced a
perturbation about the change caused by the temperature
variation.- Bed height over the range studied had a
negligible effect on the data. The remaining variables,
feed rate, fluidization velocity, and particle size, had the
effect of perturbing the general results caused by the
temperature variation, but in the ranges studied these
variables did not show an appreciable effect on the output.
(Figure 2 shows the variation of the gas yield due to
several parameters.)
Phase II testing allowed further investigation of the
effects of particle size, fluidization velocity, and feed
rate on the pyrolysis process, by providing a greater
variation in magnitude of each of these variables. Results
indicate the same minimal perturbations about the general
temperature trends for variable feed rates. High and low
fluidizacion velocities also seem to show a minimal effect,
except in some cases where gas composition seems to be
affected. Phase I tests on tires suggested that particle
size could have a more profound effect than simply per-urbing
results about the general temperature trends. Phase II test
results on pine bark of two particle sizes also indicate a
more definite effect due to this variable.
Conclusion
The modeling of the yields of pyrolytic oil from the
various data runs shows a high degree of similarity between
the several materials that were pvrolyzed in the fluidized-
bed reactor. With some detailed work the ERCO model for the
prediction of pyrolytic oil and gas yields from the fluidized-
bed pyrolysis of waste products could be expanded to predict
the behavior of both fixed-bed pyrolysis systems, and
entrained-flow pyrolysis units.
11

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OPERATING NODEtPVROLVSIS
HATER I ALi5 AUDlJST
0.8-,-
0.6-
0.4
o.s -
o.0
KEY:
X
"T—i—I—r

f ltd
fluidiiiliun
Bad
Symbol
Atu
Vtioclly
H*ighl (m|
o
Lo
Lo
0.6
X
lii
LO
oa
Q
Hi
III
0.6
A
Lo
HI
06
O
to
Lo
0.3
~
Hi
Hi
0J
t
Lo
Hi
0J
4
Hi
Lo
OJ
R
Rtplium




• o

"i—i—i—r~

» .•

•I	1	1	1~
O .
-t—i—i—1~
300	400	500	600	700
TEMPERATURE (DEGREES C.)
GAS YIELD (UT. FRXN . OF FEED)
eee
900
Figure 2.

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Chemical Reclamation of Scrap Tires
George C. Frazier, S.-M. Chan, 0. L. Culberson, J. J. Perona and J. W. Larsen
Departments of Chemistry and Chemical Engineering
The University of Tennessee
Knoxville, TN 37916
paper presented at the conference
"Waste-to-Energy Technology-Update 1980"
Sponsored by
U.S. Environmental Protection Agency
Netherland Hilton Hotel
Cincinnati, Ohio
April 15-16, 1980
14

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Chemical Reclamation of Scrap Tires
George C. Frailer, S.-M. Chan, 0. L. Culberson, J. J. Perona, and J. W. Larsen
Departments of Chemistry and Chemical Engineering
The University of Tennessee
Knoxville, TH 37916
Introduction
Interest in the utilization of scrap cires as a source of chemicals, fuel,
and carbon black has bean increasing in recent years, due. noc only to environ-
mental regulations buc also co the fact chat chemicals and fuels based on
pertroleum and natural gas have been rising in price at rates much greater
than the general inflationary trend. Numerous attempts are therefore being
made around the industralized world to recover chemical ana fuel values from
tires (See 3erry, 1979, for a sucnnary of these developments). Most of the
current processes being developed for this purpose rely on pyrolysis of the
rubber, by one method or another, requiring the heating of the rubber co
temperatures in the range of 500-600°C, or above.
Our vork, sponsored by the U.S. Environmental Protection Agency and
supported in part by the Tennessee Valley Authority, utilizes a cacalycic-
pyrolytic process operating in the temperature range of abouc 3o0-A00°C, co
convert the scrap rubber to hydrocarbon gases, oil, and carbon black. The
catalytic agent ve have used the most is molten zinc chloride, although other
halo salts are also effective (Larsen and Chang, 1976). The results ve present
in this paper are based exclusively on zinc chloride. Molten sales have been
used previously to break down large organic molecules. For example, Zielke et
( 1966 ) developed a process vhich become known as the Consol Synthetic
Fuel (CSF) process for direct liquefaction of coal, using molten zinc chloride
a catalyst and heat transfer medium.
I" is normal practice in the chemical process industries co develop a
"conceptual process design" in the early scages of an actual project, in
15

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order to identify crucial areas requiring further development, to evaluate
various process options which may be available, to assess the overall
technical feasibility of the project, and lastly but most importantly, to
establish at the outset whether or not the process has the potential for
economic profit. In this context, the objective of the work we report on
here has been to obtain that bench scale experimental data required for the
formulation and evaluation of a conceptual process design for the conversion
of scrap tires to chemical and fuel products by molten salt pyrolysis, and
to use this design as a basis for estimating the potential profitability of
the process. Our experimental results and associated economic analysis in-
dicate that such a processing plant converting 22,500 t/yr of tires has the
potential for profit at current chemical prices, energy prices of $3-$4/MM
Btu, assuming the carbon black, the major product, is marketable at prices
in the range of at least L2c/lb. Although there are a number of process steps
requiring demonstration at the pilot plant scale, the biggest unknown at this
point in our process is the marketability of the carbon black. A pilot
plant is required to generate sufficient quantities of this material for test-
ing its suitability in products such as rubber, ink, and plastics.
Although molten salt technology is not easy, advantages of this process
lie in its relatively low operating temperature, in the range of 360-400°C,
and the fact that there is no need to pulverize the tires. However, we do
chop the tires for compaction purposes, in order to increase the reactor
throughput. Further, the relatively large pieces of fiber glass and wire
remaining after the chopping operation appear to be readily separated from
the carbon residue downstream of the reactor. A test of this separability
at the pilot plant scale is desirable.
Bench Scale Results.
A large scale reactor utilizing this technology will likely be a batch
type, which is alternately charged with rubber, flooded with salt, and sub-
16

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sequently discharged, w'e therefore simulated this procedure is our bench scale
work in order chac our processing conditions and produce yields would corre-
spond co wnac mighc be achievable in a large scale plane. Bench scale work
is necessarily small scale so we ware unable co work with large pieces of a
cira. Our reactor was 2 inches i d and 12 inches long, and cur nose con-
sistent, reasonably reproducible results were obcained when we charged che
reactor with scrips cut from a cire which were about 5/15 inch x 5/16 inch x
10 inches-, for a cocal charge weight in che range of 160 grams. A layouc of
our bench scale apparatus, constructed of 316 stainless steel, is shown in
Figure 1. The encire apparatus was heated electrically and insulated with
a calcium silicate to mimimize heat loss. The salt flowed by gravity from
che reservoir, through che reactor, co the receiver. Contact tines of che
salt with the rubber ranged from 2 to 3 minutes to 30 to 40 minutes. However,
the reaction was generally essentially over in less than 10-12 minutes, de-
pending on canper3ture. experimental runs were made -with reaction temperatures
in che range of 330 to 400"C. The carbon black residua was readily separated
from the fiberglass tire cord after a run, due to its high f"lability, by
crushing and screening. It is necessary to wash salt from "he carbon black,
but a small amount of chloride remains in both the carbon black and also in
the product oil, che latter presumably in organic form. Small particles of
carbonblack are entrained in che salt, but we have reused the sal: as nany
as four times without apparent loss in its effectiveness in promoting this
pyrolysis reaction.
After a series of exploratory and debugging experimental runs, a sequence
of four runs in che temperature range 360-390°£ gave the average percentage
product yields and analyses shown in Tables 1-3. For each 100 lb of cire feed,
17.9 lb of hydrocarbon gases, chiefly methane, but with substantial amounts
of ethylene, propylene and l-'outene, are produced, 30.7 lb of oil with an
17

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TC Veil
~\
r
JL
Purged Vent
Molten Salt
Reservoir
Flow Meter
Reac'.or
r^\
TC Well
LR
v_y
C	Capllliary
D	Drain or Discharge Valve
GR	Gas Receiver
LR	Liquid Product Trap
M	3/4" SS pipe
SR	Molten Salt Receiver
TC	lnermocouple
Figure 1. flench Scalr Flow Experiment Layout

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~
Producr Yield	Annual Yield
We. I of Feed	lb x 1CT7
Hydrocarbon Casos 17.9	0.305
Oil 30.7	1.38
C.irbon 3lac5c 44.2	1.99
Rufuse (Steelwira and Fibarglaa) "5.0	0.225
Loss* * 2.2	0.099
local 100.0'	4.5
*
^^For a plant processing 22,500 t/yr of cirea
Esciaaced as 5' of che cocal carbon black.
Table I. riscimacad Products Yields for a Molten Sale Pyrolysis Plane, based
cn che average o£ four Sench Scale Experiaencal Runs.
Component 	Anneal Yield		Mole Percent of
lbs x 10 ^ lb ooles	x 10 ^ SC7 i 10 ^	local Gas
Methane 2.52 15.75	5.66	50.1
2thylene 1.50 5.34	1.92	17.0
£:hane 1.63 5.57	2.00	17.7
Propylene 0.730 1.36	0.666	5.9
Propane 0.845 1.92	0.691	6.1
Isobutane 0.384 0.660	0.237	2.1
1-Butene 0.194 0.347	0.125	1.1
Tot*l 7.90 31.4	11.3	100.0
»
Average of Bench Scale Runs 18-21.
Table 2. Caa Analjsis and Yields for	a Molten Salt Pyrolysis Plant Proceasln;
22,500 t/yr of Scrap Tires
19

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Component	Vol use Z of	Annual Yield, gal
Total Oil
Aromaties (BTX)	27.05.	516,000
Olefins	58.85	1,123,000
Paraffins	14.10	269,000
Total	100.0	1,908,000
Density of the oil » 0.87 g/al a 7.25 lb/gal
Table 3. Major component classes in the oil and their yields,
based on Bench Scale Runa 18-21. Annual Yields are
based on a throughput of 22,500 t/yr of tires.
Product	Elemental Weight Percent
C H N S 0 CI
Oil	88.20 10.65 0.03 0.51 - 0.39
Carbon Black	87.14 2.28 - 2.10 4.84 0.94
Table A. Elemental Analysis of the Oil and the Carbon Black
from Bench Scale Run No. 18.
20

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analysis of 27.1% aromatics (3TX) are produced, and 44.2 lb of carbon black
are produced. This Latter number cakes into accounc an assumed, combined
refuse (fiber glass cire cord and steel wire) and loss of 7.22. Elemer.cal
analyses of cha carbon black and oil are shown in Table 4. The chloride
concanc of che oil is probably in organic form, but we have noc factored
the economic value of such products into che profitability analysis summarized
here. However, makeup zinc chloride salt requirements vera computed as if che
chloride values in che products were lost.
Salts such as zinc chloride are corrosive, especially if moisture is
present, and our laboratory apparatus of 316 stainless steal experienced cor-
rosion in locations when moisture (from che air) encered che system during
the frequent opening required of an experimental apparacus of this cy?e.
However, ve have provided precautions, such as purges and dry storage for che
feed tires in order to aimimize corrosion problems in those parts of our
conceptual design commercial plant which come into contact with che hoc sale.
Conceptual Design Processing ?lant
Our design basis is a plant which will process 22,500 c/yr of cires, wich
a 90% on-scream factor, and an assumed carbon black recovery factor of 9 52.
This throughput corresponds to 68.5 t/day, which may be on che lower end of
Che size scale for a plant of chta type which can be economically feasible.
A larger plant would be more attractive economically, buc would also be
limited co a fewer number of locations, due to the cost of transporting scrap
cires over larger distances.
The conceptual layout for this plant is shown in Figure 2. Dry storage
is provided for che scrap cires, where chey are chopped inco 12-13 inch pieces
in order co increase cheir bulk density, chus allowing greacer chroushpuc for
a given reactor size. The batch reaccor is charged through a lock hopper
21

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lock
llonper
7 I Chopper
2P.5M i/yr ' 	
Vapor	
Puroe Gas
Condenser
Compressor
Reactor
Hoi ten
Salt
Reservoir
Product Oi1
Residue
Salt
Oil
Receiver
Produc t
Gas
Receiver
Salt
Res Idue
Hopper
Air
Flue
Dried
ResIdue
Oryer
\ . .Recycle
Filter —{13 - *»¦
Salt Cake
Condensate
	
Recycle Liquor
Maanet1c
Separator
Screenino
Carbon ti!acV~
Storaqe
Hopper
Ocsinnod for a Scrap lire throughput of ??.SOO t/yr.
Tire Cord
to Baler
Carhon Black Product
. 3s		
To S i /r HpiJih i ion

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co prevent noise air from entering the system. The zinc chloride sale is
heacad '0/ a direct-fired heater and forced into	the reactor by compressed,
dry flue gas, thereby eliminating the need for a salt pump and valves, which
would be troublesome in a system of this type. The reactor loading, reaccion,
and discharging cycle time is estimated to be about 1 1/2 hours and at the
end or the cycle, the gas pressure on the salt reservoir is released, and the
sale drains by gravity from the reactor to the reservoir, until the next cycle.
The reaction temperature is in the range of 430±20°C although we have not
done a sufficient amount of work to deceraine whether or not this is optimum
with respect to product yields and quality. For example, carbon black produced
by "his process at too low a temperature tends to be high in volatiles, whereas
too high a reaction temperature tends to favor a high yield of methane in the
produce gas at the expense of the more valuable olefin gases.
Down stream of the reactor, the product vapor is processed by conven-
tional technology to a gas stream and an oil stream both of which are, pre-
ferabl/, piped "over the fence" to existing refineries rather being stored
and processed on site. Such an arrangement limits ehe location of tire pro-
cessing plants co those locations in which gas (ethylene) and petroleum
refineries already exist, as shown in Figures 3 and 4.
Returning to Figure 2, the 3olid refuse (carbon black, fiber glass, steel
wire) is washed to remove salt.devacered, dried, crushed, and the wire and
fiber glass are separated first by a cagnetic dann and then by a screen to
retain the fiber glas "fluff". Top size of the carbon black at this point
is about 3/3 inch, and requires grinding (not shown) to customers' specifi-
cations. Conventional technology is used throughout this process stream,
although the process needs Co be "piloted" in order to demonstrate the
separability of these solids and co escablish the degree of salt recovery in
the two stage wash tank.
23

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Figure 3. Location of Ethylene Plants
in the Continental U. S.
Figure 4, Location of Petroleum Refineries in the Continental U. S.
24

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Sale is also recovered from che wash water by conventional technology:
vacuum evaporation, crystallization, filtering, and drying, for racycle Co
che sale reservoir. The saic liquor is diluted ana recycled co che wash
tank, eliminating che need for disposal of salty, "black water". The only
appreciable salt loss from che system is chat carried by che oil and by che
carbonblack, estimated co be about 4.3 x 10^ Ib/yr, for this plane. The over-
all plane material balance is shown on Figure .2.
Economic Analysis and Profinability Escimaces
The major components of che	conceptual plant were sized for a
throughput of 22,500 c/yr of tires and their costs (late 1979) were estimated
in accordance vich che data and procedures given by Petsrs and Timerhaus
(1963) and by Guchrie (1969) , using a Marshall and Seevens cose index of
622.7 (fourth quarter, 1979). The Fixed Capital requirements of 4.31 MMS were
then computed according co che summary shown in Table 5. Annual operating
costs were also estimated in accordance with che ratios given by Pacers ana
Tinmerhaus and are sunaarized in labia 6. The cost of the feed tires is lass
certain and depends on numerous factors, an important one of which is hauling
costs (3erry, 1979). We therefore considered this cost a parameter in our
analysis, ranging from 20 co 4Q S/c.
Our initial analysis based on the sale of ail products for fuel indicated
there i3 little possibility (short of a "negative" cira reed cost) a plant of
this type could be profitable with energy prices in che range of 3-4 S/MM 3tu.
As our next case we considered recovery (and marketability at late 1979 prices)
of che major components having value as chemical feed stocks, Cram che product
screams: carbonblack, olefin gases, and the aromatic oils (BTX). The re-
maining gas and oil in che product stream vas assigned fuel values. Prices for
che chemical products were taken from Chemical Marketing Reporter (December 10,
1979), and those products were discounted up co 90S for refining and separation
25

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A. Plane Physical Costa
Process Equipment, Delivered (E)	$1,092,000.
Installation (.45E)	491,500.
Insulation (.08E)	87,400.
Instrumentation (.18E)	196,600.
Piping (.25E)	273,000.
Electrical (.125E)	136,500.
Buildings (.5E)	546,000.
Site with improvements (.14E)	152,000.
Auxiliaries (.4E)	436,900.
Plane Physical Coat (P)	$3,412,000.
8. Indirect Cost3
Engineering and Construction (.15P)	511,800.
Contractor's Fee (0.1P)	341,200.
Contingencies (.15P)	511,800.
Total Indirect Co3t3 (I)	$1,365,000.
C.	Initial Charge of Zinc Chloride (C)	30,000.
D.	Plant Capital Cost (P + I + C)	$4,810,000.
Table 5, Fixed Capital Requirements for a Molten Salt Pyrolysi9 Plant
Processing 22,500 t/yr of tires, in late 1979 dollars.
A.	Labor and Supervision (Salaries and Wages) $295,000.
B.	Plan Overhead (60Z of Sal. and Wages)	177,000.
C.	Utilities (17.52 of Total Product Cost)	513,600.
D.	Chemicals, Makeup Zinc Chloride	197,800.
(4.71 x 10s lb/yr at 42c/lb)
E". Insurance (1Z of Fixed Capital)	43,100.
P. Taxes (3Z of Fixed Capital)	144,300.
G.	Maintenance (5Z of Fixed Capital)	240,500.
H.	Operating Supplies (15Z of Maintenance)	36,100.
I.	Depreciation
Machinery and Equipment 0 lOZ/yr	380,000.
Buildings 0 3Z/yr	29,300.
J. Interest (8Z of Fixed + Working Capital)	461,800.
Base Operating Coats	$2,524,000.
Tabl? 6. Annual Base Operating Coses for 22,500 t/yr MSP Plant.
26

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In view of che face that "he grade of our carbon black has vac to be estab-
lished, ve also considered its value to be a paramecer in chis study. The
lower end of che range used was established using che price of che lowest
grade reported in CMS. (Dec. 10, 1979) of 19.2 c/lb and then discounting chis
by .02 c/lb as a reasonable, lower estimate of che value of chis product at
che current time.
Working capital was assumed to be 20% of fixed capical, incerest ac 8" of
total capical, and Sales, Corporate Adminiscracion and Research (SAR) fees
of 10% of revenues 'were charged against che plant. A case analysis sheet is
shown as Table 7, and che profitability (lose in seme cases) is sunmarized
in Figure 5, in terms of Recum on Investment (RCI), as affected by scrap
I
tire and purification costs, and carbon black and fuel prices. Additional dec3'!,
of chis work are provided in our final report (Frazier, et al 1980).
Acknowledgement
This work was supported by Grant Mo. USt?A R80&321. Additional support
was received fron the Tennessee '/alley Auchoricy, Cost information was
supplied by International Baler Corporation, Rawls Division of the Macional
Standard Company and the W. S. Tyler Division of Combustion Engineering.
Carbon Slack Samples were characterized by the Cabot Corporation. .Mr. Robert
Wiesen provided timely assistance in che laboratory. Vithose ^3e contribution
of the above Deoole ana organizations, this project could not have been
completed.
27

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TIRES
PURIFICATION
FUELS
CARBON BLACK
40 $/t
30	 %
_4	 $/MKBTU
15	 C/LB
MMS/YR
REVENUES
C2H4,C3H6,C4H8,BTX	1JL2
FUELS	I¦24
CARBON BLACK	2.99
REVENUE TOTAL	5.35
LESS 10% SAR	0.54
NET REVENUE	4.81
OPERATING COSTS
BASE (FROM TABLE 6)	2.52 MM$/YR
PURIFICATION	.34
TIRE RAW MATERIALS	.90
OPERATING COST TOTAL	3.76
GROSS PROFIT	1-05
LESS 46% INCOME TAX	0-43
AFTER-TAX PROFIT	0-57
% RETURN ON $5.77 MM INVESTMENT	9.9
Table 7. Case Analysis Sheet for a Molten Salt Pyrolysis Plant Sized for a
Tire Throughput Rate of 22,500 t/yr.
28

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T
"~7
7
1
T
1

30 Purification



GO
90
Cost, %
Carbon Ulack Price, tf/lb
15	18
Fuel Value
$/MM Btu
Scrap Tires Cost, $/ton
Estimated Profitability of a Molten Salt Pvrolysis plant with a Scran Tire through nut of
00 /yi se< la 179 :es Co

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References
Berry, Reginald I., Chem. Eng., p.30, Dec 31, 1979.
Frazier, George C., S.-M. Chan, 0. L. Culberson, J. J. Perona, and
J. W. Larsen, "Chemical Reclamation of Scrap Tires", Final Report on EPA
Grant No. USEPA R804321, Spring 1980.
Guthrie, K. M., "Capital Cost Estimating", Chem. Eng. p. 114, March 24, 1969.
Larsen, J. W. and B. Chang, Rubber Chem. and Tech., 49_, 1120 (1976).
Peters, Max S., and K. D. Tiinmerhaus, Plant Design and Economics for
Chemical Engineers, McGraw-Hill Book Co. New York, Second Edition, 1968.
Zielke, C. W., R. T. Struck, J. M. Evans, C. P. Costanzy, and E. Gorin,
Ind. Eng. Chem., Process Des. Dev. 5, 151, 158 (1966).
30

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THE CALIFORNIA MOBILE PYROLYSIS SYSTEM
Dr. Herbert M. Kosstrin,
Principal Scientist
Energy Resources Company, Inc.
Cambridge, Mass.
Introduction
A prototype mobile pyrolysis system to convert agricultural wastes
to transportable fuel products is currently under construction. This demon-
stration project is being sponsored by the U.S. EPA and the State of California.
The Solid Waste Management Board of the State of California is directing the
California portion of the operation, and the Fuels Technology Branch of the
Industrial Environmental Research Laboratory, Cincinnati, Ohio, the EPA share.
Energy Resources Company, Inc. of Cambridge, Mass. is the prime
contractor for the project. Major subcontractors are Litwin Engineers of
Houston, Texas, Valley Fabrication Engineers of Fowler, California, and
Alpha National of El Segundo, California.
The mobile pyrolysis unit is a fluidized-bed pyrolysis system for
the conversion of various agricultural wastes into a storable energy product.
The waste products used by this system will be from the Central Valley of
California. The waste conversion system is designed to be built on two
low-boy trailers in order to improve the economics of converting widely
dispersed agricultural wastes to useable fuel products. The pyrolysis system
produces three fuels products, a low Btu gas, a pyrolytic oil, and a char.
The unique features of this system are the mobility of the unit
and the total self-sufficiency from outside fuel sources after start-up.
The system uses the pyrolytic gas generated during waste-to-fuel conversion
process to operate a gas turbine cogeneration system. The cogeneration
system produces the required electricity to operate the system and the heat
necessary to dry the incoming feedstocks. Also, after the fluidized-bed
32

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reactor is heated up co temperature with a scar-up fuel, a portion of the
waste is combusced co supply che heac for che fluidized-bed reactor. In
addition, Mo. 2 fuel oil is used as che initial scrubbing or cooling liquor
in che oil separation system. As soon as sufficient pyrolytic oil is pro-
duced, it is utilized as che liquor. In chis manner che mobile pyrolysis
unit is independent of outside fuel sources.
The outputs of chis mobile pyrolysis system are che storable ana
transportable fuel products, pyrolytic oil, and pyrolytic char. These tvo
products have a greater energy density than the wastes from which chey are
generated, and therefore, can be economically transported. In addicion,
these products of pyrolysis are more uniform in composition than their
respective feedstocks and can be utilized by existing fuel systems, whereas
use of the individual wastes would require special boiler design.
Background
The concept of a mobile pyrolysis waste conversion system resulted
from programs sponsored by both the United Scates Environmental Protection
Agency and the State of California Solid waste 'lanagemenc Board. The initial
£?A program, which proved chac stationary pyrolysis of waste products was
an acceptable means of converting waste products co fuels, was carried out
under the auspices of the Fuel Technology 3ranch of IZRL-CIN. In this
program both fixed bed and fluidized bed pyrolysis processes were tasted
and evaluated for several years.
During this time period the State of California Solid waste Manage-
ment 3oard (SVM3) was concerned with disposal of various agricultural waste
products. The waste products which need disposal are cotton gin trash,
rice straw, orchard prunings, manure, and logging and lumber-mill wastes.
These waste products are spread throughout the encire state. In addition,
each of chese waste produces are generated. during different seasons of the
year. The geographic and seasonality dispersion led the SVM3 to conduct a
series of studies evaluating stationary vs. mobile disposal systems.
33

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Two major findings convinced che SWMB that a mobile unit was
preferred over a stationary system. One is the high cost of transporting
low density, wet waste products. The second is that a fixed system might
be located in a portion of the state that is not generating wastes year
around and consequently, might not operate for a substantial part of the
year. A State of California report, SB 1395 "Agricultural Economic Feasibility
Analysis", gives the costs of transportation of the various waste products.
The study which resulted in this report found that the cost of transporting
these low-density wet wastes was prohibitively high. And that only a mobile
type system was economically reasonable.
As a result of these independent studies the State of California
and proposed a mobile pyrolysis waste disposal system that converts these
wastes into useable forms of energy.
The System
The major elements of the mobile pyrolysis system can be seen in
the simplified flow sheet (Fig. 1). The major system components are feed
preparation (sizing and drying), thermal decomposition (fluidized bed
reactor), product separation (char and oil), and electrical cogeneration
(gas turbines). The individual subsystems are integrated to as large an
extent as possible in order to maximize the overall efficiency of the system.
The physical system is designed to operate on two low-boy trailers.
Trailer If 1 contains the fluidized bed reactor and product separation systems
and auxiliaries. Trailer it2 incorporates the feed preparation and electrical
cogeneration system. The trailers are forty-eight feet long and forty-seven
feet long, respectively. The tractor and trailer combination weighs less than
eighty thousand pounds each and meets all of the California transportation
regulations for over-the-road operation.
The central element of the mobile pyrolysis unit is the fluiaized-
bed reactor. The reactor converts agricultural and forestry waste products
to useable fuels. The unit uses a refractory sand as the inert fluidizing
medium, and can handle feedstocks with moisture contents as high as 55 percent.
34

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The feed preparacion system reduces che moiscure concenc of che
feaascock entering che reactor co much lass than this maximum amount. This
sub-system is composed of a standard hammer-mill-cype shredder and a pneu-
macic-cype cower dryer. The drying systam has been adapted from standard
designs of che cotton ginning industry.
The product separation sub-system collects che storaole and trans-
portable fuel products. The dry mechanical collector (cyclone) captures che
char (density 10-15 lbs/ft"^), and the Venturi oil scrubber collects the
pyrolytic oil (65-75 lbs/ft?). The Venturi oil scrubber is a modification
of a standard wet scrubbing system. The principal change is in the flow
races of the scrubbing medium and che types of pumps employed. The ouinps
are capable of pumping a high viscosity fluid.
The final system coraponenc is che electrical cogeneracion system.
A gas turbine uses che low-Btu gas (150 Btu/scf) generated during che pyroiysis
process co generace che required electricity for the several motors of che
entire unit. The exhaust from the turbine is mixed with cooling air and then
used as che heat source for the drying system. To integrate che system more
completely, che gas turbine package supplies che required fluiaizacion air
for che reactor sub-system.
The Products
The fluidized-bed pyrolysis systam produces thrae fuel products—
a low-3tu gas, a pyrolytic oil, and a pyrolytic char. As can be seen in
Figure 2, "he quantity of che products can be varied by changing che operating
temperature of the reactor. The operating temperature of che mobile pyrolysis
systam was selected in order to maximize che storable fuel products (char and
oil) while producing a low-Btu gas that could be burned in che electrical
generation su'o-systea.
The gas quality chat can be burned in che gas turbine engines can
be as low as 100 3cu/scf. The mobile pyrolysis unic is designed co produce
a gas of 150 Btu/scf qualicy. During scarc-up che turbines will be tested
35

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to determine the minimum gas quality that can be tolerated. As the turbines
are shown to be able to burn a low-quality gas, the reactor conditions can
be varied to produce a larger portion of storable oil product.
The char product resembles pulverized coal. The exact physical
nature depends on the waste material from which the char is derived, and
the temperature at which the char is produced. If waste wood is the feed-
stock, and the temperature of the reactor is approximately 1000 F, the char
will have a heating value of approximately 13,000 Btu/lb, an ash value of
less than 10 percent, and a particle size ranging from 1000 microns to 50
microns or less. The volatility of this material is approximately 20 percent.
This char makes an excellent feedstock for charcoal briquets.
The oil product is similar to a heavy residual oil that is highly
oxygenated. Its heating value ranges between 11,000 and 13,000 Btu/lb.
The handling properties of the pyrolytic oil made from wood are different
from a typical residual oil. The viscosity and corrosivity are higher and
the material undergoes chemical changes when stored at elevated temperatures.
However, the sulfur content of this oil is negligible which is of considerable
importance today.
System Efficiency
The principal objective of the mobile pyrolysis system is to dispose
of waste products while producing a transportable fuel product. The energy
flow diagram (Figure 3) shows the split in the energy product for the design
case in which the quality of the low-3tu gas is 150 Btu/scf. This condition
yields a storable energy fraction of 49 percent of the incoming feed. The
additional recoverable energy in this case is used for drying of the feedstock
or it is vented to the atmosphere.
The percentage of storable energy can be increased if the quality
of the gas being burned in the gas turbine can be reduced.
The total system efficiency is increased when operating in a
region where the low-grade heat being rejected by the oil scrubbing system
and excess turbine exhaust heat can be utilized. This situation does occur
36

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when ooeracing ac a cotton gin or sawmill. This low-grace heac can be used
co supply che energy for preheat of a steam syscem or a hoc water system.
Schedule
The mobile fluidized-bed pyrolysis syscem is scheduled co be
completed by early May, 1980. The system will chen undergo a chree-monch
shakedown on sawmill waste ac a sice near che fabrication shop. After
complecion of che shakedown phase che unic will proceed on che remainder
or* che 9-month cescing schedule on che remaining waste produces, coccon gin
crash, rice straw, and feedloc wastes.
During this casting period che entire system will undergo complece
analysis as to environmencal amissions, operating characteristics, fuel
product quality, and overall system economics.
37

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T1IOSTOCK
0
JfTL
o
sunt doen
onvtn
rttncn
pvnoi y/fh
enAnsrrAnATon
oil cowofNsrn
OIL cooi-Fn
rowrnisson
cownusTon
TiinniNE
CJlNEflAIOn
fucl coMpncsson
TUHOO FAN
¦J IJ LI III
CAS

-------
0 00
Oil YicHd
	j	
PRODUCT YIELD FLEXIBILITY
AT VARIOUS TEMPERATURES
0 00
n"
y o-
?;o/io
o
I-*
X) 5
V >
lL o0.20
o	
il.	.«•
0.00

ooo° r i,ioo°p i /i oo° r i.7oo"f
Char Yinkl
Gos Yield
2 <« C10
v ^
"0.20
«¦ o 0.70

o S 0/10
000° I" 1.100°F 1.400°r 1,700"F
boo<>f
1,100° F
1/100"F 1.700"F

-------
FLUID ono
CONVERSION
PROCESS
r
CHAR :| 27%
27%
OIL
				
f	\J

turbine
Mcn&llNEIl '2%
34%
1%
fxmausi
II HAT
PROCESS
CLECrniCITY
STORAOLE
'enf(u;y
i RECOVERABLE
' ENERGY
t100°F
orftHiDfHjnonraSntJ^ElflnDM&OiFDmiJfitrDnnfQimraQDnd -»%
LOSSES

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THERMOCHEMICAL CONVERSION OF BIOMASS TO GASOLINE
J. P. Diebold and G. D. Smith
Naval Weapons Center
China Lake, CA 93555
ABSTRACT
This noncatalytic process involves the low pressure,
selective pyrolysis of organic wastes to gases containing
relatively high amounts of ethylene and other olefins.
After char, steam, and tars are removed at low pressure,
the gases are compressed to 450 psia (3100 kPa) for
purification. The concentrated olefins are then further
compressed to 750 psi (5200 kPa) and fed to the poly-
merization reactor where they react with each other to
form larger molecules, 90% of which boil in the
"gasoline" range. Using organic feedstock derived from
trash, gasoline was produced on a bench scale system
which had the same appearance and distillation charac-
teristics as gasoline made from pure ethylene which had
an unleaded motor octane of 90. Preliminary economic
analyses indicate that the process is currently compe-
titive with petroleum derived gasoline. This program has
been funded by the U.S. Environmental Protection
Agency.
INTRODUCTION
The petroleum resources of the free world are becoming
increasingly scarce and expensive. As the search for new
oil goes further out to sea and deeper in the ground, this
new oil will be increasingly expensive to produce. Many
of the existing oil fields in some countries apparently
will not be pumped at their maximum rate in an effort to
save that oil for future generations when the price will
be presumably higher. Thus, it appears advantageous to
develop sources of synthetic petroleum and in particular
synthetic gasoline. Due to the high volumetric energy
content of hydrocarbon liquids, they would have been
invented for mobile transportation if* they had not been
naturally occurring. Usually the term "synthetic
petroleum" brings to mind coal and/or oil shale
liquefaction. However, these processes will involve a
considerable amount of environmentally questionable
strip mining and are normally considered to require a
large amount of scarce water resources. The process to
be discussed in this paper involves the use of organic
wastes and/or biomass in a noncatalytic selective process
to produce unleaded, high octane gasoline. Byproducts
are fuel oil, lubricating oil, ash, water vapor, and carbon
dioxide. Commercial sized plants would resemble small
oil refineries in many aspects and could be widely
deployed in order to be near the feedstock source.
The advantage of producing gasoline rather than other
fuel forms becomes apparent by comparing common fuels
on a relative wholesale value basis. If a wholesale value
of $1.00 per unit of energy is assigned to natural gas for
interruptible commercial usage, then in 1975 the value of
noninterruptible domestic natural gas was $1.42 per unit
of energy. Number six fuel oil was $3.08, while the value
of gasoline was $5.48 per unit of energy. Recent relative
increases in the value of natural gas have reduced the
ratio of gasoline to natural gas prices temporarily.
However, the widely predicted continuation of today's
petroleum shortage will cause the value of gasoline to
escalate at a rate much greater than boiler fuels. This is
because, although coal can again become the primary
boiler fuel for the nation, coal fueled automobiles naving
today's performance are not being actively considered.
The conversion of organic waste to automotive fuel was
consequently investigated for remote military instal-
lations in a Department of Defense Advanced Research
Projects Agency sponsored program because of the high
potential value of the product. The synthesis of
methanol from organic wastes was evaluated in detail
with mass and energy balances developed about two
different flow diagrams. This approach would have
pyrolyzed the organic fraction to form synthesis gases
which would then have been compressed, purified, and
catalytically reacted to form methanol. During the
course of this study (1), several references were found
which indicated the possibility of using pyrolysis to form
a significant amount of low molecular weight
hydrocarbons rather than just carbon oxides, methane,
and hydrogen. These gaseous hydrocarbons of interest
were predominantly ethylene, propylene, and other
olefins.
In the 1930's the oil industry began to extensively
pyrolyze ("crack") crude oil to increase the yield of
gasoline. By-products of that process included large
amounts of ethylene, propylene, and butylene. Extensive
research was performed on the utilization of these by-
product gases which led to the commercialization of
their conversion to gasoline by both catalytic (2) and
non-catalytic (3) processes. The gaseous hydrocarbons
were compressed, purified, and then heated such that
they reacted to link up with themselves to form the
larger gasoline molecules by polymerization. This
process produced a liquid which was over 75 percent
gasoline. The proposed process substitutes solid organic
wastes for the crude oil feedstock, but otherwise
parallels the petroleum process used to make polymer
gasoline. Due to the high ethylene content of the olefins
formed during pyrolysis of cellulosic materials, the
thermal or non-catalytic polymerization was chosen for
42

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this process because the traditional catalytic method
polymerized ethylene with difficulty.
The overall process for converting organic wastes to
gasoline consists of: first, the pyrolysis of the wastes to
gases containing large amounts of olefins, i.e. ethylene,
propylene, etc.: second, the compression and purification
of the olefins: and third, the polymerization of the
smaller olefins to form larger gasoline molecules.
Overall this amounts to a process which removes the
oxygen from the cellulosic wastes to produce a gasoline
consisting of hydrocarbons. Most of the rejected oxygen
is in the form of carbon dioxide.
The critical technology that this program needed to
demonstrate was the pyrolvsis of cellulosic organic waste
materials into gases containing large amounts of olefins
and their subsequent processaoility. If the selective
pyrolvsis could oe verified, and demonstrated, then the
remainder of the process to make gasoline was thought
to be relatively straightforward due to industrial
experience with similar processes. In effect, the process
parallels that of an oil refiner/ with the most significant
difference being the use of today's cellulosic waste
material rather than eons-old organic matter (crude oil)
as a feedstock.
The potential impact this process could have on the
gasoline consumed in the United States appears to be
substantial. Assuming that this process will undergo a
traditional developmental or scale-uo period followed by
a well financed program with high national priority,
widespread deployment of conversion plants could be
accomplished by 1998. A recent Market Oriented
Program Planning Study by the Department of Energy
(DOE) estimated the U.S. gasoline consumption in 1990
at 115 billion gallons (4). If 10% of the land currently in
forest, pasture, or range usage having at least 25 inches
ot" precipitation and less than 30?6 slopes were to be
developed for silvicultural energy farms, approximately
2S°6 ot the gasoline consumed could be produced from
the resultant biomass (5). Another 13% of the projected
gasoline consumption could be produced from crop
residues and spoiled forages (6); If the trash generated
by 120 million people were to be converted to gasoline,
4% of the 1990 gasoline consumption would result. From
these three biomass sources, slightly less than half of the
projected 1990 gasoline consumption could be produced
by the conversion process described without impacting
food production to any extent. To determine the net
energy produced by the overall system including energy
inputs to grow, harvest, transport, and process biomass
into gasoline requires a very specific analysis for a given
site and is outside the scope of this paper. However, the
process would have the best economics where the
biomass is a waste by-product and wriich now requires
energy for its disposal.
Initial preliminary economic analyses looked very
promising for fairly small cities to rid themselves of
trash so the Environmental Protection Agency (IERL,
Cinn.) was contacted to generate interest in this
economical approach to trash disposal. As a result of
their interest in this process, an interagency agreement
(EPA-IAG-D5-0731) was written for NWC to pursue the
technical and economic feasibility of converting organic
wastes to gasoline by evaluation in a bench-scale unit (5
kg/hr). This EPA effort was begun in June 1975 and has
been continuing.
EXPERIMENTAL
Pvrolvsis
Figure 1 shows the currently evolved pyrolysis schema-
tic. A finely ground organic fraction of municipal solid
waste is continuously fed by a one-inch screw feeder. At
the end ot the screw feeder, the feed is fluidized and
conveyed by a carrier gas stream (normally carbon
dioxide) to the steam ejector. The mixture of solid
waste, carrier gas, and steam then enter a long, red-hot
3/4 inch diameter tubular reactor. Reactor lengths of 2
and 5 meters resulted in pyrolysis times of aoout 50 to
ISO milliseconds, respectively. The char is removed
from the pyrolysis stream in a three inch diameter
cyclone. The steam and tars are condensed out of the
pyrolysis gas stream bv the water quench system. The
noncondensible gas stream volume is measured by an
orifice flow meter and then either flared off or fed into
a three stage compressor for storage at high pressure.
This system pyrolyzes a nominal 5 !
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The composition of the pvrolysis products has been found
to be a function of the combination of temperature,
residence time, and especially the dilution of the solid
wastes by inert gases inside the reactor. As shown in
Figure 2, the total hydrocarbon product (other than
meth8ne) can be varied by as much as 165% depending
upon the relative dilution of the pvrolysis gases. Using
the more favorable combination of these variables, a
pvrolysis product distribution such as that represented in
Figure 3 can be attained using organic material obtained
from municipal solid wastes. Slightly more than half of
the energy contained in the organic waste can be
recovered in the gasoline precursors. About one third of
the energy is recovered in the "medium Btu" by-product
gas stream of carbon monoxide, methane, and hydrogen.
About one-seventh of the energy is recovered in the
char, which has a heating value similar to lignite coal.
7M°C PVROLYSIS TEMPERATURE
75a
110
700
7«0
S.1M PrflOUSIS coil
ECO II IT —511 FEED
(1% MOSITURE)
-
2
t	U	10 <20 1(0 IOC
I DRY ECO H/M3 GASES
Fig. 2. Pvrolysis Products as a Function of Dilution
•It ITU
SCF IT-ntOOUCT GMES
H, UN
GASOIINI KUCUKSOHS
ism
Fig. 3. Pvrolysis Product Energy Distribution
Pvrolvsis Discussion
Pyrolvsis of cellulosic materials has long been recognized
as the result of several competing reactions taking place
simultaneously. At low temperatures of 200 to 300 C,
the predominant reaction is of dehydration to form char
and water vapor. At intermediate temperatures of 300
to 600 C the predominant reaction is a depolv-
merization or chain cleavage reaction to form
ievoglucosan tars. At elevated temperatures,
gasification is the predominant reaction to form
combustible volatiles. (7) This gasification reaction
itself appears to have at least two major competing
reactions: a) to form olefins, carbon monoxide,
hydrogen, and methane; and b) to form thermally stable,
water soluble, oxygenated compounds. The data suggest
that the olefin forming reaction is favored when the
partial pressure of the pvrolysis products is reduced by
the addition of a relatively inert carrier gas, e.g. carbon
dioxide, steam, methane, nitrogen, or carbon monoxide,
or mixtures of these gases with hydrogen. It is
interesting to note that although the quantity of gases
produced can be varied by the relative dilution, the
relative molar ratios of the gaseous species after water
washing are relatively constant.
The by-product gases could be used to fuel stationary
internal combustion engines to generate shaft power for
the compressors and shredders, as well as to fuel the
pvrolysis furnace along with the by-product char. As was
mentioned, it was. found that the use of steam to dilute
the pyrolvsis gases results in a higher conversion to
gasoline precursors. It now appears that the process will
be optimized by making as much steam as possible by
energy recovery from hot gas streams as well as by
utilizing all of the char and the by-product fuel gases for
process energy. This will result in only gasoline, fuel
oils, and lubricating oils as the products from the organic
fraction. These products will be readily marketable
compared to char, pyrolytic oils, or "medium Btu" gas.
The generation of high pressure, superheated steam to
cogenerate shaft energy and low pressure process steam
may optimize the process.
It is interesting to note that the pyrolvsis conditions
found to be optimum for municipal solid wastes are
coincidentally similar to those used by the petrochemical
industry to pyrolvze naphtha or crude oil to form
ethylene: e.g. about 750 C (M40Q F), steam dilution,
pvrolysis times of less than a second, and iong tubular
reactors having inside diameters of less than five cm (8,
9, 10). It is even more interesting to note that if the
carbon monoxide and carbon dioxide in the pyrolvsis gas
are ignored, and the remaining products are then
normalized, that the relative weight percentages of the
pyrolysis products from naphtha (8), solid wastes, and oil
shale (11) are very similar, as shown in Figure 4. it
appears that the molecular fragments from the pyrolysis
of both cellulosic ana large hydrocarbon molecules are
very similar and that they achieve a similar short-lived
"equilibrium" between the products. If not rapidly
quenched, this psuedo "equilibrium" changes bv the low-
pressure, high temperature polymerization of ethylene,
propylene, and butvlene to form about half benzene and
half aromatic tars with the evolution of hydrogen (12). [f
the pvrolysis system has a very long residence time, the
benzene and tars further react to form char and
hydrogen — the last mentioned being the traditional
products from charcoal kilns, along with carbon
monoxide.

-------
'MSW (ECO ID
err. /OIL SHALE
NAPHTHA v j; kr
(WEIGHT PERCENTAGES CALCULATED AFTEfl CO ANO C02 DELETED)
Fig. 4. Pyrolysis Product Comparison
Polymerization with Pure Ethylene
To avoid the tar formation during polymerization, lower
temperatures can be employed so that the gasoline
fraction in the product is optimized. However, in order
to maintain reasonaole reaction rates, the pr^sure nust
be increased. Temperatures of 400 to 500 C (730 to
950 r) and pressures of 4800 to 5900 kPa (TOO to 1000
psi) were often employed commercially (13, 14). To gain
insights into the exothermic polymerization reaction, an
experimental reactor was constructed as shown in Figure
5. This polymerization effort was conducted
concurrently with the pyrolysis development, so no
purified pyrolysis gases at elevated pressures were
availaole for use. Since ethylene was the largest single
constituent in the gasoline precursors found in the
pyrolysis gases, bottled ethylene was purcnased and Laed
for this study. The ethylene was regulated into a one-
half inch ciameter stainless steel tuoe wnicn had ;een
coiled and placed in a constant temperature, fluidized
sand oath. The sand bath served to initially 'leat the
coiled reactor until the exothermic reaction was
initiated, after which the bath served to remove Lie heat
generated. The ethylene slowly moved down the length
of the reactor for a few minutes while polymerizing.
The polymerized gases were then cooled to condense out
the gasoline and oils. SoncondensaOle gases were
measured and then flared off. Conversions per pass were
as high as 30 percent. The liquids formed had very low
viscosities and when distilled produced aoout 90 oercent
it
REMOTELY OPERATED
VALVE
T
V
oTo
9^
POLYMERIZER COIL
! «N-
I I 1
AIR
CONDENSER
PRESSURE
REGULATOR
TO
FLARE
ROTAMETER
VENT
U L
ETHYLENE
HIGH TEMPERATURE
FLUIDIZED SAND BATH
GASOLINE
RECEIVER
™ig. 3. Experimental Polymerization Reactor

-------
gasoline. This distilled gasoline fraction was tested
following the ASTM motor method and found to have a
90 octane rating in the unleaded condition (the research
method would have resulted in a slightly higher octane
number). The higher boiling liquids will yield a fuel oil
and a lubricating oil fraction.
Based on the pyrolvsis and ethylene polymerization
experimentation it is estimated that 0.28 liter of gaso-
line and 0.03 liter of oils will be produced per kilogram
of 90% by weight organic material (68 gal/ton gasoline, 8
gal/ton oils). The amount of lubricating oil in the oils is
currently conjectured to be fairly small, but with a high
potential total value due to its reported excellent
viscosity characteristics (15).
Bench Scale Purification and Polymerization
The bench scale pyrolvsis gas purification and poly-
merization flow diagram is shown in Figure 6. The
pyrolysis gases are first compressed to 3100 kPa (~450
psi). The purification starts with the removal of carbon
dioxide, hydrogen sulfide, and other water solubles with a
hot, aqueous solution of potassium carbonate (L6). Next
the desirable olefins are absorbed in an organic solvent
with the by-product fuel gases passing through
unabsorbed. The olefin rich solvent is then heated to
drive off the relatively volatile olefins (17). The purified
olefins are then further compressed to 5200 kPa (~-750
psi)Qand fed ^nto the polymerizing reactor held at about
450 C b350 F). The polymerizing reactor consists of a
3 meters long by 1.3 cm diameter 316 stainless steel tube
(10 ft by 1/2 in dia) immersed in a boiling sulfur bath.
The boiling sulfur bath has an extremely high heat
transfer capability and serves to maintain a constant
temperature as it removes the heat of polymerization.
The polymerization reaction proceeds under these
conditions of heat and pressure without catalysts to form
a product consisting primarily of gasoline. After
polymerization, the hot gasoline vapors are cooled,
condensed, and stored. Unpolvmerized olefins can be
recycled.
This bench-scale system is in the final stages of
debugging. The hot carbonate system for carbon dioxide
removal is very selective and has resulted in a carbon
dioxide stream having a purity of greater than 99% by
volume with the primary contaminant being acetylene.
The potassium carbonate solution is easily regenerated,
although it does require a considerable amount of energy
to boil the solution at 120 C (250 F). The hydrocarbon
absorption system needs additional tuning, but has
resulted in a byproduct gas stream containing 20%
hydrogen, 5% nitrogen, 1L% methane, 61% carbon
monoxide, and 2 to 3% gasoline precursors (mostly
ethylene and propylene). The hydrocarbon stripper
system also needs some additional tuning, but it has
resulted in an enriched stream containing as high as 48%
gasoline precursors with 4% hydrogen, 1% carbon
dioxide, 1% nitrogen, 16% methane, and 29% carbon
monoxide as the impurities.
The effect of these impurities in the polymerization was
to lower the partial pressure of the reacting olefins to
slow the bimolecular polymerization reaction. A longer
residence time is indicated in the polymerizer reactor
depending upon the relative purity attainable from the
gas purification system. Using pyrolysis gases made
from organics derived from trash, a small quantity of
synthetic crude oil was produced from the partially
purified gases available. This synthetic crude oil was
distilled and 93% of it boiled in the gasoline range. The
distillation curve for the polymer gasoline made from
pure ethylene was virtually identical to that for the
gasoline made from trash derived organics. The physical
appearance of the two synthetic gasolines is an identical
very pale yellow and with a gasoline odor. Although
sufficient gasoline made from pyrolysis gases has not yet
BY-PRODUCT GASES
(CO.
ch^ h2;
LEAN OIL
TO RECYCLE
OLEFINS
2S0°F
440 psiL2i£H
OIL
750
PSI
430
PSI
430
PSI
BOILING
SULFUR
THERM0SYPH0N
POLYMERIZATION
COIL
PYROLYSIS
GASES —
AT 450 PSI
KHC0
PRESSURE
BOOSTER
POLYMER
GASOLINE
STORAGE
1 ATM
CJ
KHS
Fig. 6. Purification and Polymerization Schematic
46

-------
been produced to allow an octane test to be run. it would
appear reasonable to expect it to nave an octane rating
similar to that of tne gasoline made from pure ethylene.
Additional effort needs to be expended in tne bench scale
system particularly in the areas of: low pressure
pvrolysis gas scruooing to more completely remove the
tar mists: the hydrocarbon absorption and stripping
system to verify that the reported high levels of fas
purification can be attained with gases that contain
carbon monoxide; the addition of a soaking chamber to
the polymerizing reactor to increase Che residence time
to increase the conversion per pass; the addition of a
recycle loop around the polymerizer to increase the
overall yield: the full characterization of the synthetic
gasoline and oil product: and the evaluation of feedstocks
other than trash derived organics. A modest program to
pyrolvze pure cellulose and pure lignin powders to be
able to project biomass potential for this process has just
been started with funding from the Solar Energy
Research Institute.
COMMERCIALIZATION POTENTIAL
It was noted previously that the pyrolysis conditions used
in development for organic waste are very similar to
those used to pyrolyze crude oil and naphtha to ethylene.
It follows chat once che solid wastes are fluidized by the
carrier gas stream, that the technology exists in the
petrochemical and petroleum industry to design and build
commercially-sized organic waste pyrolysis units. Since
similar compression, purification, and polymerization of
the gaseous hvdrocaroons have all been commercialized
in the past, it would appear that the process could be
contracted to any one of several petrochemical or
petroleum construction firms with a fairly low technical
risk. For pilot plant demonstration purposes, it may be
economically advantageous to add this gasoline module
to an existing trash processing plant already in operation
or to locate it in an area having several types of agri-
cultural wastes available.
PRELIMINARY ECONOMICS
Municipal Waste Feedstock
To determine the economic feasibility of the process to
convert municipal trash into gasoline requires a long list
of assumptions. For the use of municipal trash as feed-
stock it was assumed to contain 50% dry, ash free
organic material, '.3% inorganics (iron, aluminum, and
glassl. and the balance moisture. A credit of $4.35 per
tonne (54.40 per ton) of trash processed was assumed for
the value of the reclaimed metals and glass. A yield of
0.19 liters of hydrocarbon liquids per kilogram (45
gal/ton) of trash processed was assumed. The relative
economics of the process were taken to be a function of
source of capital, plant size, gasoline (hvdrocaroon)
value, and the dump fee per tonne of trash credited to
the process. The plant size can be converted to the
population served by the process by assuming a daily per
capita trash generation rate of '2.27 kg/dav (2.5
tons. 1000 daily people). The capital and operating cost
figures are based on those generated by an outside
petrochemical consultant under contract to EPA for a
100 ton per day plant during their evaluation of the
process. The consultant's cost estimate in early 1973
was 57.5 M capital costs and 51.LM annual operating cost
(exclusive of debt service). The capital costs .vere
scaled using 0.S5 as the exponential scaling factor,
whereas 0.20 was used as the labor cost factor.
As will oe illustrated, the method of financing the
construction costs has a significant impact on the
apparent economics of the process. Figure 7 snows che
economics for a plant financed at an interest rate of 3%
and a 25 year amortization. This would be fairly typical
of a municipally financed plant which could be operated
either by the municipality or by a contractor. It is seen
that with a 510/tonne dump fee credited to che plant
that a 250 tonne/day plant would produce gasoline worth
SO. 10/liter (S0.38/gallon).
!« MUNICIPAL AMORTIZATION
u.a rtQHNi inoxgamic «8COv(ky cmoit
,casoun( valu£ vurea ii/gali
Z
X
o
5
^ -10
a
-JO -
,0.21 IO.I
rooo
HJUtT S12*. rONNt /OAV
-ig, 7. Trash to Gasoline Economics with Municipal
Financing
Figure 3 has the same assumptions as before, but with
private enterprise involved at a 15^ rate of return. At a
L5% rate of return, the small '250 tonne per cav plant
with a SlO/tonne dump fee must charge about 50.20/liter
(S0.75/gallon) to meet its financial obligations. For
private enterprise, larger plant sizes are clearly
indicated. For example, at a 15°6 rate of return and the
same dump fee. a 500 tonne per day plant size is
estimated to produce gasoline valued at about $0.l3/liter
(50.50/gallon).
ZS. ?Onn£ • 0>y
Fig. 3. Trash to Gasoline Economics with Private
Financing

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The 500 tonne per day plant therefore appears to be an
economically interesting size. One of the problems in
evaluating the economics of this system is to project the
value of gasoline over the estimated 25 year life of the
plant. Figure 9 shows the rate of return on the
investment for a 500 tonne per day plant using the same
bases as before. With a S10 per tonne dump fee and a
current $0.685/gallon wholesale gasoline value, a 23%
rate of return would be realized. If the wholesale value
of gasoline were SI.00 per gallon, the projected rate of
return would be 34%.
(M.asrroNNE reclaimed metals and glass)
50
40
10
3
7.00
1.50
1 00
0.80
0.90
LOCAL WHOLfiSALl GASOLINE VALU* VGAL
Fig. 9. Rate of Return for 500 Tonne/day Trash Plant
Biomass Feedstock
The process to convert trash to gasoline is thought to be
applicable also to agricultural and silvicultural materials.
These organics could be a mixture of wastes and/or
material specifically grown for conversion to fuel. The
assumptions were modified somewhat to reflect the lack
of metal and glass recovery equipment and the lack of
these salvage products. The feedstock was assumed to
contain 90% dry, ash-free organic material. The yield of
gasoline per unit weight of organic material was assumed
to be the same as with municipal trash derived organics.
Similar economic trends are observed with the biomass
processing plants as with the trash plants, but the
economical size of the biomass plants is larger than that
of the trash plants due to the difference in feedstock
cost.
To interest private capital at a 15% rate of return, a
1000 tonne per day plant could pay $30 per tonne of
organics and charge $0.72 per gallon as can be seen in
Figure 10. Examining a 1000 tonne per day plant in more
detail, in Figure 11 it is seen that if the feedstock cost is
S30/tonne and the local wholesale gasoline value is SI.00
per gallon, the projected rate of return would be 31%.
These economic predictions for the process point out
that for the process to be able to buy the organic
feedstock, fairly large plants will need to be constructed.
However, by commercial standards these plants at the
1000 tonne/day size are in reality not very large and
would have an output of a fairly small oil refinery (less
than 2000 barrel per day). [f the 1000 tonne/day
biomass-to-gasoline plant were to be located at the
center of a biomass producing area having an assumed
annual biomass production rate of U.2 tonne/hectare (5
tons/acre), the necessary biomass could be raised within
a 10.2 km radius. Long hauling distances would not seem
to be involved with this process and the gasoline
produced would be consumed relatively locally.
16* RATE OF RETURN
-30
GASOLINE VALUE t/LITER 000
500
too
PLANT S12£. TONN6/OAV
Fig. 10. Biomass-to-Gasoline Economics with Private
Financing
60
x
c
3
c
u.
C
<
€
Z
w
O
c
«
1.90
1.00
Q.flO
0.80
LOCAL WHO LISA Li GASOLINE VALUI. I/GAL
Fig. 11. Rate of Return for 1000 tonne/c!ay Plant
SUMMARY
This process converts organic waste materials into the
basic hydrocarbon building blocks, i.e. the olefins:
ethylene, propylene, and butylene. Although these
compounds could be used as highly valued
petrochemicals, they can also be profitably converted to
a high octane, unleaded gasoline with only a small
amount of fuel and lubricating oils as the by-products.
The process utilizes a high temperature, short residence
time pyrolytic process with steam dilution to optimize
the production of the desired gaseous olefins. This
48

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process is virtually identical to that used by the oetro- 5
chemical industry to make ethylene and propylene from
crude oil. Once the gaseous olefins are produced, the
technology required to convert them into gasoline is
state-of-the-art. Experimentation on a 5 !
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EMERGING TECHNOLOGY FOR MAXIMUM CONVERSION
OF WASTE CELLULOSE TO ETHANOL FUEL
BY
Charles J. Rogers
Industrial Environmental Research Laboratory
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
ABSTRACT
The U.S. Environmental Protection Agency-New York University
scientists have been working over the past five years on continuous
processing technology for industrial-scale conversion of waste cellulose
to glucose. A continuous waste-cellulose to glucose pilot plant with a
capacity of one ton per day has been in operation for approximately two
years. The reactor device is a twin-screw extruder, selected because of
its capacity for conveying, mixing, and hydrolyzing up to 60 percent of
the cellulose values to glucose. In the past, acid hydrolysis reactor
development studies have focused primarily on the conversion of hexosan
to glucose. Agricultural residues and wood also contain a pentosan
fraction that can be hydrolyzed and fermented to ethyl alcohol. This
article reports results of a continuous acid hydrolysis development and
a discussion of a two-stage reactor development to maximize ethanol
production from carbohydrate-bearing waste.
50

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AFB COMBUSTION OF MUNICIPAL SOLID WASTE:
TEST PROGRAM RESULTS
by
L.C. Preuit, Project Scientist, Combustion Power Co.
K.S. Wilson, Project Engineer, Combustion Power Co.
ABSTRACT
Air .classified Municipal Solid Waste (MSW) was fired in an Atmospheric
Fluidized Bed Combustor at low excess air to simulate boiler conditions.
The 7 sq. ft. combustor at Combustion Power Company's energy laboratory
in Menlo Park, CA, incorporates water tubes for heat extraction and re-
cycles elutriated particles to the bed. System operation was stable while
firing processed MSW for the duration of a 300-hour test. Low excess air,
low exhaust gas emissions, and constant bed temperature demonstrated feasi-
bility of staam generation from fluidized bed combustion of MSW.
During the 300-hour test combustion efficiency averaged 99%. Excess
air was typically 44% while an average bed temperature of 1400 °F and an
average superficial gas velocity of 4.6 ft/sec were maintained. Typical
exhaust emission levels were 30 ppm SO2, 160 ppm NO^, 200 pom CO, and 25 ppm
hydrocarbons. No agglomeration of bed material or aetrimental change in
fluidization properties was experienced.
A conceptual design study of a full scale plant to be located at Stanford
University was based on process conditions from the 300-hour test. The plant
would produce 250,000 Ib/hr steam at the maximum firing rate of 1000 tons
per day (TPD) processed MSW. The average 800 TPD firing rate would utilize
approximately 1200 TPO raw MSW from surrounding communities. The Stanford
Solid Waste energy Program was aimed at development of a MSW fired fluidized
bed boiler and cogeneration plant to supply most of the energy needs of
Stanford University.
52

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INTRODUCTION
Disposal of solid waste has historically been an economic cost to
municipalities and industry. The least expensive means of disposal in
this country has traditionally been landfill for which the capital invest-
ment required is minimal. Rapidly decreasing availability of space for
landfill and rapidly increasing need for recovery of the energy value of
solid waste have generated considerable interest in'the development of
solid waste combustion technology. Mass burning incinerators, both with
and without water walls for energy recovery., have seen the greatest use
in combustion of municipal solid waste, particularly in Europe where in-
cineration of solid waste is much more common. Drawbacks of mass burning
include low process efficiency and high emissions levels. Alternative
processes include atmospheric fluidized bed (AFB) boilers, semi-suspension
fired boilers, and pyrolysis processes.
AF3 boilers offer the advantage of low N0X emissions and high combustion
efficiency in relatively compact equipment for the firing of municipal solid ¦
waste (MSW). Prior to the present testing, however, MSW combustion in an
AFB boiler had not been demonstrated. An experimental program was designed
to investigate the favorable operating regimes for a bed with steam-raising
tubes, to determine the combustion efficiency, to measure the gaseous pol-
lutants, to determine the erosion or corrosion of the tubes, and to investi-
gate the fouling of the tubes or system internals caused by the combustion
of municipal solid waste. Two 50-hour preliminary experiments were run
in order to shake down the equipment and to conduct parametric studies to
identify the most favorable operating regime for a subsequent 300-hour test.
This paper will describe the results of the experimental program and relate
those results to the economics of a full scale cogeneration facility being
considered for Stanford University.
EQUIPMENT DESCRIPTION
Testing was conducted in a 7 sq. ft. atmospheric fluidized bed combustor
at Combustion Power Company's energy laboratory. The refractory-1ined
combustor is cylindrical with an inside diameter of 3 ft. and an inside
height of 16 ft. A view port permits observation of the bed during operation.
Figure 1 diagrams the combustor facility as arranged for combustion of
processed municipal solid waste (MSW). Figures 2 and 3 show the combustor
and controls.
The combustor permits several arrangements of in-bed heat exchanger
tubes so that heat extraction can be adjusted to suit desired test conditions.
53

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Ol
4>-
GAS 81
PARTICULATE
SAMPLING
RECYCLE
CYCLONE
FLUID BED
7 FT*
FEED
CONVEYOR
MSW
SUPPLY
BURNER
AIR
AIR
HEATER

GAS
PARTICULATE
SAMPLING

RECYCLE
MATERIAL
SAMPLE
STEAM/WATER
WATER
LIQUID FUEL
MATERIAL
DRAIN &
SAMPLE
FLUIDIZING
AIR


GAS
COOLING
SECTION
u
COOLING
WATER
HI PRESSURE
AIR
EXHAUST

BAG
FILTER
h_t
ASH
Figure 1 Fluid Bed Boiler Test Facility

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Figure 2
CTU Fluidized Bed Combustor
at Combustion Power Co., Inc.
C*C GAS
I analyzes *acx
Figure 3
CTU Controls
«ESO«ATE
CONTROL	CONTROLLER
I ®uSH8urroNS	—
| OIL CONTROL
•ANEL
CTU CONTROLS £
55

-------
Primary neat extraction is through two, three, or roar horizontal water
tube bundles. These stainless steel tubes operate at low temperature to
assure test reliability. Typically, 150 psig water is heated from 200 F to
300 F. This water is flashed to atmospheric pressure and make-up water re-
duces the fsedwater temperature to 200 F. The water tube wall temperatures
are lower than those of typical boiler tubes so that temperature-related
corrosion does not occur. For the long duration test, air-cooled sample
tubes were installed in the fluid bed and in the freeboard above the bed.
These tubes were designed to duplicate boiler and superheater tube-wall
temperatures for study of erosion and corrosion. Figure 4 shows the bed
heat exchanger arrangement for the 300-hour test.
The combustor may be operated with or without recycle of elutriated
bed material. During the first parametric test the exhaust cyclone at
the combustor was arranged to discharge into a collection barrel rather than
returning collected particles to the bed. During the second parametric
test and the 300-hour test, elutriated particles were recycled back to
the bed from the cyclone. Discharge piping from the stainless steel re-
cycle cyclone premits sampling of recycle material during operation.
Exhaust gas from the recycle cyclone passes through a spray cooler
before final particulate clean-up in a baghouse. Stack discharge from the
baghouse meets .all applicable emissions regulations. Sampling ports are
provided before and after the recycle cyclone, and also in the discharge
stack from the baghouse.
Solid Waste Processing and Feed
Municipal solid waste is received in conventional packer trucks, each
containing 3 to o tons of refuse. The trucks dump their contents on a
covered concrete pad from which the refuse is pushed unto shredder input
conveyors as shown in Figure 5. The 100 hp Eidal mini-mill shredder has a
nominal capacity of 5 tons per hour. Shredded solid waste is air-
classified and the light fraction pneumatically transported to a storage shed
to await transport to the combustor facility.
At the combustor a live bottom bin provides short term storage and
variable outfeed capability. Processed MSW is carried from the bin by
the feed conveyor which is designed to provide uniform volumetric flow of
fuel. The' combustor bed temperature control loop adjusts the speed of the
feed conveyor, which discharges into a constant-speed rotary airlock. From-
the airlock fuel is fed pneumatically through a 3-inch feed pipe to the fluid
bed combustor.
Instrumentation
During combustion of processed MSW, temperatures in the system are
monitored at 37 points. Data is collected for pressure and flow of combustion
air, exhaust gas, cooling air and water, ana fuel oil. Exhaust gas compo-
sition is continuously monitored and concentrations of 0?, CO, NOx, and
hydrocarbons are recorded. Gas analysis is supplemented by Orsat testing
56

-------
VERTICAL TUBE(315°)
HORIZONTAL
TUBES
BED TU8E LOCATION
AIR OUTLET
WATER OUTLET
AIR INLET
(CORROSION SPECIMENS
WATER FLOW SCHEMATIC (HORIZONTAL TU8ES)
WATER
INLET
Figure
SSWEP 300 HOUR TEST
BED HEAT EXCHANGER ARRANGEMENT
57
30-1760

-------
PNEUMATIC
TRANSPORT
•SOLID WASTE RECEIVING
CONVEYORS
LOAOER
SHREDOER
INPUT CONVEYOR
¦.... SOLID WASTE
-REJECT
•' FRACTION „
- CONVEYOR •
3LOWER'
OUTFEED
CONVEYOR
AIR CLASSIFIER^
Figure 5 Solid Waste Processing Station
58

-------
at frequent intervals. Samples are taken daily for determination of HC1
concentration and particulate loading. Material samples for analysis are
taken daily from the bed and from the baghouse.
PARAMETRIC TESTS
Two 50-hour parametric tests were conducted to accomplish operational
checkout of the system, explore the range of allowable process parameters,
ana identify the most desireaole conditions for longer duration steady-state
operation. 3oth parametric tests were planned to explore the same range of
parameters. However, the first test was run without recycle while in the
second parametric test elutriated material was recycled back to the bed.
The first test ran 48 hours before being shut down by high pressures caused
by slag build-up in the combustor freeboard and exhaust duct. The second
parametric test was terminated after 73 hours of operation.
Parametric Test Results
Parametric testing began with the bed depth maintained at 2.5 ft.
(slumped), but freeboard combustion and temperatures were found to decrease
considerably when bed depth was increased to 3 ft. (slumped). Deeper beds
were used for all subsequent testing. Stable bed combustion was maintained
within the ranges of:
Sed Temperature	1300 - 1410 op
Superficial Velocity	4.1 - 6.8 ft/sec
Excess Air1	50 - 74%
2
Combustion efficiency averaged 98.9%. Operation outside these ranges,
particularly-with excess air below 40% resulted in undesireable freeboard
^Excess air is calculated from:
EA = 2.67C +~3H + S - 0 X C02 +°C0 X 1C0?°
where: EA = Excess Air
C, H, S, 0 = Respective Elemental dry weight %
02, CO2. CO = Respective gaseous dry volume %
^Combustion efficiency is based on unburned carbon in the flue gas and ash:
M" a(6HC02^ + if b^HC0^ + ft c^AHh'C^
12 _ . 12 . .~7
-------
afterburning and slag deposits in the combustor freeboard and exhaust ducting.
The 3-inch diameter fuel feed line was found to be very susceptible to
plugging problems caused by round plastic lids of approximately 4-inch
diameter. These' lids were resilient enough to pass through the shredder,
light enough to pass through the air classifier, but just stiff enough to
cause blockage of the pneumatic feed line. Adjustment of the air classifier
eliminated most of the lids and the problem with feedline plugging, but also
resulted in rejection of a larger proportion (near 50°.:) of the shredded MSW
than had been desired. Larger diameter feedlines or improved shredding of
the MSW would eliminate this problem in large scale equipment.
Slag deposits which formed during parametric tests were subjected to
fusion-temperature analysis and found to have initial deformation tempera-
tures of 1990 f and above. Differential thermal analysis confirmed the
fusion test results. Since slag formation thus appeared to be related to
high freeboard temperatures, one process condition set for the 300-nour
test was a freeboard high temperature limit of 1600 F. The slag samples,
analyzed were, in general, calcium-rich alumina silicates.
300-HOUR TEST
Operating conditions for the 300-hour test were based on results- of the
two parametric tests. Test objectives were to:
•	Demonstrate the feasibility of burning municipal solid waste
in an atmospheric fluid bed combustor with energy extraction
from the bed.
•	Evaluate the fluid bed media and fluiaization characteristics
over a 300-hour time period.
•	Characterize exhaust gas emissions
•	Measure bed heat transfer coefficients
•	' Gather data on erosion and corrosion of typical boiler and
superheater materials at representative tube wall temperatures.
The 310 hours of operation included 298 hours firing MSW at test conditions.
The test was completed without any significant combustion-related problems,
and operating conditions remained substantially constant. Upsets were
caused by feedline plugs which occurred 35 times during the test. These
blockages, caused by plastic lids which did not shred during fuel processingn
were cleared within 2 to 5 minutes while combustor operation was maintained
on oil. No material deposition or agglomeration was observed; at test
conclusion the combustor and freeboard were virtually free of slag.
60

-------
Fuel Analysis
Samples of the processed MSW were analyzed daily. Fuel properties
were reasonably consistent throughout the test. Results of proximate and
ultimata analysis on the fuel are:
PROXIMATE ANALYSIS
(As Received)
Averaae
Ranae
Moisture Fraction (%)
23.5
17 - 26
Ash Fraction (%)
lO.c
9 - 13
Volatiles {%)
57.5
54 - 54
Fixed Carbon (")
8.2
8 - 9.7
Higher Heating Value (Btu/lb)
5572
5250 - 5050
ULTIMATE ANALYSIS
(Dry Weight %)
Average
Ranae

Carbon
44.46
43.9 -
45.2
Hydrogen
5.96
5.8 -
6.1
Oxygen
34.32
32.2 -
35.6
Hi trogen
0.67
.53
- .80
Chlorine
0.49
.40
- .67
Sulfur
0.13
.09
- . 17
Ash
13.97
12.0 -
16.0
Higher Heating Value (Btu/lb)
7352
6900 -
7700
Operating Conditions
Operating conditions remained substantially constant throughout the
300 hours of test operation although some parameters changed due to a gradual
decrease in bed particle size that occurred during the first half of the test.
As typical steady state operating conditions, data from the last 144 hours
of the test were averaged:
Sea temperature
1392
o_
r
Freeboard temperature
1437
°F
Superficial velocity
4.6
ft/sec
Excess air
44
Of
•'0
Bed depth (slumped, nominal]
3.5
feet
Fluidizing air flow
43.0
1b/mi n
Fuel feed rata
8.2
1b/min
Combustion efficiency
99.0
a'
j:
Exhaust material recycle rate
16
1b/mi n
Sachouse ash collection rate
0.9
1b/mi n
3ed material letdown rate
4.9
1b/hour
61

-------
Figure 6 shows the temperature recorder chart for a portion of the twelfth
day of operation (259 through 256 hours into the test) as representative of
general test conditions. 3ed temperature remains constant, despite fluctua-
tions in freeboard and exhaust temperatures caused by variations in heating
value of the processed MSW fuel. Note that sample time periods for emissions
and gas analysis are identified and that, during two hours of the recorded
period, gas analysis data were being recorded by the California Air
Resources Board (CARB) using their mobile equipment. Satisfactory agree-
ment was found between CARB and C?C data for gaseous emissions.
Flue Gas Emissions
Emissions levels in the flue gas were considered very important to the
basic program objective of demonstrating the feasibility of steam generation
by firing MSW in an AFB boiler. Actual emission levels verified the potential
for low flue gas emissions levels. Average emissions levels for the last 144
hours of test operation were:
Generally, each of the gaseous constituents monitored tended to exhibit
constant variation. Occasional very high spikes of SOj, CO, and hydrocarbons
occurred independently of each other or any other parameter recorded. These
spikes were probably due to particular constituents of the MSW fuel. Emissions
of SO2 and N0X are of particular concern in light of the tight regulations
regarding these pollutants. Actual emissions levels were well under 1979
EPA promulgated New Source Performance Standards (NSPS) for boilers but would
require emissions offset consideration to be approved by California and
local authorities. The indicated exhaust concentrations translate to approx-
imately 0.06 Ib/MMBtu fuel input for SO2 and 0.25 lb/MMBtu for N0X average
for the last 144 hours of operation.
Bed Material
The original bed material was Monterey 16-mesh sand with an average
particle size^ between 1.0 and 1.1 mm. Daily samples were taken of bed
material and of material returning to the bed from the recycle cyclone.
Figure 7 shows the rapid drop in bed particle size at the beginning of the
^Particle size is calculated by the "Mean Specific Surface" method (1)
Flue' Gas Emissions
02
5.7 %
13.5 %
200	ppm
29	ppm
160	ppm
40	ppm
Hydrocarbons (as CH4)
62

-------
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SSWEP NO. 3 TEST
AUGUST 29, 1979 j
259 THRU 266 HOURS FROM

:
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-------
1.0
ON
-C-
E
E
Hi
M
ci
IU
-J
U
tc
<
a.
IU
0
1
EC
(U
>
<
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
* lici.yi.je.
Mean Specific Area
• Be J Material,
Mean Specific Area
	1	1	I	I	I	_l	I	I	I
6 7 a 9 10 11 12 13 14
CALENDAR DAY
Figure 7

-------
test, followed by a more gradual decline to nearly constant particle size
at the end of the test. Also shown is the recycled material size which
appeared unaffected by the changing bed material size. Some pieces of glass
could be observed in the material samples and a few (less than 1%) pieces
of agglomerated particles up to h" size.
Daily bed material samples were analyzed for cations and metals content
by means of the emission spectroscopy scan method. The concentrations of
the major constituents of the bed material were found to remain essentially
constant. A number of elemental concentrations, however, increased through-
out the test and accumulation of these materials appeared to be continuing
up to the time the test was terminated. This accumulation of elements was
the only observed phenomena which had not reached a steady state equilibrium
before the end of the test. Longer test duration will be necessary to observe
the effects of this accumulation. Elements which accumulated were Ca, Fe,
Mg, Ti, Na, Cu, Mn, P, Zn, and possibly Pb. Concentrations of these elements
are shown for samples taken early in the test and at the end of the test
(Trace elements are not shown):
Concentration Weight %
Element
Third Day
Twelfth Day
Si
37.0
33.8
A1
4.0
3.8
Ca
1.8
5.5
K
2.8
2.7
Na
1.9
4.0
Fe
0.48
1.2
Mg
0.17
0.69
Ti
0.068
0.28
Ba
0.11
0.10
Heat Transfer
Water inlet and outlet temperatures as well as flow through the main
heat exchanger were monitored throughout the test. That heat exchanger con-
isted of two four-pass, horizontal tubes arranged in the bed as shown in
Figure 4. Early in the test, the overall heat transfer coefficient averaged
46 3tu/nr-ft--F. 3y the end of the test, the heat transfer coefficient had
increased to 58 3tu/iir-ft2-F. The increase in heat transfer coefficient is
attributed to the decrease in bed material particle size. The influence of
particle size on outside wall heat transfer coefficient is predicted by
Bashakov {I) or Locke (3_).
Corrosion and Erosion
In addition to the stainless steel (TP316H) water cooled tubes in the
bed which were the primary means of heat extraction, air cooled sample
tubes were installed in the bed and in the freeboard to duplicate wall
65

-------
temperatures of superheater tubes. No significant corrosion or erosion
was observed on the water cooled tubes in the bed. Mechanical failure of
the air cooled tube in the bed invalidate its exposure as a tube sample.
The freeboard air cooled sample tube was installed to transverse gas
flow in the exhaust ductwork from the combustor. The tube was fabricated
from sample sections of six different tube materials. The samples were
exposed to 1500 F - 1600 F flue gases heavily laden with particulate
(40-50 gr/acf) at a gas velocity of about 35 fps. The sample tube wall
temperature was about 720 F. Combined corrosion and erosion resulted in
substantial metal wastage of carbon steel specimens, with less wastage
apparent as the alloy content increased.
As shown in Figure 8 and Table I, metal wastage was greatest for carbon
steel coupons, approximately 50-60% of the wall facing the gas side, while
wastage of the sides and tops was less than 5«. Wastage was considerably
less for the low alloy steels in the same orientation. On the side facing
the gas flow, the wastage was 13-172 while elsewhere it was less than 3%.
The metal wastage of the austenitic specimens (SS304, SS316, and Incoloy 825)
was the lowest, being less than 6% on the side facing the gas flow and less
than 1% elsewhere. Scaling and deposits were also orientation dependent,
with bottoms of the coupons relatively free of scale and deposits compared
to the sides and top. As expected, scale formation was thickest on the
carbon steels, and the chrome-containing austenitic steels were resistant
to scaling.
Residual corrosion penetration was very low on the bottoms of the
carbon steel and low alloy specimens. Apparently, corroded areas and scale
were removed by erosion as they formed, i.e., corrosion-erosion was a
major factor in the metal wastage. Corrosion penetration on the low alloy
specimens was comparatively low on the tops and sides at 5 - 10 microns.
With respect to corrosion under the exposure conditions, the low alloy
specimens compared well with the type SS316 that showed only 5-10 microns
of corrosion penetration, while the metal wastage of the low alloy specimens
was greater. The SS304 and Incoloy 825 showed corrosion penetrations ranging
from 10-50 microns. Apparently, corrosion was by oxidation and sulfidation
as sulfur was found in most corroded regions of all coupons.
CONCEPTUAL DESIGN STUDY
An economic study was undertaken to determine the promise of the AF3
boiler system as defined by the results of the experiments. The complete
coaeneration system was envisaged for application to the Stanford University
campus with the sizing and performance of the MSW fired AF3 boiler based on
test results. While the application at Stanford University might not have
been the most favorable one, it was regarded as a typical situation and that
there would be considerable benefit in having a study made to meet realistic
reaui rements.
66

-------
GAS FLOW
SPECIMEN
IDENTIFICATION
7A7
Nfc^Cr-Mo-Cu
INCO 325
St>163
6A6
16Cr-12Ni-2Mo
SA-312-TP316H
SA-213-TP-316H
5A5
18Cf-3Ni
SA-312-TP304H
SA-213-TP-304H
4A4
2'
-------
TOP
SSWEP: 300 MR TEST COUPONS
. LOCATION: CTU FREEBOARD
TABLE I PIPE THICKNESS ANO MICROGRAPH MEASUREMENTS
GAS STREAM





(Residual Maximum]

Specimen

Pipe Thickness

Micrograph

Pipe
(Inch)
V
3
Measurements



S


ica le
Penetra-
Garments
Identification
Orientation
Unexposed
Exposed
wastage

tion M

IA1
1. Bottom
.115
.060
47.3
None(a)
6
(a) Corrosion-







erosion
(Carbon 5tee!)
2. Left
.112
.113
-.9
15
10


Side






(SA-106B)
3. Top
.110
.116
-5.5
16
60

(SA-210AI)
¦4. Ri gh t
.113
.110
2.7
(b)
14
(b) Spalled

Side






3A3
1 .
.116
.100
13.3
3
<2

(1 !iCr-4 Ho-Sr)
2.
.115
.116
-.9
cG
10

(SA-335P11)
3.
.118
.124
-5.1
15
10

(SA-213T11)
4.
.120
.117
2.5
250(a)
1G
(a) Scale and







ash de-







posit
4A4
1.
.135
.113
16.3
30
<2

(2>sCr-l Mo)
2-
.130
.125
.3
a.
5
a. Spa lied
(SA-335P22)
3
.129
.131
-1.5
b.
10
b. Spa lied
(SA-213T22)
4.
.132
.132
0
c.
5
c. Soalled
5A5
1.
.105
.100
4.3
-
35
.005" wastage
(18Cr-3Ni)
2.
.105
.105
0
100(a)
50
(a) Scale ana







ash de-







posit
(SA-312-TP304H)
3.
.105
.106
-1.0
(b)
10
(b) Spa 1 led
(SA-213-TP-304H)
d.
.104
.104
0
200(c)
10
(c) Scale and






ash da-







DOS i t
6A6
1
.107
.101
5.5
3
-
.006" wastage
{16Cr-l 2Ni -2Mo)
12
.118
.113
0
30
10

(SA-312-TP316H)
! 3
.107
. 107
0
a.
-
a. Spa 1Tad
(AS-213-TP-316H)
4
.106 '
.106
0
b.
5
b. Soalled
7A7
1
.112
.109
2.7
20
30
.003" wastage
(Ni-Fe-Cr-Mo-Cu)
2
.113
.113
0
a.
30
a. Spa 11ed ?
(INCO 325)
3
.117
.117
0
b.
4
b. Spalled ?
CSb-163)
4
.118
.119
-.3
c.
25
c. Ash cie-






30S i t
Unexposed pipe remnant measurements.
68

-------
Proposed System
The AFB system for study was designed to meet an existing situation
in which the local municipality is faced with unavailability of landfill
disposal area while Stanford University is seeking to control energy costs.
Municipal solid wast? would be processed at a central collection location
and the MSW fuel trucked to the campus boiler plant. Size of the system
is specified by the 800 tons per day of processed MSW estimated to be
available in 1983. The modular AF3 boilers would produce 600 psia, 750 F
steam for a turbine with extraction at a pressure of approximately 170 psia.
The extraction steam would condense in a heat exchanger to provide heating
and chilling steam for the campus, Steam not needed for caucus services
would flow through the condensing stage of the turbine. Thermodynamic ana
process studies provided estimates that the proposed system would supply
all of the university steam demand and approximately 50* of the electricity
needs.
A flow-diagram of the proposed system is shown in Figure 9. No attempt
was made to investigate the. processing of the MSW; study was limi-ted entirely
to conversion of the processed MSW to thermal energy and to electricity. All
ancilliary equipment necessary for energy production from MSW fuel was in-
cluded.
Plant Design and Cost Estimating
The plant design was broken down into 12 major components listed below:
1.
Boiler system
2.
Start-up system
3.
Combustion air system
4.
Flue gas system
5.
Bed-maintenance system
5.
Flyash-disposal system
7.
Fuel-feed system
a.
Fuel receiving and storage
g.
Main steam system
10.
Feed-water system
11.
Electrical and control system
12.
Buildings and site
For each of these systems, sufficient design work was done to define a concept
ana to specify the necessary size of the equipment. Wherever possible,
standard components were used and cost estimates obtained from vendors. A
plant plan, Figure 10, and laycut drawings were made and necessary buildings
included to enclose turbine, boiler, and fuel receiving areas so as to be
compatible with the campus site. No cost was included for the value of the
land. Table il lists the major cost components along with the principal
items contr*butino to the cost. An artist's rendition of what the plant
might look like is shown in Figure 11 and general performance figures for
the plant are shown in Table III.
69

-------
lUHblNt
fcXFHACIiON
irAfifc
CONDENSING
ilACt
iltClHlCAL
COnOCNSATC
ihom s.u.
tXCilANGtH
rtCDWAI tH
O
PMlMARV tXllAUSI
ClEANUP
INDUCED OflAf I
fcKMAUSTCA&
\7
TIMPOHAHY
JIOHAGE AHiA
^~L
o o oo
fCfOtVAIEH
OO
COMUUSTOa
ASH
Aifl
fcOliO WA<
fiiU CONVfYOHS
COUUUSUON
AIR OLOM£A
fE£0 ttUJWtKS
ilTDOMM	MAKCUf
Figure 9 Stanford Solid Waste Energy Plant Flow Diagram

-------
310
-CZO] E==
TURBINE BLDG.
FUEL RECEIVING BLOG.
BOILER BUILDING
ASH SILO
SAND SILO
COOLING TOWERS
RESERVE FUEL
TANK
Figure 10
SITE PLAN
STANFORD SOLID WASTE ENERGY PLANT

-------
Hoi lor System
Modules w/tubes & plenums
Itecyc Lc cyclones (2^>)
Exhaust manifolds (2)
Evaporators (2)
Economizers (2)
Attomporacors (2)
S111»jioitii & lagging
Scolli lowers (6)
Start-up System
Duct-burner assembly
llooster fan
Fuel-oil pumps (dual)
Fuel-oil storage tank
lied Injectors (36)
Air manifold & dampers
Combust Ion Air System
F.I). fans 4 motors (2)
InLake silencers (2)
Tubular air preheaters (2)
Dm: twork
I I iiij-C.'ns System
M
-------
Table III
PLANT PERFORMANCE
•	Design Firing Rate for Processed MSI.1 Fuel:
Average - 800 tons per day
Maximum - 1000 tons per day
•	Yearly Average Plant Output
Steam at 125 psi, 110,800 Ib/hr
Electricity -6.7 MW
i Soiler Output: Steam at 600 F, 750 psi
Average - 200,000 Ib/hr
Maximum - 250,000 Ib/hr
t Maximum Electrical Output (net)	13.8 MW
Concurrent 125 psi steam output	91,200 Ib/hr
•	Fuel Storage: Normal:	200 tons (6 hrs average output)
Maximum:	500 tons (15 hrs average output)
•	Reserve Fuel: Low-grade bunker oil - 35 GPM at maximum output
t Reserve Fuel Storage: 126,000 gal, 3 clays
73

-------
BOILER BUILDING
TURBINE BUILDING
STANFORD SOLID WASTE ENERGY PLANT
STEAM	- 250.000 LBS/HR MAXIMUM
ELECTRICITY - 13.8 MEGAWATTS MAXIMUM
WASTE FUEL	800 TONS PER DAY AVERAGE
FUEL RECEIVING BUILDING


-------
Environmental Considerations
Emissions data collected during the 300-nour test were converted to a
pounds per hour basis using the flow rate of combustion products for an 800
tons per day plant. Below are the data reported in this form, together
with the "offset" that Stanford is permitted to take if it shuts down its
present oil-fired heating plant.
Emission	Projected 800-TPD Plant Offset from Existing Plant
Only CO would exceed the offset available from the existing boiler. The
present boiler figures are based on steam generation at the rate of 80,000 Ib/hr
whereas the AF3 plant figures are based on 800' tons per day fuel corresponding
to 110,000 lb/hr of steam plus' an average of 6.7 MW of electrical power. Thus
the AF3 boiler is nearly 40« larger than the present boiler and the emission
levels are very similar. It appears that fluidized bed combusitan of MSW
is a sufficiently clean process that there would be little difficulty in
meeting the stringent requirements of the San Francisco Bay Area Air Pollution
Control District when the offset from the present boiler is considered.
Economic Summary
Cost estimates for the proposed full scale system are summarized in
Table IV. Each major subsystem is shown, along with the additional costs
which are recommended for a construction project such as this by the standards
of the Electrical Power Research Institute. The total direct cost as esti-
mated is 16.7 million dollars, and the total plant investment, using various
contingencies and sales tax, amounts to 23.1 million. This figure should
be compared to plants which handle 1200 tons per day of raw municipal solid
waste and produce both steam ana electrical power. The costs presented do
not include processing or transporting the processed MSW to the point of use.
CONCLUSIONS
Successful completion of the 300-hour test demonstrated the feasibility
of fluidized bed combustion of municipal solid waste to generate steam.
Necessary conditions for steam generation were met:
1.	Operation at reasonably low excess air (44%) for porcess efficiency.
2.	Constant bed temperature (±20 F) for controllable system output.
3.	Freedom from slag and its associated problems.
4.	Low exhaust gas emissions for environ-enta1 acceptabi1ity.
2.9 lb/hr
24.1 lb/hr
Hydrocarbons
7.7
8.9
0.7
23.1
5.2
1.1
75

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Table IV
STAFFORD SOL I 0-'.'ASTE ETIERGY PLANT
Total plant investment
1.	3oiler system	S 2,239,700
2.	Startup system	155,200
3.	Cornbustion air system	793 ,900
4.	Flue-gas system	2,382,000
5.	3ed-i-aintenance system	34,100
6.	Flyash-disposal system	79,200
7.	Fuel-feed system	457,300
3. Fuel-receiving bldg., equipment	252,400
9. Main steam system	5,421,000
10.	Feedv.-ater system	1,942,500
11.	Electrical/control s/misc.	1,204,100
12.	3uilding, sitework, construction, A S :		1 ,545 ,000
Total Oirect Costs	16,552,000
Undistributed Costs (6")		999,700
Process Capital	17,551,700
Engineering ¦£ Heme Office Fees		1,555 ,700
Subtotal	19,327,900
Project Contingency (Subtotal x 15.")	2,339,200
Process Contingency (Item 1 x z%)	112,000
Sales Tax		777 ,300
Total Plan: Invest-ant	23,115,-00
76

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These conditions were met in a long-duration test designed to reveal any
process problems likely to develop.
Bed material characteristics after long term operation will depend on
the source and preparation of the solid waste fuel. Early in the 300-hour
test the average bed particle size decreased significantly although it
subsequently appeared to reach equilibrium. The elemental composition of
the bed was still changing after 300 hours. Neither situation caused any
detrimental change in bed fluidization properties nor were emissions
affected. It was concluded that the overall heat transfer coefficient for
the bed tubes increased due to to the decrease in bed material size.
Sample tubes exposed to a high velocity flue gas stream with	high
particulate loading experienced substantial metal wastage. Alloy	steels
would be suitable for service if protected from abrasion but none	of the
samples tested would be suitable for long term service under test	conditions.
Conveying air in the .fuel feedline constitutes a significant (30")
portion of the total combustion and fluidizing air. This air enters the
bed as a point source and is not easily distributed throughout the bed.
While a larger feedline is desireable to avoid feedline plugging and permit
firing of more coarse fuel, greater spacing between larger feedlines may
create air distribution problems in the bed. Investigation of alternate
fuel feed technology is warranted.
Based on data from 300 hours of testing, projected emissions from an
AF5 boiler firing municipal solid waste would be low compared to a existing
conventional oil fired boiler. Total plant investment for a coaeneration
plant burning 800 tons per day of processed MSW fuel would be S23,115.000,
corresponding to approximately SI,150/kw if the entire steam output were
converted to electricity.
77

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ACKNOWLEDGEMENT
This work was accomplished at Combustion Power Company, Inc. under
sub-contract to Stanford University with the program jointly sponsored
by the United States Environmental Protection Agency and Department of
Energy. The generous contribution of Professor R.H. Eustis of Stanford
University is gratefully acknowledged.
78

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REFERENCES
1.	Kunii, 0., and Levenspiel, 0., "F1uidization Engineering", John Wiley
and Sons, 1979.
2.	Bashakov et.al., (1973). Powder Technology, pp. 8, 273.
3.	Locke, M.S. et al, "Fluidized Combustion in Great Britain", paper
presented at Fourth International Conference on Fluidized Bed Combustion,
Mitre Corporation, McLean, Virgina, December 1975.
4.	Vander Molen, R.H., "Fluidized- Bed Combustion of Solid Wastes", Presented
at the Symposium on Thermal Conversion of Solid Waste and Biomass,
American Chemical Society Meeting, September 1979, Washington, D.C.
79

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EVALUATION OF THE AMES SOLID WASTE RECOVERY SYSTEM
Joensen, A.W.
Hall, J.L.
Even, J.
Van Meter, D.
Adams. S.K.
Gheresus, P.
Engineering Research Institute, Iowa State University, Ames, Iowa 50011
EPA CONFERENCE
WASTE TO ENERGY TECHNOLOGY UPDATE
Cincinnati, Ohio
April 15-16, 1980
80

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INTRODUCTION
The Cicy of Ames, Iowa has been commercially operating a Solid Waste
Recovery System since November, 1975. This system processes municipal and
commercial solid wasce Co recover refuse derived fuel (RDF) and ferrous
mecals. This solid waste recovery system consists of chree major subsys-
tems; a nominal 150 ton/day process plane, the 500 con Adas storage bin
and che chree coal fired steam generators at che existing municipal power
plant.
Conceptual design for che system operacion specified burning RDF with
coal in a 35 MW tangencially fired pulverized coal fired boiler (unit Mo.
7) at firing races up to 207. or 8 cons/hour. Initial operation in October
1975 resulted in a high dropout of unourned material into che boccom ash
hopper. The power plane chen began burning RDF with coal in che 7.5 MW or
che 12.5 MW spreader stoker boilers. The problem of high unourned material
dropouc in che 35 MW unic was solved by che inscallacion of a Combustion
Engineering Company dump grace at che furnace boccom. This modification
was completed by May 1, 1978, and RDF has been successfully burned in this
unit since chat time.
A three year evaluation of Che Ames Solid Waste Recovery System was
funded by che Environmental Protection Agency and che Department of Energy
with addicional support provided by Iowa SCate Universicy and che American
Public Power Association. Detailed resulcs of che scoker performance and
process plant operacions have been reporced previously [1,3,^,5,9].
Resulcs of che unic No. 7 emissions evaluation is given in [3] while the
total system study for year III is given in [7]. The inability of che
process pianc to initially remove ground glass and other fines resulted in
extreme erosive wear at che process plane, Atlas bin and all of the pneu-
matic cransport lines and in boiler slagging. This problem was solved by
the installation of a double set of a disc screen fines removal syscem in
October-December 1978. This modification and some process plane operacional
resulcs are discussed in (2,7].
This paper presencs some important results obtained from this chree
year syscem evaluation.
PROCESS PLAiNT
A derailed descripcion of che process plant is given in [1,2,5,7].
The material processed and materials recovered are listed in Table 1. The
improvement in RDF quality due to che disc screen inscallacion is shown in
Table 2. Nec coses per con for 1976, 1977 ana 1973 were S1&.27, Sll.ii
and S11.31 respectively.
RDF ana mecai sales for 1978 constituted 7^.37% and 13.53% of cocal
income. Electric energy consumption for 1978 is 63.17 khr/'ton.
31

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POWER PLANT
Stoker Fired Boilers No. 5 and Mo. 6
Selected emissions from boilers No. 5 and 6 are listed in Tables 3 and
4. The coal contained a large number of fines which resulted in high parti-
culate emissions. After the installation of new mechanical collectors in
July 1979, along with cutting out of reinjection backpass fines and the
increase of front overfire air, subsequent private tests indicated the
reduction of stack particulate on coal only and coal plus RDF firing. This
latter result was also due to the disc screen installation.
Pulverized Coal Fired Unit No. 7
The installation of the dump grate resulted in the successful burning
of RDF with coal. Selected emissions are listed in Table 5.
Combustion air to the furnace is supplied by secondary air from the
air heater discharge, primary air from the pulverizer, cold undergrate air
supplied from a separate fan, and cold overgrate air entering at each end
through open observation doors, and the two diagonally opposed RDF transport
lines which supply 1.67 m^/sec (3539 ft^/min) of cold air through the air-
lock feeder at the Atlas bin. Undergrate air was 1.70 mVsec (3603 ft^/min)
and overgrate air flow was 0.94 m^/sec (2000 ft^/min).
Excess air at 80% steam load (based	on fuel ultimate analysis) varied
from 41.9% for coal only firing to 41.7%	at 20% RDF nominal heat input.
At 100% steam load the excess air varied	from 42.5% for coal only to 34.6%
at 20% RDF heat input firing.
At 80% steam load, the boiler efficiency decreased linearly from
84.4% (ASME Heat Loss Method) at 0% RDF to 81.1% at 20% RDF firing and
these efficiencies include a manufacturer 1-1/2% unaccountable loss. The
air heater outlet flue gas cemperature increased from 181.1"C to 422aF.
At 100% steam load, the boiler efficiency decreased from 84.35% at
0% RDF to 83.02% at 20% RDF firing. The air heater outlec flue gas temper-
ature increased from 191.7°C to 198.9°C.
At 80% steam load the bottom ash flow rate varied from 64 kg/hr at 0%
RDF to 218 kg/hr at 20% RDF input. At 100% steam load, the bottom ash
varied from 134 kg/hr at 0% RDF to 821 kg/hr at 20% RDF input. Likewise,
the percent heat loss in bottom ash never exceeded 0.2%.
Thus, the installation of the bottom dump grates in the 35 MW pulver-
ized coal boiler allowed for the successful burning of RDF with coal.
ACKNOWLEDGMENTS
The summary data presented above were obtained from a research project
performed by the Engineering Research Institute of Iowa State University
through funds provided by IERL/EPA, Cincinnati, Ohio. Analysis of labora-
tory samples collected was performed by the Ames Laboratory/DOE through
support by the DOE. Technical support and assistance was provided by the
Midwest Research Institute. The generous support of the City of Ames is
also greatly appreciated.
82

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Table 1. Refuse Processed and Materials Recovery
Year
Raw Refuse
RDF3
Metals
Rej ects
Ocher Material

Processed
Produced
Recovery



(Mg)
(")
(7.)
(%)
(Z)
1976
37,252
84.2
7.00
7.5
1.30
1977
44,027
34.54
6.22
8.87
0.39
1978
34,216
84.26
6.31
9.39
0.04
a3y mass difference
Table 2. RDF Characceriscics 3efore and Afcer Disc Screen Installation
RDFa

Before
After
Higher Heating Value - 3TTJ/lb
4904.9
6103.3
(kJ/kg)
(11,408.7)
(14,209.1)
Proximate and Ultimate Analysis, 7.


Ash
20.99
9.55
Moisture
22.06
13.42
Fixed Carbon
30.79
56.10
Volatile Matter
26.16
15.93
Carbon
00
ui
36.67
Hydrogen
6.35
7.42
Nitrogen
0.39
0. 34
Oxygen
42.75
45.62
Sulfur
0.34
0.19
Chloride
0.23
0.21
"Comparative Sampling Period Jan--Mar
83

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T.ihi c ). SKMiCTKD EMISSIONS FROM HOILF.K UNIT 5
Parameter (units)
Particulates (controlled)	(g/MJ)
p.-rticulates (uncontrolled) (g/MJ)
Oxides of sulfur, S0X	(g/MJ)
Oxides of nitrogen, NOx	(ing/MJ)
Chlorides	(ing/MJ)
Fo rma 1 de y hde	(mg/MJ)
Hydrocarbons	(ing/MJ)
80% load
1976 Iowa coal with
OX RDF	20Z RDF 50% RDF
807. load
1977 lowa/Wyoming coal with
07. UDF	201 RDF 50X RUf
0.7 i 0.5	0.4 i 0.0	0.3+0.1
3.6i0.6	4.110.2 3-410.2
2.3 l 0.0	1.9 1 0.2 1.5 i 0.6
80.0 ±25-0	76.0 t10.0	64.0 +17-0
13-0 ± 3-0	68-0 i 8.0	97.0 143.O
0.2 t 0.3	0.2 t 0.1 4:3 1 4.1
0.221 0.13	0.171 0.07 0.191 0.08 0.081 0.06 0.09* 0.04 0.071 0.03
O.fl 10.2	0.910.1	1.0 1 0.2
3.2 1 0.5	3.8 1 0.3	4 .2 l 0.9
1.0 i 0.3	0.7 1 0.2	0.9 i 0.4
77.0 1 6.0 67.0 1 6.0 69.0 il3-0
6.5 i 0.7	87-0 121.0 139-0 142.0
11.7 118.2	3.7 11.9	3.4i3.1
Parameter (units)
60% load
1976 Iowa coal with
07. RDF	20% RDF	SO'/. RDF
Particulates (controlled) (g/MJ)
Particulates (uncontrolled) (g/MJ)
Oxides of sulfur, SO
Oxides of nitrogen,
Chi or ides
Forma 1 deliyde
Hyd roc a rlions
x
NO.
(g/MJ)
(mg/MJ)
(mg/MJ)
(mg/MJ)
(mg/MJ)
0.9 i 0.5
3.2	1 0.5
1.3	i 1.0
99.0 112.0
22.0 <12.0
2.7 l 2.7
0.151 0.08
1.1 l 0.6
4.4 l 0.6
2.3 1 0.5
104.0 1 8.0
58.0 H7.0
3.1 1 3.3
0.191 0.08
1007. load
19 76 Iowa coal with
OX RDF	207. RDF
505: RDF^V
1..3 1 0.7
3.5 l 1.4
0.8 1 0.4
78.0 120.0
100.0 155.0
6.2 1-8.1
0.311 0.12
1.3	1 0.9
4.1 1 1.1
2.4	i 0.0
81.0 117.0
7.0 l 0.0
3.3 1 3.6
0.09l 0.06
0.4 1 0.I
2.2 1 0.8
2.0 1 0.3
76.0 117.0
62.0 i22.0
2.0 1 2.8
0.151 0.06
^]y
0.4 i
3.1
1 . 7
50.0
101 .0
0.2
0.17
0. 1
1 . 3
0.3
8.0
21 .0
0.1
0.01
two runs at this load and % RDF were accomplished.

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¦Vul.le A. SKI.liCTtll I-IHISSIONS FKOM HOII.IX UNI T 6
I'ai ameter (unite)
Pari iinlaleb (nun hi 1 I ed )
I'n r i 1 cu 1 a t ts (uncont ro I 1 ed)
Oxides of sulfur, S0X
Oxides of a 11.rugeii, ll(lx
f'li lor ides
Fo r ma I <1 e It yd e
11 y <11' oca r lioiku
BOX load
1976 1 oua/l'yoin I ng coal wlt:l»
OX HOF 201 RDF 501 HDF
BOX load
(b/mj)
(iiiy/MJ)
(nig/HJ)
(mji/M-l)
(mfc/MJ)
0.5i0.I
2.510.7
0.8! 0. 5
1 33.016.0
6.3J3.2
5 . B19. 0
0.7 i0.2
3.510.3
0.310.0
131.015.0
AA .0*5.0
0.6!0.1
0.91
A .At
0. A i
106.01
0.1
0.9
0./.
3.0
BU.013 3.0
1 .61 0.1
197 7 1owa/WyomLog coal
02 HUF ±'	50Z
w I r It
•a/
km
o.a
l .0
0.9
91.0
9./.
16.0
10.1
10. 3
10.
16.
11 ,
15
0.0710.00
1.9	i 0.1
3.9	l 0.2
0.6	i 0.1
00.0	i 5.0
110.0	i L 5.0
20.0	l 0.0
0.131 0.06
Parameter (unity)
I'a r I: I <• n 1 a I ea ( mill in I I f:d)
Pari Icnlales (unfoni ro I 1 ed )
Oxide:; of sulfur, -S0K
Oxides of nil inguii, N0X
Clil or Ides
I'orma I ili;liyde
llyd roc a r lie n s
(fc/H.I)
(b/hj)
(g/MJ)
(lllg/lil)
(in^/MJ )
(iub/M-I)
(ing/M.I)
60% load
197 7 I owa/Uyom I ng coal ultli
OX I IDF	201 K OF	507.RDF
0.7	i 0.1
2.0	i 0.A
1.A	l 0.2
106.0	iI I.0
A.2	i 1.1
2 2.0	112.0
O.Ofli 0.OA
1.8 1 O.A
3.7 1 O.A
O.fl 1 0.1
52.0 110.0
96.0 112.0
20.0 l 7.0
0.071 0.00
i^Only
1 . 7
0.2
A. 3 i 0.3
0.5 i 0.0
96.0 1 A.0
127.0 132.0
2 3.0 117.0
0.07! 0.01
I wo runs at tills load and 'L ItUF were nccoiti)>l I sited.

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Table 5. Selected Emissions from Boiler Unit 7


Prior to Installation
of Dump
Grates 1976,
1977



Parameter
Un it s
60%
Load
80%
Load

100%
Load



0%
RDF
0%
RDF
0%
RDF
10%
RDF
Particulates
lb/1.06BTUb
0.23
(0.07)a
0.35
(0.12)
0.60
(0.09)
0.53
(0.12)
(controlled)
£








Part iculates
lb/10 BTU
9.05
(1-02)
7.49
(1.72)
8.26
(0.05)
8.35
(0.30)
(uncontrolled)
c








Oxides of Sulfur
lb/10 BTU
2.61
(0.40)
2.88
(0.70)
3.70
(0.16)
2.88
(1.14)
SOx
c.








Oxides of Nitrogen
NO*
lb/10 BTU
0. 32
(0.03)
0.26
(0.09)
0.35
(0.02)
0.27
(0.04)
ilUA
Chlorides
lb/10qBTU
5.14
(3.75)
13.6
(8.42)
28.14
(6.91)
7.65
(5.05)
Formaldehyde
lb/lOgBTU
4.56
(5.58)
20.9
(44'.0)
5.49
(A. 58)
60.0
(52.6)
Methane
lb/10 BTU
0.00
(0.00)
0.00
(0.00)
0.00
(0.00)
0.00
(0.00)
After Installation of Dump Grates 1978
Parameter	Units	80% Load	100% Load
0% RDF	10% RDF	20% RDF	0% RDF	10% RDF	20% RDF
,-itos	ih/in6KTI' n.?1 (0.05) 0.17 (0.09) 0.37 (0.07) 0.4? (0.21) 0.A4 (0.07) O.ST fn.ng)
^V-VJIILLUJ. itU J	,
Particulates	lb/10 BTU 6.54 (1.33) 7.63 (0.63) 8.21 (1.21) 7.93 (3.58) 7.28 (0.53) 7.47 (0.53)
(uncontrolled)
Oxides of Sulfur lb/10 BTU 3.42 (0.14) 2.84 (0.16) 2.33 (0.63) 3.30 (2.07) 2.33 (0.49) 1.93 (0.51)
SOx
Oxides of Nitrogen lb/10 BTU 0.39 (0.02) 0.33 (0.02) 0.33 (0.03) 0.31 (0.04) 0.26 (0.01) 0.26 (0.03)
Chlorides	lb/lO^BTU 10.7 (1.77) 50.9 (35.8) 93.7 (8.96) 7.65 (1.88) 58.4 (31.9) 28.6 (9.35)
Formaldehyde	lb/1.0 BTU 8.37 (14.0) 12. (207.) 0.77 (0.42) 0.19 (0.33) 1.44 (0.72) 0.42 (0.19)
Methane	lb/10yBTU 5.30 (2.65) 6.07 (1.58) 3.77 (0.30) 3.35 (0.93) 4.58 (1.44) 2.47 (0.58)
avalues in parentheses are + one standard deviation
^to convert from lb/10^BTU to micrograms/Joule, multiply values in the above table by 0.430

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TEST FIRING REFUSE DERIVED FUEL
IN AN INDUSTRIAL BOILER
EPA GRANT NO. R806-328-010
GARY L. BOLEY, P.E.
PROJECT MANAGER
CITY OF MADISON, WISCONSIN
In 1979 the City of Madison and the investor owned utility, Madison Gas
& Electric Company, jointly implemented a prepared refuse derived fuel (RDF)
energy recovery project. The City of Madison owns and operates a solid waste
processing plant to process municipal solid wastes for the production of the
RDF. The Madison Gas & Electric Company utilizes the RDF in two Babcock and
Wilcox 50 megawatt pulverized coal boilers.
In the fall of 1978 the City of Madison in cooperation with Oscar Mayer
& Company were recipients of an Environmental Protection Agency Research Grant
to test fire RDF in an industrial boiler. The Oscar Mayer & Company could
represent a second market to the City for the use of RDF.
The industrial sector is a potentially large, user of prepared solid wastes
as a supplemental fuel source. Industrial boiler installations are not able to
take advantage of the highly favorable fuel price advantages that utilities can
obtain, due to their high volume consumption. Therefore, industrial users may
be willing to pay a higher price per unit of energy for RDF than utilities.
Research Purpose
The purpose of the research is to investigate the feasibility of cofiring
municipal solid waste with fossil fuels to determine:
1.	Industrial boiler operational performance when cofiring coal and RDF
at various boiler loads and feed rates to determine optimum operating
conditions.
2.	Air emissions and performance of existing mechanical air cleaning
system when cofiring coal and RDF.
3.	Operational characteristics of the RDF feed system and the reliability
and practicality of receiving, storing and firing RDF at an industrial
operation.
4.	Economic analysis of utilizing RDF at an industrial operation.
Project Participants
City of Madison
The City's grant responsibilities, in addition to providing the RDF, include
overall project management, detail design of the RDF receiving facilities and
overall project coordination.
88

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Oscar Mayer & Company
Oscar Mayer St Company operates a meat packing plane in Madison. As parr
of their plane operations, Oscar Mayer operates a power plane for the cogenera-
tion of process steam and electricity. One of two Wicks 125,000 pound per hour
boilers will be retrofitted for 3DF firing. In addition to providing the
boilers, Oscar Mayer will also operate the RDF receiving and firing facilities.
M. L. Smith Environmental
M. L. Smith Environmental was retained by the City to provide special con-
sultant services to provide technical direction and staff assistance in the
Engineering evaluation of 3oiler Mo. 5 to determine the method of SUP firing,
assistance in the preparation of the necessary documents for the boiler retrofit
work, develop the RDF receiving and feed process concept and system layout,
provide assistance in the test program development, and assist' in the prepara-
tion of the project's final report.
University of Wisconsin-Madison
The University of Wisconsin-Madison, contracted by the City, will provide
the facilities and personnel necessary for all sampling, data collection,
analysis, and prepare all technical evaluations and reports.
Existing 3oiler Conditions and Modifications
Oscar Mayer & Company's Boiler Mo. 5 is a Combustion Engineering, Inc.
(Wicks) 4-drum water cube type with a rated steam load capacity of 125,000 pounds
per hour. Tie 1 1/4" to 10—nesh coal is fed via a Detroit Stoker toco-grate
spreader. The bailer is equipped with Zura aulticlone separators for particulate
emission control.
After a detailed evaluation of the existing boiler coal feed and overfire
air systea, it was determined that it was desirous to fire the RDF as close to
the traveling grate as possible. The selected system will fire the RDF immedi-
ately above the coal feeders. The RDF is to be air swept into the bailer by
utilizing part of the overfire air. To insure an even distribution of the RDF
across the boiler width all six existing coal feeder locations will be utilized.
The existing coal feeders will be repLacsd with a combination coal-SDF feeder
assembly. The combination feeders are of a standard design used to fire coal in
combination with wood chips or 'nog fuel.
To insure adequate overfire air for RDF firing and combustion, the existing
overfire air system was replaced to provide an increased capacity in overfire
air volume. The induced draft fans have adequate excess capacity for the addi-
tional air volume.
RDF Feed Svsrem
The RDF feed system was developed to provide flexibility in feeding the
RDF at varying feed rates to aeet the research objectives and to provide a very
89

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BOILER NO. 5
Ml—l : ELEV. 137'3"
vO
o
R.D. F FEED CHUTE (6)
FLOOR ELEV. 112'0"
EXISTING POWER GENERATION PLANT
BUILDING SIZE 40' X 70*
PLAN VIEW
OSCAR MAYER a CO.
R. D. F. FEED SYSTEM
EPA GRANT NO R8O632B-OI-0
RUBBER BELT CONVEYOR
EL. 103'3"
n
¦ n n I .
AUGER 	
DISCHARGE
SYSTEM
R. D. I".	
RECEIVING
BIN
R.D. F. RECEIVING	
a FEED FACILITY
BUILDING SIZE 36' X 48*
-1
FLOOR ELEV. 105* 3"
DIVISION OF ENGINEERING - CITY OF MADISON, WISCONSIN
.DRAWN BY T.L.J. 1-30-80

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OSCAR MAYER a CO. BOILER NO. 5
BOILER FEED
EPA GRANT NO. R60632a-0I-O
COAL
BUNKER
BOILER NO. 5
_ SLIDER -
BELT
CONVEYOR
BOILER
NO. 5
-R. D.F. -
FEED
CHUTES
COMBINATION
FEEOER
(6)
COAL-
CIIUTE
~ AIR —
INTAKE
]LJ[
GRATE
FRONT VIEW	SIDE VIEW
DIVISION OF ENGINEERING - CITY OF MADISON, WISCONSIN
DRAWN BY 1 L.J. I-10-80

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clean system compatible with Oscar Mayer's high standards for plant cleanli-
ness for food processing. To maintain that standard, all RDF handling activities
will be housed in a building and all conveyors will be totally enclosed and
tightly sealed.
The delivered RDF will be discharged from the delivery vehicle (75 C.Y.
transfer trailers) onto a concrete floor. A small loader will load the RDF into
a surge bin. The RDF will be discharged from the bin by two fourteen (14") inch
diameter augers. The discharge augers are powered by a variable speed drive to
provide the variable RDF feed rates (1.5 to 10 tons per hour). The augers will
discharge the RDF onto a totally enclosed rubber slider belt conveyor to trans-
port the RDF to the boiler front. The RDF will then be split to feed the six
(6) combination feeders by use of a splitting roller and swinging chutes to
provide the desired feed into the boiler.
Test Program
The RDF-coal firing test program will consist of firing RDF at various
energy replacement rates and at varying boiler steam loads. Tests to be conduc-
ted will include (see Table 1):
1.	Characterization of all fuels used in the combustion tests.
2.	Stack emission tests while firing RDF and coal at the various feed
rates and boiler loads.
3.	Boiler efficiency at the various RDF feed rates and boiler loads.
4.	Operate the boilers for a sustained period at the optimum coal/RDF
mix.
RDF Quality
The RDF to be fired in the Oscar Mayer & Company boiler will be essentially
the same as presently fired at the Madison Gas & Electric power plant. That
RDF has a typical ash content of 10 to 127„ and a moisture content of 20 to 30%
as received.
Project Schedule
As of February 1, 1980, all RDF feed equipment and boiler equipment have
been ordered. Construction of all facilities is scheduled for completion by
June 1, 1980. It is anticipated that all test runs will be conducted during the
summer and early fall 1980.
92

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1'repareii by: The University of W1 flcona lu-Ma

  • -------
    TEST FIRING REFUSE DERIVED FUEL
    IN AN INDUSTRIAL BOILER
    EPA GRANT NO. R806-328-010
    GARY L. BOLEY, P.E.
    PROJECT MANAGER
    CITY OF MADISON, WISCONSIN
    In 1979 Che City of Madison and che investor owned utility, Madison Gas
    & Electric Company, jointly implemented a prepared refuse derived fuel (RDF)
    energy recovery project. The City of Madison owns and operates a solid waste
    processing plant to process municipal solid wastes for the production of the
    RDF. The Madison Gas & Electric Company utilizes Che RDF in two Babcock and
    Wilcox 50 megawatt pulverized coal boilers.
    In the fall of 1978 the City of Madison in cooperation with Oscar Mayer
    & Company were recipients of an Environmental Protection Agency Research Grant
    to test fire RDF in an industrial boiler. The Oscar Mayer & Company could
    represent a second market to the City for the use of RDF.
    The industrial sector is a potentially large user of prepared solid wastes
    as a supplemental fuel source. Industrial boiler installations are not able to
    take advantage of the highly favorable fuel price advantages that utilities can
    obtain, due to their high volume consumption. Therefore, industrial users may
    be willing to pay a higher price per unit of energy for RDF than utilities.
    Research Purpose
    The purpose of the research is to investigate the feasibility of cofiring
    municipal solid waste with fossil fuels to determine:
    1.	Industrial boiler operational performance when cofiring coal and RDF
    at various boiler loads and feed rates to determine optimum operating
    conditions.
    2.	Air emissions and performance of existing mechanical air cleaning
    system when cofiring coal and RDF.
    3.	Operational characteristics of	the RDF feed system and the reliability
    and practicality of receiving,	storing and firing RDF at an industrial
    operation.
    4.	Economic analysis of utilizing	RDF at an industrial operation.
    Project Participants
    City of Madison
    The City's grant responsibilities, in addition to providing the RDF, include
    overall project management, detail design of the RDF receiving facilities and
    overall project coordination.
    94
    

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    Oscar Mayer & Company
    Oscar Mayer & Company operates a meat packing plane in Madison. As pare
    of their plane operations, Oscar Mayer operates a power plane for the cogenera-
    tion of process scaam and electricity. One of ewo Wicks 125,000 pound per hour
    boilers will be retrofitted for RDF firing. In addition to providing the
    boilers, Oscar Mayer will also operate the RDF receiving and firing facilities.
    M. L. Smith Environmental
    M. L. Smith Environmental was retained by the City to provide special con-
    sultant services to provide technical direction and staff assistance in the
    Engineering evaluation of 3oilsr 'Mo. 5 to determine the method of RDF firing,
    assistance in the preparation of the necessary documents for the boiler retrofit
    work, develop the RDF receiving and feed process concept and system layout,
    provide assistance in the test program development, and assist in the prepara-
    tion of the project's final report.
    University of Wisconsin-Madison
    The University of Wisconsin-Madison, contracted by the City, will provide
    the facilities and personnel necessary for all sampling, data collection,
    analysis, and prepare all technical evaluations and reports.
    Existing Boiler Conditions ana Modifications
    Oscar Mayer & Company's 3oiler No. 5 i3 a Combustion Engineering, Inc.
    (Wicks) 4-drum water tube type with a rated steam load capacity of 125,000 pounds
    per hour. The 1 1/4" to 10-mesh coal is fed via a Decroic Stoker roto-grate
    spreader. The boiler is equipped with Zurn multiclone separators for particulate
    emission control.
    After a detailed evaluation of the existing boiler coal feed and overfire
    air system, it was determined that it was desirous to fire the RDF as close to
    ehe traveling grate as possible. The selected system will fire the RDF immedi-
    ately above ehe coal feeders. The RDF is to be air swept into the boiler by
    utilizing part of the overfire air. To insure an even distribution of the RDF
    across the boiler width all six existing coal feeder locations will be utilized.
    The existing coal feeders will be replaced with a combination coal-RDF feeder
    assembly. The combination feeders are of a standard design used to fire coal in
    combination with wood chips or hog fuel.
    To insure adequate overfire air for RDF firing and combustion, the existing
    overfire air system was replaced to provide an increased capacity in overfire
    air volume. The induced draft fans have adequate excess capacity for the addi-
    tional air volume.
    RDF 7eed System
    The RDF feed system was developed to provide flexibility in feeding the
    RDF at varying feed rates to meet the research objectives and to provide a very
    95
    

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    BOILER NO. 5
    ELEV. 137 3
    R.D.F FEED CHUTE (6)
    vO
    ON
    FLOOR ELEV. 112 O
    EXISTING POWER GENERATION PLANT
    BUILDING SIZE 40' X 70'
    13™—
    PLAN VIEW
    OSCAR MAYER a CO.
    R. D. F. FEED SYSTEM
    EPA GR/NT NO. R806328-0I-0
    RUBBER BELT CONVEYOR
    96 IO BETWEEN BUILDINGS-
    AUGER 	
    DISCHARGE
    SYSTEM
    R. D. F. 	
    RECEIVING
    BIN
    R.D.F. RECEIVING	
    8 FEED FACILITY
    BUILDING SIZE 36* X 48'
    
    FLOOR ELEV. 105" 3'
    DIVISION OF ENGINEERING-CITY OF MADISON, WISCONSIN
    DRAWN BY T L.J. 1-30-00
    

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    OSCAR MAYER a CO. BOILER NO. 5
    BOILER FEED
    EPA GRANT NO. RQ0632a-0|-0
    COAL
    BUNKER
    BOILER NO. 5
    ^ SLIDER -
    BELT
    CONVEYOR
    BOILER
    NO. i>
    -R. D.F -
    FEED
    CHUTES
    Qi
    \n
    COMBINATION
    FEEDER
    COAL-
    CHUTE
    " AIR —
    INTAKE
    LZJt	1(	ILL)
    GHATE
    FRONT VIEW	SIDE VIEW
    OIVISION OF ENGINEERING - CITY OF MADISON, WISCONSIN
    DRAWN BY T.L.J. 1-30 80
    

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    clean system compatible with Oscar Mayer's high standards for plant cleanli-
    ness for food processing. To maintain that standard, all RDF handling activities
    will be housed in a building and all conveyors will be totally enclosed and
    tightly sealed.
    The delivered RDF will be discharged from the delivery vehicle (75 C.Y.
    transfer trailers) onto a concrete floor. A small loader will load the RDF into
    a surge bin. The RDF will be discharged from the bin by two fourteen (14") inch
    diameter augers. The discharge augers are powered by a variable speed drive to
    provide the variable RDF feed rates (1.5 to 10 tons per hour). The augers will
    discharge the RDF onto a totally enclosed rubber slider belt conveyor to trans-
    port the RDF to the boiler front. The RDF will then be split to feed the six
    (6) combination feeders by use of a splitting roller and swinging chutes to
    provide the desired feed into the boiler.
    Test Program
    The RDF-coal firing test program will consist of firing RDF at various
    energy replacement rates and at varying boiler steam loads. Tests to be conduc-
    ted will include (see Table 1):
    1.	Characterization of all fuels used in the combustion tests.
    2.	Stack emission tests while firing RDF and coal at the various feed
    rates and boiler loads.
    3.	Boiler efficiency at the various RDF feed rates and boiler loads.
    4.	Operate the boilers for a sustained period at the optimum coal/RDF
    mix.
    RDF Quality
    The RDF to be fired in the Oscar Mayer & Company boiler will be essentially
    the same as presently fired at the Madison Gas & Electric power plant. That
    RDF has a typical ash content of 10 to 127. and a moisture content of 20 to 307o
    as received.
    Project Schedule
    As of February 1, 1980, all RDF feed equipment and boiler equipment have
    been ordered. Construction of all facilities is scheduled for completion by
    June 1, 1980. It is anticipated that all test runs will be conducted during the
    summer and early fall 1980.
    98
    

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    CO-FIRING REFUSE DERIVED FUEL (DROSS)
    IN A STOKERED 30ILER
    BY
    FRED R. REHM, P.E.*
    BACKGROUND
    Milwaukee County operates a co-generation power plant facility at its 900 acre
    Milwaukee County Institutions complex that encompasses a growing Regional Medical
    Center. This power plant is equipped with three (3)-110,000 #/Hour coal-fired
    Union Iron Works boilers and a single-125,000 fjfaour combination gas-oil fired
    Combustion Engineering boiler. The coal-fired boilers are each fired by a Hoffman
    "Firite" spreader stoker with a continuous front end ash discharge grate system.
    The coal-fired boilers were placed in operation in 1954 and each originally in-
    corporated an economizer, an air preheater and a Western Precipitation "multiclone"
    mechanical centrifugal dust collector. In 1979, three new UOP-Air Correction
    Division electrostatic precipitators were installed and placed into operation at
    this power plant -- one precipitator on each coal-fired boiler. This plant cus-
    tomarily bums an Eastern (Kentucky) coal of less than 2% sulfur content but has
    operated for extended periods of time burning a Western (Montana) coal with a
    sulfur content of less than 17..
    With the startup of the American Can Company's "Americology" refuse processing
    plant, limited test trials were conducted at this plant while firing both the RDF
    "lights" and "heavies" (dross) fractions in conjunction with coal in the spring
    of 1977. This RDF firing was conducted using a temporary pneumatic firing system that
    utilized a farm silage blower setup similar in many respects to the improved pneumatic
    firing system that had been utilized in an EPA R&D project at the City of Columbus,
    Ohio municipal power plant. These preliminary firing tests showed sufficient promise
    that an EPA R&D grant for more extensive and definitive evaluation of co-firing
    of the dross or RDF "heavies" fraction along with coal was sought and received
    in late 1978. Dross, or the "heavies" fraction, is the material left after
    mrnicipal solid waste :'.s processed to produ::r a refined RDF "lights" fracticn
    suitable for utility firing, a ferrous fraction, an aluminum fraction, and a glass
    fraction. The remaining material (dross) was demonstrated to have a high com-
    bustible content, but because of its unsuitability for firing in a suspension-fired
    utility boiler, it is normally destined for sanitary landfill. The Americology RDF
    "lights" fraction has been burned in the Wisconsin Electric Power Company's Oak
    Creed Station #7 and #8 Boilers for two years now. Those that have attempted to
    burn RDF in suspension in utility boilers have found that it must be substantially
    free of metals, glass and other abrasive materials in order to avoid excessive wear
    and pluggage problems in the pneumatic transport lines and to minimize slagging and
    other problems associated with boiler operation. Utilities have also learned that
    the denser combustible material in RDF tends to fall through the furnace without
    burning completely. Unless a grate is furnished in the utility furnace to retain
    this material in the high temperature zone, the heating value of the denser material
    is lost. Generally, speaking, the steps that have been taken to improve the quality
    of RDF "light" fractions for suspension firing tend to increase the quantity of
    dross or "heavies" that must be disposed in a landfill. The denseness of this dross,
    * Director of Environmental Services, Milwaukee County, Wis.
    Presented at U.S. EPA-IERL "Waste-To-Energy Technology Update 1980",
    April 15-16, 1980, Cincinnati, Ohio
    100
    

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    which makes it unsuitable for suspension firing in a utlity boiler, enhances its
    value as a fuel for a traveling-grate, spreader-stoker firsd furnace. Thus, the
    dense material tends to fall on the grate to effect complete combustion rather
    than float up and out of the furnace as additional particulate. Our grata speeds
    are relatively slow and hence furnace retention time in our boilers ac rated
    capacity operation is approximately 80 minutes. Consequently, the successful
    firing of the RDF "heavies" fraction in our spreader-stoker fired boilers is viewed
    as supplemental or complementary to the burning of the RDF "lights" fraction at
    the Wisconsin Electric Power Company pulverized coal-fired boilers.
    PROJECT OVERVIEW
    The RDF "heavies" for our project are to be supplied by the Americology plant.
    Approximately 3000 tons are expected to be utilized in the 3 month test and evalua-
    tion period. The following quality criteria have been established for the "heavies"
    fraction.
    Less than 127. glass by weight
    Lass than 37. metals by weight
    Less than 257. total noncombustibles by weight
    Less than 337, moisture by weight
    A nominal top size of less than 4 inches
    Average heating value range 4000-4300 3tu's/#
    The RDF "heavies" are to be transported to the plant by use of Waste Management,
    Inc. 15-ton self-unloading trailers. For the purposes of this project, on-site
    storage to provide for an uninterrupted supply of the RDF will be effected by use of
    Waste—Management trailers. The County's power plant is approximately 6 miles and
    10 minutes away by direct freeway travel from the Americology plant.
    The RDF fraction will be received in a screw conveyor bottom receiving bin
    capable :of receiving a substantial portion of a full trailer load of RDF. The
    trailer will be positioned to continue to feed the receiving bin as the RDF is
    burned. We anticipate an RDF feed rate ranging up to 5.5 tons per hour for these
    tests. Fcr •purposes of these tests this arrangement will forestall the need for
    supplying a large RDF receiving and storage facility. The rate of operation of the
    screw conveyors in the receiving bin will be the mechanism for control of the RDF
    feed rate to the test boiler. One of the three exising boilers will be used in the
    project. The controlled RDF feed material will be fed to a pneumatic airlock feeder
    and will be transported pneumatically to the front of the test boiler. A single
    pneumatic injection RDF flared feed spout will be located in the front wall of the
    boiler approximately 10 feet above the top of the^travelling grate. This location
    is approximately 7% feet above the centerline of/^oal-feeder reel which projects
    coal into the furnace. An extensive evaluation has been made by our consulting
    engineers on this project, Charles R. Valzy Associates, Inc., of the possible use
    of a mechanical RDF transport system at our plant in lieu of the pneumatic system.
    All parties involved in the project would have favored the use of a mechanical RDF
    conveying system to avoid' some of the demonstrated problems found by others that
    have been associated with pneumatic RDF transport. Unfortunately, physical space
    limitations within the power plant make the use of a mechanical RDF conveying system
    impractical.
    101
    

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    The first two months of plant operation will be used to establish the optimum
    RDF-coal combination firing rates at various boiler load rates of operation. During
    this trial period, consideration will be given to the following parameters in
    establishing and evaluating the optimum RDF substitution rates:
    RDF receiving, transport and firing system problems and limitations
    Impact on the steam generating capacity of the boiler
    Stability of steam generation
    Excess air requirements
    Boiler thermal efficiency impacts
    Carry-over of fuel into the boiler convection bank and boiler slagging
    Grate residue and fly ash production
    Residue combustible loss
    Adequacy or limitations of our pneumatic boiler ash conveying and ash
    storage facilities
    We expect to explore RDF substitution rates ranging from 20% to 50% of the
    total boiler heat input at boiler steaming rates ranging from 60% to 100% of
    rated boiler capacity.
    Once the two month trial period is completed, we plan to operate the test
    boiler continuously for approximately thirty (30) days at the optimum RDF input
    rate established in the trial period at or near 80% of the boilers rated steaming
    capacity -- the normal rate of boiler operation at this power plant. During this
    30-day test period, we expect to conduct a comprehensive system and environmental
    performance analysis. The boiler and its related firing and ash handling systems
    will be evaluated and assessed for the aforesaid operating parameters previously
    outlined. RDF and coal analyses will be regularly conducted for heat content,
    moisture, ash, chloride and sulfur contents. A limited number of analyses of the
    RDF and coal will be conducted for their heavy metals content. Concurrent electro-
    static precipitator inlet and outlet particulate testing will be performed both
    while burning coal alone and at the optimum RDF coal substitution rate. The sampled
    particulates will be analyzed for resistivity, combustible content and particle
    sizing. Gaseous emissions will be assessed for criteria pollutant loadings as well
    as for hydrogen chloride. Gas volume and temperature measurements will be made and
    Orsat analyses will be conducted. The grate ash residue will be quantified and will
    be analyzed for Btu content, combustible content, putrescibles and leachate potential.
    Much of the environmental sampling and analytical work for this project was to have
    been done by EPA contractors which were funded outside the grant project. Conse-
    quently, we will have to carefully prioritize the sampling and analytical program
    conducted to stay within our project's budgetary limitations should EPA funding for
    this aspect of this project be restricted, as now appears to be the present situation.
    Our present timetable calls for our field testing program to be conducted in
    the Fall of 1980. We are restricted to the conduct of the field portions of this
    study to either the Fall or Spring of the year since the stean & electrical load
    demands in this power plant for our Medical Center would preclude the availability
    of the test boiler for this project during the heavy winter heating load and summer
    air conditioning load periods. The field test portion of this project was originally
    scheduled for the Fall of 1979. However, due to an explosion at the Americology
    plant and subsequent changes and modifications made at that plant, it was necessary
    to delay this R&D project by one year.
    102
    

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    PROJECT STATUS
    We have conducCed numerous operational tests at the Americology plant in the
    past few months directed toward upgrading the quality of the RDF "heavies" fraction.
    This has involved some plant revisions in the plant's RDF "heavies" processing
    operations. While the RDF "lights" fraction processing lines have now been modified
    and adjusted to produce a high quality RDF "lights" fraction for firing by Wisconsin
    Electric Power Company, there have been limited permanent revisions made to the RDF
    "heavies" processing system to date. Consequently, there has been need to make
    temporary changes in the mode of plant operations and in the upgrading of the netals
    and glass removal operations to improve the quality of the RDF "heavies" fraction
    to facilitate and enhance its handling and firing capabilities. Should the R&D test
    program ultimately prove successful and markets for the RDF "heavies" fraction become
    available, the Americology people would then consider incorporating the aforesaid
    temporary system changes into permanent modifications to their system that would
    provide a RDF "heavies" fraction of equal or superior qualities than those used in
    this research project. The analyses of the RDF "heavies" fraction from one of the
    series of recent operational tests is shown in the accompanying chart. It is felt
    by the Americology people that the quality of this material can be further improved
    by fine tuning the various operating systems in the plant during periods of more ex-
    tensive running time than those provided in the ^ hour or 1 hour test periods that
    were used in the operational test runs to date ana which would be required during
    the actual R&D project burning period. Additional operational test run3 will be
    conducted under varying operating conditions at the Americology plant in the coming
    months to further reduce the quantity ox material greater than 4" and to reduce the
    amount of glass and other incombustibles in the RDF "heavies" fraction.
    Preliminary evaluations and designs for the RDF handling and firing syscem
    at the power plant are nearing completion and are expected to be completed soon
    and the installation of the RDF handling and firing system is expected to be bid
    in the near future.
    Precipitator particulate emission tests have been conducted on all three coal
    fired boilers while operating at rated capacity while burning Eastern coal. These
    emission tests were conducted as part of the performance- acceptance tests for the
    new electrostatic precipitators. These test results will be utilised in establishing
    the baseline for comparing the emission results of coal only burning versus co-firin"
    of coal and the RDF fraction. A table showing the preliminary results of the partic
    late emission tests for the ?;3 boiler is attached.
    103
    

    -------
    HEAVY FRACTION FUEL ANALYSIS
    TEST ON 1/24/80
    NON-FERROUS &
    MOISTURE = 26.7%-
    BONE AND
    FLOATABLE ASH =
    FUEL
    GLASS
    14.6%
    TAILS =2.7%
    NOTE: PERCENTAGES SHOWN
    AS RECEIVED BASIS.
    PARTICLE SIZE (AVERAGE OF 3 SEPARATE SCREENINGS)
    4"
    78%
    2"
    71%
    14"
    65%
    1"
    56%
    3/4"
    45%
    V
    31%
    104
    

    -------
    Table 1. Summary o' the Results of the May 30, 1979 ESP Performance and Particulate Emission Test on the No. 3
    [toller ESP firod with Eastern Coal at the Milwaukee County Institutions Central Power Plant In Milwaukee, Wisconsin.
    1 Tf.M
    RUN
    \
    RUN 2
    RUN 3
    INLET
    1 OUTLET
    INLET
    OUTLET
    INLET
    OUTLET
    Tlmo ol Test
    (MRS)
    1020-1130
    1015-1130
    1220-1350
    1230-1347
    1418-1535
    1415-1530
    Stearn f1ow
    (lO'LU/IIR)
    109. 1
    109. 1
    1 10.9
    110.9
    109.8
    109.8
    Pcrconl of ratec
    capacity
    99.2
    99.2
    100.0
    too.a
    99.8
    99.8
    Vo 1 unto 1 r I c Mo*
    
    
    
    
    
    
    
    ACTUAL
    (ACFM)
    66600
    63200
    67100
    66200
    66700
    64600
    STANDARD
    (DSCFM)
    39400
    37900
    30700
    39000
    38800
    38400
    Gas Temperature
    (DCG-F)
    356
    344
    363
    345
    362
    345
    Gas moisture
    i% v/v)
    6.43
    6.24
    7.99
    7.78
    7.42
    7.08
    Gas composition
    (% v/v, dry)
    
    
    
    
    
    
    carbon dioxide
    11.13
    10.94
    11.31
    10.97
    11.18
    11.17
    oxygen
    
    0.32
    0.63
    8. 14
    8.65
    8.27
    8.35
    n 1 1rogun
    
    00.55
    00.43
    00.55
    00.38
    80.55
    00.48
    TIme-averayed velocity weighted
    
    
    
    
    
    
    oxygen
    (% v/v, dry)
    7. 74
    8.66
    7.76
    8.43
    7.97
    8.42
    Particulate concent rat i on
    
    
    
    
    
    
    ACTUAL
    (GR/ACF)
    . 11
    .024
    . 1 1
    .021
    . 1 1
    .024
    STANDARD
    (GR/DSCF)
    . ID
    .040
    .19
    .035
    . 19
    .040
    Isokinetic variation 1%)
    99.7
    90.3
    103.9
    101.7
    103.0
    100. 1
    PartIculale mass
    rate (LO/llR)
    59.7
    13.0
    65. 1
    11.7
    63.0
    13.0
    ESP co 11ec ti on ft
    t 1 1 ciency (jC w/w
    
    70.2
    
    02.0
    
    70.4
    Pressure drop across ESP (in. wc
    
    .53
    
    .53
    
    .53
    Particulate emission factors
    
    
    
    
    
    
    
    (Ln/I06I3TU)
    
    
    
    
    
    
    Co.i 1 'low me 1 hod
    .45
    .099
    .50
    .089
    . 48
    . 102
    Steam flow method
    .46
    . 101
    .50
    .009
    .40
    . 100
    F-Fuclor method (02 Analyze
    ) .39
    .097
    .43
    .082
    .42
    .093
    F-l ticlor method (orsal)
    .41
    .096
    .44
    .083
    . 43
    . 092
    
    
    
    
    
    
    
    
    

    -------
    CORROSION INHIBITION IN REFUSE-TO-ENERGY SYSTEMS
    H. H.  Electric ?lant. The Sanitation
    Dlvisipn transfer trucks had tp oe emptied in 20 to 30 minutes during
    the daytin* to avoia relaying snredaer ooeration. Put could be used for
    storage and/or retained for longer periods at nignt.
    Assuming an average steam flow of 100,00 (b/hr (45 Mg/hr) and
    :0 sercent of tne neat generatea by refuse, tne amount used per nour
    would be about seven to eight tons (6 to 7 Mg). Thus, a truck load of
    refuse could be delivered to the power plant every two to three nours during
    the day and also through the night by storing refuse in the trucks from
    the daytime operation of the snredders. After consideration of the
    available space and possible equipment arrangement at tne power plant,
    it was decided that the most suitable and cost-effective storage unit
    -ould consist of a bin similar to tne transfer truck body with a nyorau-
    11c ram to feed the refuse as required.
    The remainder of the external system comorised: (1) Peater
    bars at the end of the bin to break uo the refuse, (2) screw conveyors,
    (3) a 30 in. rubber belt conveyor, and {*) an inverted i hooper to receive
    the refuse from the cpnveyor pelt and direct it into two screw conveyors.
    The refuse storage and retrieval system is shown in Figure I.
    The refuse stream was divided at the Y hoooer so tnat the
    larger portion was fed to the front of the boiler, near tne soreaders.
    The two screw conveyors inside the building delivered tne refuse to Riley
    air-swept soouts wnicn were inserted in the side of tne boiler, at a 90
    degree angle to tne grate. The modification of tne boiler tubes to
    acconmodate the spouts is shown in Figure 2. Wnen tnis boiler was con-
    verted to a spreader stoker some years ago. the direction of tne grate
    travel was not cnanged, so tne grate movec away from the spreaders. For
    this reason about two-thirds of tne refuse -as introduced througn tne
    soout on the rignt. just in front of tne soreaders. The boiler modifi-
    cation also Included installation of overfire air jets beneath tne refuse
    spouts and across the back of the furnace. Ouring corrosion prooe expo-
    sures tne refuse feec rate was three to five tons/hr.
    Refuse Comoustion
    The boiler used in this program is rated at ISO.000 lb (68 Mg)
    pf steam per nour, but normally was operated over the range of 70,000 to
    125,000 lb (32 to 57 Mg). In order to insure good distribution of refuse
    across tne furnace, a rotating damper in tne duct of eacn air-sweet spout
    produced pulses to vary the input. The fuel trajectory was concrolfed oy
    angling tne distributor plate either 
    -------
    Corrosion faults
    Corrosion rates «trt	oy -«iqnt lots .nttsurw*nca
    jfter rwvil of me react** matal Jiinq innioited 10 oercent H3SO4 -nile
    me sarnie «4s Mde tu vales :atnodlcto 4 caroon 4nooe. The corrosion
    rate in nils Otr tour «4S calculated from me *tignt loss, 4ssur8inq
    jntfom attaci iround ye lStcimm surface. fhe corrosion fjtts m me
    coflring nvironrr^t for Aiaa ciroon steel is 4 function of :1m ire
    tnown «n .'Igure 3. The corresoonaing rues for !00 oercent refuse to®*
    Sustion *tre ootatnm from Mt orevtous txooiures ;o .^ass ourning of
    refust 4c me .Hani County incinerator imj jrc snow* In figure *. • itn
    niqn* sulfur coal ino uo to *6 -tignt-otroent 'tins*. me initial racts
    «trt 'ttiuceti oy 4 factor of ten. As m* exoosure time increastd, mt
    rates for 100 Jtrcent refuse ind ccal olus refuse oeca» cldstr. out mt
    s/14041 of mt cjr»ts inatcati mat 'or utended ooosurrs in conrojivity
    of mt 100 oeroent refuse canoustion environment ^ 111 ot ioout 5 to 10
    ;tni m4t of lit mgn«iulfur tMl «tut refuse.
    in gtntral, mt rotes .'or m« refuS«*C04l .nliturts »er« aoout
    mt same is for mt coals 4lone. '41 w caroan steel im 3 otrewt sulfur
    C04l, jjrmion rates sMgntly greater ic 700 4rtd 400*? (371 ind
    462*C). ?or me S stretnt ml fur cul mt relatively sign rates **r* mt
    result of sulfur attaci on mt stfrti. JU of mt corrosion rates nMiurM
    4c me Coluwxis site <«n* saaller man most found .'or sulk refust Ournmq
    3y 4C Itest 1 .'actar of tM, 4n4 In $ooi cases, oy 1 'ictar of Mfty.
    Di« fnlti4l carrwicfl r*cas (3-ftour) for AlOfi su«i a a .'ynctlon
    of 1*9 rtfm« 3«rcaflU9« In Lit .'y«l 41-t oresencta In flgurt 5.	riMS
    ««r« euer»ci*!1y inseo«ttd«nc 3/ :.i« 4flounc of ^?fus« In nixCurt, 40
    ia 1*9 1% •ciqAt-oireent 'jirt. D>« 1Q0 a«rc«nt <«lues in :n« Mqurt «r«
    yie ouli refuse iflcm®rjt1on eaO«r1a*«nes. 4nd U i 1 outet 9oss1bl«
    Vt«C ^ts« v«lu«i «ou)d a« a>0««r if mr»cfl*G r«fus« ««rt lurnM unatr tanr-
    Mrtoit drcienuftces.
    •fttn tflt eioosurt :iam *41 ieriqtntflefl to 30 noun, zm cornj^ion
    rjtss for ill of :ne j:«Is ««r* r«ucw 4s 4 r«sule of :ne :rocac:iv«
    oiiot l4y«n «ntci 3#v«loow3 on 1*9 ncil surficsi. 4$ found in :n« «ione
    .vjur tMOomrti, :.** '/Q9 JIO uainltss kmI n4d cn« lowvit comsion net.
    follow 5y tn» T*99i J16 100 tcamless tcnii. rh« '9 411 oy -na 4
    11»cjjicly Aigftvr *4t«, 4«» :n* iCJCtir in tn« 341« for cn« P9 totciowil 11
    4Ctri0u(«d to tfM®ty:y of \*i\ lUoy to 'jnnryj tulIUq if *.n« zxi49
    flln. fMi iffKt «ouid result in sen* ineaniMetncies of ««iqnc loss
    imnq vtt swles. il:nou<5n l*t« corrosion rits for A106 caroon icmI *4k
    uqniflcandy lo*«r v.tr :rwc 'or #iqnt .*reur noosur«j. it »4S mil ioout 4
    factor of :tn ^nattr man *jiat for \r,9 uamltss s:t«is.
    Hit inttrrolatta <4iuts for ir,9 lonq^ctm corrosion rsa?s *rt
    ^v«ti in r^olt I, -aten inciudts data fzr 1*9 /C3 naur con-^jtgn arso* «*PO-
    sur«. ^s tnoM in :n« uol«, corrosion ''acts <;tn«rally decreased fur*.i«r
    «itA ct« lonqtr '.in. to -«trc v,f«y navt oroMoly l«wl«d off *ould
    .tat S9Crsn9 s1<^itficantiy -its uiditional «iootun. Tyce 210 ttainl«is
    fCMl, *^lcn ilr*4dy Ud 4 very low corrosion ratt for ;ne 79 iour timun,
    incurred V9 14m rata H 500 4nd 700*5 in 708 nour tiooiure, -Ufi i
    'itcrtast 4C TOO*?. At j .^tcil t«oer3Curi jf 50Q*P :.ld *106 cnl ilio
    .ltd Vt9 lant rsct for *jt« r*o excosurv ttsvs. (t snouio :• nottd Lite
    -«#n on# itrcmc ml fur cotl «4s oum«d «icn only 1$ -^Kjnt-ctrcwt r?fyst
    {Proot -uJ), tne comsicn r»ct of -*106 ixtdl -as Mgn«r. r?itt r«sult
    inqicatas «"uc wH Ic»-43 >0 critical :otlir^, 44C.1 «itf 4 mammal ciMd'.y of 340
    r/day (127	:ay) of refust. it yij ritt of IS tans (13.5 if
    ••fusa :«r iour, :.i« nonnal	:racuction ii 32.500 io/!ir J42.3 ^/fr).
    Hit Ct4fl orestun u :nt fuotmtaeer outlet m ^SO ssig J"!3.5 '*gj ;er :4y of zry solios. ^ur^ng ;.-e course of vitst
    :orros«on studies, we :ar*i|l!/ jHec sludge *4S velivtr^d Jt jn 4*«rsgt
    -ate of lfi.S tons MS ^g) atr zoning siy. Ourmg t.ie 3-^our jnd 20-"Our
    3root eioosures. tne «eignc ratio of sluage to solid -astt >as icout i:10
    on dn 4$-r«cti*efl iasis. Out tyring :.it long-:jrn rjn t.ie ritio oroooed to
    lOQut 1: -*C
    is t'jrrenfjy ;rict:ctd. *."« te^terw sluage 'ilttr :»«e :on-
    utninq ioout U otrcsnt solios 'S aiieo *1 t.i tne ¦numeral refuse in t.ie
    .-ecsfing 31;. lanndtraoie ^uing occurs in tne oit tefort t.ie sludqt
    tnc "t'usc ir? 'ti fnto t.ie '-jr-ace :.*.ar5:nq c.iute. it seefneo likely t.na;
    suifur inc iiHci ««rs jrese^t in tae ^luagt in sufficient ;uanoty ina
    •er* :urneo est results ire tonoarrd -«w t.ie
    :orrosion data ootained oreviously it tfle .Hani County inc'fleritor it
    "roy, Ohio, «ntre oul'i refust alone «ts :umed. Hit data *«re interpolated
    fro® several lotcimtn ternotracures to 1 cofltnon temotracure of iCO*^ '.250*t).
    rhis teootraturt 9 corrosion rate «as sligntly niqntr it Troy otcaust vtt
    3root tntre *as excostd 10 some flart natation.
    addition of sewtgt sludgt to wit refust reduced t.ie initial
    corrosion r»t* of W caroon r.Mt 5y soout 1 fsctor of t>o. itr««ver. is
    tst ?*oosure tin* tncreastd. tnt corrosion rites for octrstion w»t.i jnd
    • unout sludge convergeo. Thus it tat 300 wur ooint. t.it rite «>oerienc»d
    for tnt s.'aall muntl of sludgt 3urned 4t Harrisourg *ts only sligntly less
    man mat for refuse alone it tnt 7roy [ncinerator. levertreless. if t.it
    4lfffrmc8 In tnt t>d cjrvts at me 1000 ie *?2 alloy nad ^tal
    •4stage rates essentially t.it saint is most for t.ie tarocn steel. Sig-
    nificantly lototr rites *tr« oostrved for me Tyoe JIC ind J*7 stainless
    Jtttls ind tnt incoldy 32S.
    tffect of «etal 'effotrsture
    A slot of «4SCagt rites for -i 106 carocn ttatl over me te^otrature
    rimjt jOO to 300*F for me ngnt nours «*oosure to t.ie Oum«ng refuse -itn
    ind -1 tftouc sludge loouion^ is irra^n in figure 7. "nt line ora««i on :iu
    figure frca me studies conducted 4t tae Troy, Ohio, incinerator Is oaseo
    uoon ten or rore A1C6 soeciotns ixoosed it 1 ;as terotrsture of 'WO*?
    (316*C) «nicn is cs««raoit to met :f me Marruaunj srooe in me suoer*
    ieater inlet, rht increase in corrosion *ste starting it 300*? (*27'C) ts
    tyoical of mat found for caroon s;iel ind lew alloy steels in our 34st
    eiocnenci vim me 3uminq of ouU refuse 4t ncn ;as temtratures. The
    mrev oaca ootnts ootaintd for me ciroon steel exoosto :o coffotraole ton-
    Jiticns in me Harrisaurg Incinerator fall clost to tne curve tstaoMsned
    for mt Troy incinerator, rhe corrosivity 3f me tnvirowwnt -41 signifi-
    cantly reduces «n«n tnt sewage sluoce **i ourntd -it.i t.ie refuse, -s
    snown in 'igure 7. mt eignt ."tour corrosion rates «im sluaqe ore^ent in
    mt futl ire Z to 2.2 tines lower tntn taose «i m refuse ilone.
    Similar conditions ind results ire s.iowi in "'.gyre 3 for me
    low taromiua il»oy. 'ZZ no* ^etng -jstd for me suotrreatar tuces 'n me
    harrisourg incineritor. r>ie olfferencs :n corrosivity of t.ie r*o fuels
    aecooes i*re ;ronounceo -'or totn illayi is me T*tal tmoerature increases,
    ^rtre again me line sra»n in :,ie figure mi ootamed it *roy for i mnilar
    low enroffliufl illoy. *11. (n cemoarmg tae Jtrfomance of ciroon steel ino
    '21 -ntn sewagt sluage *as turned aim t.ie .-ef'j.«e. littla iifference -4j
    soservtd in me ::rnsion rates, ss .iotsd in ;iguns 7 ind 3. «hen r-'use
    ilone -as ourntd me corrosion rste for 722 liloy -4S sli;n?'/ '3-er man
    tnat of i106 it terroerstures jo to -'CO*? [270"!). ^cwtver. it ioout 300*?
    (¦*27*C) tnere «as little difference in tae corrosion -ice of tae t'*o
    rsaterials. These results iroicace mtt t.ie reduction in :uce 'ulures 4t
    tae H4rrisourg incinerator sn recent years -45 not mt result sf reolacmg
    caroon steel tuots -'ta mt *22 illoy.
    3om T/gt )10 ino 3*7 iutnless steel is tst tlg.i caroaiun-^ickel il'oys ifforted
    rore orotectlon is me trroerature incroastd. ;rnoaoly :ue to ^or? *ioid
    diffusion of tae mrsmium ina nickel into tae ou'de liyer -it.n t.:e 'oma*
    tion of \ mic*er jrotective scale. *>:« iOdition of sludge to tae rer'-jst
    •ao oracticjlly .10 affect 3n tie corrosion rues sf T/oe 3*0 ino 3^7 stain-
    less scttl. T^e sludge 3td. io*«vtr. sMgntly r~juce tie ittac* on
    [ncoloy 325. oarttcuiarly it >o«tr tesiotntures.
    Iffect of las 7eraerU:jre
    *or mis srograw '.••o oiffer-nt 'ocac:ons for ;rooe ncosure *er*
    selected :n tne Jasis of meir 54s teiaoeritures. The ngner te^oerature
    location «4S in 'ront :f me f*>st suoeroeater oan« ino j feet oelow tae
    location 3f tne slant memocouole 'or fumace te^oeritur* ?ta»urefv»nt.
    jas te«Oeracures in mis :one ire romtored ind itintamtd ".ear !:00*r
    '31S'C ].
    :>o of t.ie eignt idur ;rcot "ins -ere iace *n 1 relatively too!
    location «nica «as icout ;5 ft :ow^strein> of tae rotter location. 5t mm
    joint mt vjees •««•< 3racticaliy tUc* »no tie 54s teroenture is xn»t;reo
    107
    

    -------
    by una orobe thermocouple was in the range HOO-12QO*F (593-650#C). The
    corrosion raws of tne carpon steel and the P22 alloy exposed at low gas
    temperature snowed only a slignt variation Kith metal temperature as com-
    pared to Figures 7 and 8 where the corrosion rates Increased raoidly with
    ratal teocerature wnen exposed to high gas tenoerature. The corrosion
    data demonstrated that the same reduced temperature dependence existed at
    low gas tempera tyre when the sludge was burned with tne refuse. Under
    these low-temperature conditions, utere »as no apparent difference in we
    corrosion rates between the caroon steel and the ?IZ alloy.
    It srtould be noted that a reduction in gas temperature Is more
    effective in reducing trie corrosivity of the environment over the entire
    ratal temperature range tnan is the addition of sludge to the fuel. Thus
    although additives to the refuse nay imgrove the life of boiler tubes the
    design of the Poller to reduce the teaoerature in the steam generator
    section would also provide a significant improvement In boiler tuoe life.
    CONCLUSIONS
    The experimental program conducted at the Columbus. Ohio
    .Hunicipal Electric Plant has demonstrated the technical feasibility of
    mechanical handling and furnace feeding of orocessed municipal solid
    waste at an existing stoier-fired Doller with United space and acces-
    sibility. It also has Seen shown chat the refuse comoustlbles can be
    burned completely on a grate in conjunction with coal, utilizing a
    spreader-stoker.
    The following specific conclusions can be reached:
    1.	The corrosivity of combustion products from cofiring
    refuse and three percent sulfur coal uo to a three to
    one weignt ratio is only slightly greater than that
    of coal alone.
    2.	Boiler tube metals can oe ranked in the following order
    of increasing resistance to corrosion: A106 carbon steel,
    ?9 low alloy steel and Types 316. 347, and 310 stainless
    steel.
    J. The corrosion rates of boiler tube metals decrease
    raoidly witn exposure time. After 700 nr the rates for
    stainless steels level off.
    Corrosion prooe exposures conducted at the Harrisourg, Pennsylvania,
    incinerator demonstrated tftac tfie addition of low-cnloride sewage iluage to
    municipal refuse reduced the corrosion of susceptible ratals caused by chlorine
    in en* refuse. Soeciflc conclusions from this researcn prograoi were:
    1.	The corrosiveness of the refuse combustion environment
    to carDon steel as indicated by 8-nour exposures was
    only 1/2 as great with sewage sludge present. Less
    reduction occurred at tow temperatures witn 722 steel,
    very little witn Incoloy 325 and essentially none witn
    Types 310 and 347 stainless steel.
    2.	For carton and low alloy steels the corrosion rates
    increased with ftetal temperature in the range S00-300"F
    (260~482°C), 
    -------
    house i. nsniss	stste! at coluxsus, ohio
    municipal siicntic ?unt
    3oii«f b«
    modificstfort for
    Qir-iw€?1 sooyts
    t'gs?.z :ntsl?ac: tsansto rrs~
    AMD 30ILZR :*.00EJICATICS
    109
    

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    Metal Temperorures
    950F 510 C
    750 *00
    550 270
    0.2 5
    Hours
    Metal Temperaiures
    X
    950 F
    5I0C
    ~
    750
    400
    <1
    550
    270
    0
    350
    180
    t 0.05
    Hours
    1000
    CORftOSICN RATES OF A106 CAABO.M STEEL AS .
    FUNCTION OF TtllE FOR COfniNC OF REFUSE
    AMD HtCH-SULFUR COAL
    COttOS tCW RATES OF A106 CARBON STEEL AS .
    FUNCTION OF TC1S FOR INCINERATION OF
    SULK RETJSE
    0.20
    = 0.15 -
    OJ
    o
    o:
    o 0.10 -
    o
    U
    .9 0.05 |-
    'c
    Metal temperature
    •	500 F ( 260C]
    •	900F (482C)
    I
    I
    I'l
    Jh
    /
    /
    4J
    aj
    2 £
    2
    0
    1
    I
    0
    0	25	50	75 100
    Weight Percent Refuse (with 3% Scoal)
    INITIAL CORROSION RATES (8 KR) FOR A106 CARBON STEEL
    AS A FUNCTION OP REFUSE PERCENTAGE IN THE FUEL
    (100 PERCENT VALUES FRCH BULK REFUSE INCINERATION)
    110
    

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    M«nn *«mo«rQTuff, C
    *00
    Tgo««
    Q Staam 3to«n
    I ^
    3 -5
    3 :
    5 "
     
    -------
    C0-F1KJNG DENSIFIED REFUSE DKH1VED FUEL
    IN A SPREADER STOKER FIRED BOILER
    Gerald H. DegJer
    Carlton C. Wiles
    ABSTRACT
    As a resource recovery a1tt-irnative, the use of refuse-derived fuel (dRDF)
    is being investigated as a substitute for coal in industrial spreader
    stoker boilers. Experiences are sumir.arized from the combustion testing of
    1/2-inch-diruncter pellets using a modified animal pellet mill. Storage and
    handling experiences are also discussed.
    Approximately 1800 MG of dRDF have been burned in a spreader stoker equipped
    boiler. The first phase of the combustion tests involved an evaluation of
    boiler performance and emission when firing at coal:dRDF blends of 1:0,
    1:1, 1:2, and 0:1. A total 245 Mg of 1/2-inch-diameter by 3/4-inch-long
    pellets were consumed during these tests. The second phase of the combustion
    tests involved the combustion of 1555 Mg of pellets. Results are presented
    primarily from the Phase 1 test. Results from the Phase 2 test will be
    available -in the near future.
    INTRODUCTION
    Densified refuse-derived fuel (dRDF) is considered one of the more marketable
    products recovered from municipal solid waste. UTien densified in the form
    of pellets, cubettes, or briquettes, it can be easily handled, transported,
    and blended with coal and burned in existing stoker fired boilers without
    major equipment modification.
    As a result of previous encouraging coal:dRDF tests, the U.S. Environmental
    Protection Agency sponsored a technical and environmental evaluation of co-
    firing tests conducted at the Maryland Correctional Institute (MCI) power
    plant in Hagerstown, Maryland, and at the General Electric Plant in Erie,
    Pennsylvania. The dRDF used in these tests were pellets prepared by the
    National Center for Resource Recovery (NCRR) and Teledyne under parallel
    contracts. The following discussion presents the results from the Phase 1
    test.
    TEST OBJECTIVE
    The objective of the study was to determine, characterize, and demonstrate
    the technical, economic, and environmental feasibility of combusting dRDF
    with coal in spreader stoker-fired boilers. The study was to specifically
    address the fuel handling, boiler performance, and environmental effects
    when dRDF pellets, cubettes, and briquettes were fired with coal in boilers
    rated at 11,300 to 90,400 kg/hr.
    SITE SELECTION
    The Phase 1 testing was conducted at the State of Maryland Correctional
    Institute for Men, located near Hagerstown, Maryland. The boiler plant
    consists of a battery of three saturated steam 150-psig Erie City boilers.
    The testing was carried out on two Erie City boilers rated at 27,200 and
    35,600 kg/hr (60,000 and 78,500 lb/hr). The boilers were equipped with
    Hoffman Combustion Engineering "under throw" spreader stokers, vibrating
    grates with front ash discharge. The Erie City boilers are a tube-and-cile
    construction co-posed of wide-spaced nominal 3 1/4-inch-diameter tubes that
    were later partially embedded in refractory to approximatey 8 ft above the
    grate. The gases are exhausted from the furnance through a two-drum boiler
    112
    

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    h.ink, consisting of rows of 2 1/4-i.nch-dinineter tubes, with two gns p.rscs.
    The flue jasas are cleaned in a two-stage multiclone collector. The fly
    ash gathered in the first-stage collector is reinjected into the boiler 10
    complete combustion of che fly char, and the fly ash in the sr-cond-stage
    collector is pneumatically transported to disposal. The cleaned easos are
    induced through a centrifugal fan and exhausted to a common breaching and
    stack.
    TEST DESIGN
    The test design called for the combustion of 253.5 Mg (235 tons) of d?JF
    during 236 hours of firing various bland ratios of coal:dRDF. These tests
    were conducted in a series of burns with volumetric coal:dRDF ratios of
    1:1, 1:2, and 0:1 and with test durations ranging from 20 minutes to
    132 hours. Each coal:dRDF test was preceded and followed by a coal-only
    test with duplicate conditions. The field tests involved a comprehensive
    study of (1) the material handling characteristics of dRDF, i.e., storage,
    conveying, feeding ouc of bunkers, ecc. ; (2) boiler performance, i.e.,
    grate speeds, underfire and overfire air requirements, steam production,
    spreader limitations, boiler efficiency, flame impingtmpnc, slagging,
    fouling, clinkering, combustion gas analysis, etc.; and (3) environmental
    performance, i.e., particulates, gaseous emissions, and trace organic and
    inorganic emissions.
    Since only pellatized dRDF was available, testing with cubettes and briquettes
    was not conducted. Also, because of insufficient plant stean demand, most
    of the testing had co be conducted at 30 to 55 percent boiler loads.
    TEST RESULTS
    Material Handling. Throughout the 6 months of field testing, 258.5 Mg
    285 tons) of dRDF were received, stored, and conveyed to the boiler without
    major difficulty or malfunction. At successive periods, the pellets were
    stored in tarpaulin-covered 20-yd3 drop boxes, in a warehouse, and on an
    outdoor concrete slab.
    Drop Boxes—Since the pellets were received in covered drop boxes during
    the winter, they tended to steam and eventually freeze into a solid mass.
    Minimal roading, however, broke the mass into blocks, and subsequent
    handling further reduced che blocks to individual pellets.
    'varenouse and Open Slab—Approximately 125 Mg (140 tons) of pellets were
    stored in an un'neated warehouse for 2 months. With the exception of mild
    offensive odors and some fungus growth, this storage proved co be the most
    effective in maintaining pellec integrity over extended periods of storage
    time. Since the depth of the piles was limited to 1.3 a (5 ft), increases
    in tamperature due to composting effects were negligible, and the pile
    stabilized at 60°C (1^0°F). The pellets stored in the warehouse were
    subsequently moved to an outdoor storage area. The pellets were stored in
    l.S-a (6-ft) piles on an outdoor slab and covered with a tarpaulin. Moisture
    accumulation under the tarpaulin caused pellets at the top of the piles to
    deteriorate and cake. Also, some pellets sustained minor damage, i.e.,
    swelling and roughened edges, because of water infiltration due to poor
    drainage.
    Pellet Feeding—The pellets were conveyed to the boiler feed hopper by a
    temporary fuel blending and handling system. The coal and dRDF were
    volumetrically blended in the various ratios by separately feeding coal ana
    pellets from two hoppers to a common bucket elevator which subsequently
    conveyed both coal and pellets to a weigh lorry. The fuels were accurately
    blended by filling che feed conveyors to capacity (level with the conveyor
    113
    

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    flights) and operating the feed conveyors at speeds coircmtnsurate with the
    desired blend ratio. Although this feeding system generally worked well, it
    had some difficulties with deteriorated pellets. As the amount of fines
    increased, the pellets would not flow from the feed hoppers without redding.
    These fines also caused considerable dusting throughout the p]ant. This
    dusting was subsequently controlled by installing a stcjani jet at the con-
    veyor transfer point.
    Pellet Properties—The 1/2- x 3/4-inch pellets had an average bulk density
    of 425 kg/m3 (26.5 lb/ft3) and ranged from 400 to 466 kg/m3 (25 no 29 lb/ft3).
    The material density for intact pellets ranged from 1.22 to 1.34 g/cm3
    while that for deteriorated pellets averaged 0.98 g/cm3. The as-reccived
    properties were 12.10 to 15.12 MJ/kg (5200 to 6500 Btu/lb), 20 to 29 percent
    ash, 9 to 10 percent fixed carbon, 12 to 13 percent moisture, 50 to 57 per-
    cent volatiles, and 1142°C to 1152°C (2088° to 2105°F) hemispheric fusion
    temperatures.
    Boiler Performance. Feeder Performance—The 1/2- x 3/4-inch pellets
    generally handled and fed well with the larger pellets traveling to the
    rear of the grate and the fines falling close to the spreader. During the
    initial combustion tests with 100 percent pellets, the spreader had to be
    adjusted to decrease the pellet trajectory by approximately 0.3 m (12 in.).
    In addition, due to volumetric feeding capacity limitations, the maximum
    load that the boiler could carry was 24,500 kg/hr (54,000 lb/hr) or 70 percent
    of rating.
    Combustion of dRJDF—The combustion of the various coal:dRDF blends was
    generally as good as the combustion of coal only. However, when the dRDF
    substition was increased, the height, intensity, volume, and violence of
    the fireball increased correspondingly.
    When test firing the 1:1 blend and 100 percent aRDF, the fireball was kept
    well away from the walls of the furnace by adjusting the overfire air.
    Once these jets were adjusted for minimum smoke and maximum efficiency for
    coal-only burning, they continued to meet the mixing and wall protection
    requirements when burning blends and 100 percent pellets. As viewed from
    the side of the furnace when firing both pellets and blends, the bed was
    well burned out by the time it approached the front ash pit. The flame
    pattern above the grate indicated that the fuel bed was maintaining proper
    porosity and that the combustion was good. With little attempt to optimize
    the system, a 10 to 12 percent carbon dioxide content in the flue gas at
    the boiler outlet was readily obtained.
    Fouling—An increase in the flue gas temperature as the boiler test progressed
    indicated that the heat transfer sections had fouled somewhat. Inspection
    of the furnace interior after the tests revealed that a light coating of
    ash had accumulated on the tubes. Also, an interim boiler inspection
    revealed that one-third of the rear wall of the boiler was covered with
    slag. This slagging was subsequently eliminated when a spreader was adjusted
    to prevent pellet impingement on the rear wall. Subsequent inspections of
    the boiler after its being on-line for 8 days revealed that the slag had
    sloughed off.
    Clinkering—During the initial tests, frequent clinkering occurred on the
    grate when firing a 1:1 blend. This clinkering was subsequently attributed
    to a low hemispheric fusion temperature, 1204°C (2200°F), of the coal.
    When the coal was changed to another coal having a higher fusion temperature,
    114
    

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    137 30C (250G°F), the clinkering stopped,
    cures clinkered, che LOO percent pellets,
    of 1151'C (2103°"), did noc clinker.
    While coal with low fusion cc-mucra-
    which had a low fusion temperature
    Corrosion—Sight clamp-on corrosion case specimens '-ere installed on che
    down-comers o: che rear screen wall 1.52 n (5 ft) above che fuel bed. After
    478 hours of exposure to various blend and coal-only firings, normal wastage
    was evident on all specimens except the 101S specimen. This test specj-en,
    which had extremely high wastage, was laouncad in the area where the heavy
    slagging occurred because of the maladjusted spreader.
    3oiler Operation. Air Flow Controllers—During load shreds, the fuel bed
    was more suscepcible co clinkering when coal:dRDF blends were fired. The
    clinkering was elinir.aced by biasing the undecfire air control co supply
    approximately 70 percenc excess air to the fuel bed. Reducing che ash
    content of the pellecs to 10 to 12 percenc should eliminate all clinkering
    problems and corresponding biasing of air controls.
    Grate Dvell-Shake—Throughout che test, che duration and amplitude of che
    grate shake pulse was adjusted to advance che fire line at the rear of the
    boiler approximately 15.2 cm (5 in.) per excitation. In all advances, the
    pulse frequency was che principal controlling variable. Ac 40 percenc load,
    the frequency of che pulse decreased from 11 minutes for 100 percent coal Co
    3 minutes for 100 percenc pellets. ^Tien firing a blend, the pulse duration
    tended to increase because che bulk density of "he blend ash was less than
    that of the coal ash.
    Ash Handling—The sieve analysis of bottom ash samples caken during coal-
    only, bland, and pellec-only firings indicated that conventional pneumatic
    ash handling systems can handle the bottom ash from blend firings as well as
    they do the bottom ash from coal-only firings. On a few occasions fire
    occurred in che ash pit during blend firing. Rodding of che clinkers
    revealed that the ash had a soft, pliable consistency. Under similar
    conditions, when firing coal only, che bottom ash was much easier co break
    up by rodding. The bottom ash removal system malfunctioned only during
    100 percent pellet firing. The bottom ash was so fine that it would noc de-
    entrain properly in the cyclone. These particles, which had been wected by
    che steam in che ejector, passed chrou§n che chroat of che cyclone and
    eventually plugged che ejector.
    As dRDF was substituted for coal, che ash distribution became finer. The
    size of the collector particles ranged from 200 micrometers for 100 percent
    coal firing to 90 micrometers (sizes ac the 50th percentile) for 100 percenc
    pellet firing. .Also, the carbon concent of che fly ash decreased signifi-
    cantly with increasing dRDF substitution.
    Mass Balance—The mass balance indicated that an unusually large amount of
    the fuel ash had accumulated in the collectors. Subsequent analysis of che
    collector fly ash revealed that the high collector ash weights were cue co
    che presence of 50 co 70 percent carbon in the ash and that 90 percent of
    che particles were greater than 50 micrometers in diamecar. The carbon
    content of the bottom ash was 2 co 10 percent, and che carbon content of che
    fly ash was 30 to 40 percent. The analysis of the fly ash as a function of
    blend revealed chat its carbon content decreased as the cRDF substitution
    increased.
    Ifficiencies--During the testing, the boiler efficiencies were extremely
    low, namely 52 co 60 percent. These low efficiencies were primarily due co
    the low boiler loses (less than 30 percent of rating) and extremely high
    115
    

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    losses (up to 25 perccnc) of combustibles in the refuse. The analysis of
    the results indicated that the coal-only and blend firing efficiencies had
    no discernable differences. However, this fact is unique to the boiler
    installation at MCI since the large amount of unburned combustibles removed
    by the collectors is certainly an anomally to expected boiler performance.
    Tables 1 and 2 present the results of the mass and energy
    balances,
    
    TABLE 1. HEAT BALANCE
    SUMMARY
    
    
    
    As Received
    
    Blend 1:0
    1:1
    1:2
    0:1
    PARAMETER
    
    
    
    Fraction of Rating .17
    .33
    .30
    .19
    Excess Air(%) 104
    82
    99
    113
    LOSSES
    
    
    
    Dry Gas 17.9
    13.7
    17.8
    19.4
    Fuel Moisture .1
    .9
    1.2
    4.0
    H20 for H2 Combustion 4.0
    5.1
    5.4
    8.1
    Combustibles in Refuse 18.3
    25.3
    16.6
    3.0
    Radiation 3.7
    1.8
    1.8
    3.7
    Unmeasured 1.5
    1.5
    1.5
    1.5
    TOTAL 45.5
    48.3
    44.1
    39.7
    EFFICIENCY 54.5
    51.7
    55.9
    60.3
    TABLE 2. ASH MASS BALANCE
    
    
    
    
    Bottom
    Ash
    Fly Ash
    Collec tor*
    
    Fuel
    %
    Ash in
    Kg/h
    r
    Kg/hr
    Kg/h
    r
    Blend
    Flow
    Ash in
    Fuel
    Carbon
    With
    Carbon
    With
    Carbon
    With
    Coal:dRDF
    Kg/hr
    Fuel
    Kg/hr
    Free
    Carbon
    Free
    Carbon
    Free
    Carbon
    1:0
    872
    21.9
    191
    82
    89
    5
    r-»
    r—
    104
    219
    1:1
    1489
    23.3
    347
    232
    238
    5
    6.8
    110
    369
    1:2
    2035
    23.4
    476
    324
    341
    7
    10.2
    145
    300
    *Note: The collector weight was determined by difference.
    Particulate Emissions. Mass Flux—The particulate mass flux in the 1:1 and
    1:2 blend firings was slightly less than the flux in the coal-only firing.
    However, the reductions were not significant at the 90 percent confidence
    level. The mass flux at a 40 percent boiler load for 1:1 and 1:2 blend
    firings was 0.5 g/Nm3.
    Particulate Size—As more dRDF was substituted for coal, the particulate
    diameter decreased. In the May tests the diameters for the coal-only
    firings were 3 micrometers and those for the dRDF-only firings were
    0.8 micrometer (at the 50 percentile point).
    Particulate Resistivity—Because of the unusually high carbon content in the
    fly ash during the coal-only firing, the resistivity was generally less than
    10° ohm-cm. As dRDF was substituted for coal, the carbon burnout in the fly
    ash improved and the resistivity increased to 2 * 1010 ohm-cm for the
    1:1 blend firing.
    Opacity—As dRDF was substituted for coal, the overall opacity of the plume
    reduced signigicantly. At 40 percent boiler load, the opacity for coal-only
    116
    

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    firing was 16 percent (based on a 1.22 a (4 ft) diameter stack). Ac che sane
    boiler load, the opacicy dropped to 10 percent for aRDF-only firing.
    Gaseous Emissions. S03--Since che dRDF had a sulfur content of 0.6 percent,
    the SOj emissions reduced with increasing dRDF substitution. The decrease
    was particularly significant for the 1:2 and 0:1 (100 percenc dRDF) blend
    firings. Ac 40 percenc boiler load, che S02 dropped from 1300 pom for coal-
    only firing to 250 ppra for aRDF-only firing.
    N0X—There '-ere no significant changes in N0X as dRDF was su'oscicuced for
    coal. Ac 40 percenc boiler load, che NOx concentrations ranged from 200 co
    350 ppm.
    Chlorine—As dRDF '-as substituted for coal, che chlorine in the emissions
    increased from 60 ppra for coal-only firing Co 650 ppm for aRDF-only firing.
    As the boiler loads changed, che chlorine concentrations differed negligibly.
    Fluorine—Fluorine concentrations also increased with increasing dRDF substi-
    tution. However, the concentrations were very low, e.g., 3 pom for coal-
    only firing and 12 ppm for dRDF-only firing at a 40 percent boiler load.
    Hydrocarbons—There were no significant changes -in hydrocarbon emissions
    when substituting dRDF for coal. Ac .a 40 percent boiler load, the total
    hydrocarbons ranged from 10 to 25 ppm. As the boiler load increased, the
    hydrocarbon concentrations decreased significantly.
    Organic Emissions—The overall emissions of polycyclic compounds for coal-
    only and blend firings were well below the chreshold limits proposed by che
    National Academy of Science.
    Inorganic Emissions—The analysis of che fly ash for trace tnecals revealed
    chac relacive co coal-only firing che blend firing enriched some cecals buc
    reduced ochers. For example, 34 times more lead was emitted when firing che
    1:2 blend 'than when firing coal only. While dRDF was the main contributor
    of 3r, MM, ?b ,• and Sb, coal was che primary source of As, Ni, and V.
    Several elements, particularly As, Ga, Ma, and Sb, tended co concencraCe in
    small particles. In addition, as the dRDF su'oscicucion increased, boch che
    solubility of the fly and che amounc of small-size particulates in che
    raspiracory range increased. Consequently, che combined effects of che
    foregoing pose a pocencial hazard co respiracion and landfills.
    SUMMARY
    The preliminary resulcs from chese field tests indicace chac coal and dRDF
    can be co-fired ac volumetric coal:dRDF ratios up co 1:2 wich only minor
    adjustments to the boiler and fuel handling systems. The Phase 2 tasting,
    which involved co-firing 1555 Mg of pellets at boiler loads of 40, 75, and
    100 percenc and coal:dRDF volumetric blends of 1:1, 1:2, and 1:4 have been
    completed. The tests were conducted in a Babcock and Wilcox spreader stoker
    fired boiler rated at 68,000 kg/hr (150,000 lb/hr), 4312 PA (625 psi), and
    440°C (325°F). Emissions tests were carried out to determine the effects of
    blend firing on electrostatic precipitator performance with and without fly
    ash injection. Results from this evaluation will be available in the near
    future. The long-term effects of corrosion and erosion cn boiler tubes when
    firing blends of coal:dRDF remains to be determined.
    117
    

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    CO-FIRING FLUFF RDF AND COAL IN A CEMENT KILN
    Cliff R. Willey
    Maryland Environmental Service
    Maryland Department of Natural Resources
    60 West Street
    Annapolis, MD 21401
    Prepared for the Conference
    "Waste-to-Energy Update 1980"
    Cincinnati, OH
    April 15-16, 1980
    118
    

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    Co-Firing Fluff RDF and Coal in a Cement Kiln
    Cliff R. Wiley
    Fluff RDF from the 3altimore County, Maryland Resource Recovery
    Facility was successfully tested as a supplemental fuel with pulverized
    coal at the Lehigh Portland Cement Company, Union Bridge, Maryland. A
    total of 1400 tons of RDF was burned in a 700 ton-per-day (clinker
    capacity) rotary kiln, contributing 30 percent of the kiln heat. There
    were four days of preliminary RDF burns followed by a 27-day extended
    period of which 20 days involved burning RDF. Tests included air
    emissions, cement quality and chemistry, RDF characteristics, and checks
    on kiln operation.
    Satisfactory Type I cement clinker was produced during most test3.
    Evidence of reducing conditions on the kiln bed due to incomplete
    burning of RDF in suspension was detected during initial tests; this
    problem, however, was quickly corrected by increasing RDF velocity into
    the kiln. Finely shredded RDF (roughly 95 percent less than one-inch
    size) was required to guarantee suspension burning. The average heat
    value of the RDF during the tests was approximately 6,500 3TU per pound.
    So adjustment in kiln raw materials feed was required when burning RDF.
    In general, particulate and chloride emissions were higher during
    RDF burning, and S0X lower. Equipment configuration was such that only
    stack emissions could be measured; therefore, the effect of burning RDF
    on kiln emissions, versus effect on electrostatic precipitator efficiency,
    could not be determined. After several days of burning RDF, some difficulty
    was experienced in removing ash and cement dust from collectors in the
    electrostatic precipitator; it va3 conjectured that this problem was
    caused by a decrease in the resistiviy of airborne particles. The problem,
    however, was not considered serious as adjustments in the precipitator
    operation could be made to correct this situation.
    119
    

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    INTRODUCTION AND OVERVIEW OF TEST PROGRAM
    In early 1975, during Che construction phase of the Baltimore County
    Resource Recovery Facility (a joint venture of the Maryland Environmental
    Service^/ and Baltimore County), Teledytie National, the project's prime
    contractor, held discussions with more Chan 30 industrial firms,
    institutions, and State organizations regarding their interest in burning
    RDF to be produced at the Facility. As a result of this survey, letters
    of interest were received from a number of potential users of RDF, three
    of whom were cement companies. Of the three cement companies, attention
    was directed to the Lehigh Portland Cement Company^/ Union Bridge,
    Maryland, because of its large coal use (500 tons per day), interest in
    a test program, and shortest distance (45 miles) from the 3altimore
    County Resource Recovery Facility.
    In ensuing discussions with Lehigh it became apparent chat, even
    though there was interest in burning RDF, there were also a number of
    justified areas of concern. These included:
    a.	abilicy to supply and feed RDF continuously
    b.	firing characteristics and ability to burn RDF in suspension
    c.	effect of RDF chemical composition and variations in
    composition on cement quality and chemistry.
    d.	long-term effects of RDF on kiln operation and cement production
    e.	effect on air emissions
    A test program was therefore developed Co tackle chese concerns step
    by step, as follows:
    (1) It was agreed that RDF would first be tasted at a
    coal-fired, Lehigh-owned, lightweight shale kiln at
    Woodsboro, Maryland. The advantage of this test
    would be that experience could be gained with the
    1/ A non-profit, waste management utility - an agency of the State of
    Maryland
    2/ Now a division of Heidelberg Cement Inc.
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    burning characteristics of RDF and the reliability
    of RDF feed equipment without facing concerns
    about cement quality and production. As part or
    the test, it was also agreed that the feed
    equipment would provide seven days of continuous
    operation before permission would be given to
    begin tests at the cement plane.
    (2)	Provided there was satisfaction with the light-
    weight aggregate test, RDF feed equipment would
    be sec up at the Union Bridge cement plant to
    produce test quantities of cement for analysis
    (a 2 to 3 day test).
    (3)	Again based on satisfaction with the previous
    step, an extended burn test involving air emission
    measurements would be run.
    Step (1) was carried out in 1977 and 1978 and Steps (2) and (3) in
    March and November-December of 1979, respectively. This paper summarizes
    results of these tests.
    The test program was carried out by Teledyne National under contract
    to the Maryland Environmental Service. Support for the program was
    received from grants to the Maryland Environmental Service by the U.S.
    Environmental Protection Agency and other sources, as recognized in
    the Acknowledgment of this paper.
    THE CEMENT INDUSTRY
    Cement manufacturing presents an attractive opportunity for
    energy recovery from solid waste via the RDF approach. It is energy
    intensive, consuming 457 trillion 3TU per year(l)£/ and it involves
    a process in which ash as well as other products of combustion become
    part of the final product, thus minimizing residues requiring disposal
    and need for costly additional air emission control equipment.
    Duckett and Weiss(2) have reviewed the potential of this RDF market,
    reporting that of L57 U.S. plants, 65 would have a capacity for 210 to
    380 tons of RDF per day, 29 a capacity for 380 to 540 tons per day and
    3/ Numbers in parentheses denote references.
    121
    

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    20 planes, over 540 cons per day when burning RDF as 30 percent of their
    fuel supply, assuming 5500 BTU/lb. RDF and 300 operating days per year.
    In addition, they point out that 26 plants are located within 25 miles
    of major metropolitan areas. In spite of this attractiveness, progress
    towards the use of RDF in che cement industry has been tempered by
    industry caucion on one side and a lack of test information on the
    other.
    Cement manufacturing typically consists of the following steps:
    (1)	grinding and mixing raw materials in wet or dry form
    (limestone, shale and/or clay, silicone oxide and
    iron bearing materials)
    (2)	drying (primarily for che wet process)
    (3)	calcining (to burn off carbon dioxide from limestone)
    (4)	clinkering (or burning), a process that cakes place at
    2,400 to 2,800°F (1,300 to 1,500s C)
    (5)	cooling, clinker grinding and addition of gypsum to
    retard setting time
    Although most new cement plants use a mora energy efficient preheated,
    dry-process system in which only step 4, clinkering, is carried out
    in the rotary kiln, 80 percent of existing plants still perform steps 2
    through 4 in the rotary kiln(l). In this process, Steps 2, 3 and 4
    occur in succession as raw materials from Step 1 are placed in one end of
    the kiln and travel counter to the flow of heat and gases from fuel burned
    at che opposice end. The process requires careful control of both
    temperature and composition, which is adjusted to account for the ash
    of fuels used to fire the kiln.
    At the end of 1978, 63 percent of cement was produced with coal
    or coke-fired plants, 20 percent with natural gas, and the remainder
    with ocher energy sources. The trend in cement production is towards
    coal-fired plants (1).
    122
    

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    TEST KILN
    The Lehigh Portland Cement Company Union Bridge plane operates four
    parallel 400-ft. (121-m), 11-1/2-ft. (3.5-m) diamecer, dry-process kilns,
    each rated at 700 tons per day capacity clinker production. The Mo. 4
    kiln was selected as the cest kiln. Characteristics of the kiln are as
    follows:
    a)	kiln inclination - 5/8-inch (1.6-cm) per linear feet;
    b)	rotation - 65 to 85 rph;
    c)	fuel - bituminous Pennsylvania-type coal (12,000 BTU/lb.
    and 2-1/2 - 3 percent sulfur);
    d)	fuel input - 6 cons per hour at 28 - 30 tons/hr. product
    throughput;
    e)	reaction (burning) zone temperacure - about 2,700aF (1,480°C).
    Air pollution control equipment on the test kiln (No. 4) consists
    of two parallel Buell electrostatic precipitators (ZS?). Total flow
    rate through the dual unit is 120,000 ACFH at 650"? (340°C).
    Approximately 95 percent of Che ES? collected¦particles (ash and raw
    material dust) is reinjected back into the kiln. The precipitators
    exhaust to a common stack-
    Raw aaterial feed to Che kiln consists of approximately 90 percent
    limestone, 10 percenc shale, and small amounts of sand and iron bearing
    materials.
    To inject RDF into the test kiln, Lehigh placed a second nozzle
    extending 11 feec (3.4 m) into the kiln, parallel co and under the coal
    nozzle. Placement above Che coal nozzle would have increased RDF
    suspension time, but kiln design prevented this arrangement. RDF
    was conveyed co the nozzle pneumatically with abouC 3,200 ASCFM air ac
    30 percent RDF kiln heat contribution.
    123
    

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    3ALTIM0RE COUNTY RESOURCE RECOVERY FACILITY AND RDF FEED STATION
    Figure 1 shows che fluff RDF process line of the Baltimore County
    facility as it now exists. Additional details on the facility and other
    recovered materials are found in References 3, 4 and 5. Daily average
    input to the facility is 750 tons residential solid waste per day. The
    RDF production line has a capacity to produce about 300 tons per day RDF
    under normal operating hours (10 hour day).
    The 800 hp Williams secondary shredder was installed in October
    of 1979; prior to that, secondary shredding was done with a 350 hp
    Grundler horizontal hammermill. Approximate particle size distribution
    of RDF for each of the shredders is given in Table 1. (This will change
    somewhat with hammer wear and solid waste characteristics.) The
    Grundler was fitted with a 1-inch round hole grate.
    TABLE 1. RDF PARTICLE SIZE (NEW HAMMERS)
    Screen Size		Z Passing	
    inch centimeter	Grundler	Williams
    3	7.6	100	99
    2	5.0	100	98.5
    1	2.5	95	94
    1/2	1.3	51	84
    3/8	1.0	17	57
    In connection with the cement kiln tests, an evaluation was done
    of secondary shredding to enhance RDF as a fuel for cement kilns;
    this work is discussed in Reference 6.
    124
    

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    FIGURE 1. PROCESS FLOW FOR RJDF PREPARATION - BALTIMORE COUNTY FACILITY
    PRIMARY SHREDDERS
    (tvo 1000 hp A-60 Tracor Marksman
    horizontal hammeraills, 6 x 12-inch hole graces
    V
    MAGNETICS REMOVAL
    (two Dings three-stage belt
    separators, one each shredder line)
    V
    DIVERTER
    (Option: portion of primary shredded stream
    can be diverted to Heil trailer compactor)
    •»
    AIR CLASSIFIER
    (modified Montgomery Industries, Jacksonville 31ow Pipe,
    vertical cylinder)
    ^ i
    CYCLONE AND AIR LOCK FEEDER
    *
    TROMMEL
    (Triple S 24-ft. (7.3-in), 12-fc. (3.7-m) diam. screen,
    1.25-in. (3-cm) holes)
    SECONDARY SHREDDER
    (300 hp Williams horizontal hanmeraill, 1.5 x 2.12 inch hole,
    herringbone pattern grates)
    CYCLONE AND AIR LOCK FEEDER
    Y
    TRANSFER TRAILER COMPACTOR
    125
    

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    As part of a market development program associated with the Baltimore
    County project, a modular, transportable RDF feed system was constructed
    for receiving and pneumatically conveying RDF to various potential users.
    Figure 2 outlines components of this system as modified for the cement
    kiln tests. RDF is delivered in 65 cubic yard transfer trailers from
    the Baltimore recovery faciliy and hydraulically metered into the RDF
    feed system. Feed rates are controlled at the RDF feed module.
    FIGURE 2. RDF FEED STATION
    TRANSFER TRAILER 
    -------
    LIGHT AGGREGATE KILN TESTS
    Prior to conducting currant kiln casts, che reliability of RDF
    feed equipment and burn characteristics of the RDF were demonstrated
    for Lehigh at a nearby plant producing a lightweight aggregate from shale.
    The advantage to this was chat It was unlikely RDF would affect the
    quality of the aggregate.
    At this plant, shale is heated and expanded in two 10-foot-diameter,
    pulverized coal-fired rotary kilns. A.nozzle to inject RDF was added
    to one kiln, next the the coal nozzle, and was connected via pipe Co
    Che feed station set up outside, next to the kiln.
    During February and March of 1977, 217 tons of RDF were burned
    intermittently. Although there were initial problems with temperature
    readings and shale buildup on the kiln wall, called "rings," these were
    overcome by adjustments in the RDF nozzle position and in the kiln
    controls. It was apparent in these Cest3 that rather finely shredded
    RDF would probably be necessary to prevent the burning of RDF directly
    on the kiln bed (grate sizes 4 to 1/2-in. were tried).
    The RDF feed system (which differed from that in Figure 2 in chat
    secondary shredding wa3 carried out at che kiln sice, wich RDF being
    aspirated from the shredder and blown into che kiln chroug'n a 12,000 C7M
    fan) did not prove reliable. Problems encountered were severe shredder
    hammer wear and maintenance, jamming, uneven feed rates, and excess air
    being blown into che kiln. Because of che inabilicy co feed RDF
    satisfactorily with this system, modifications were made co che feed
    system, bringing it into che configuration shown in Figure 2.
    In October of 1978, using the modified equipment, cests were run
    again at the kiln, sustaining an average RDF feed race of 1.13 cons per
    hour, earning che permission of Lehigh co move che RDF feed station to
    the Union Bridge cement plant.
    

    -------
    PRELIMINARY CEMENT KILN TESTS
    The object of this test was to produce initial quantities of cement
    clinker for analysis by Lehigh and by the Portland Cement Association
    and to make any necessary RDF feed equipment adjustments. Tests were
    run March 6 to March 9, 1979 and on April 26, 1979.
    During the first test, 123 tons of RDF and 215 tons of coal were
    burned in 55 hours of operation. The average heat contribution of the
    RDF during this period was 24.7 percent. Cement clinker was sampled at
    0, 10 and 30 percent RDF heat substitution.
    During the tests, 13 transfer trailer loads of RDF were used. As
    each truck was unloaded, a composite sample was taken for analysis for
    heat value, percent moisture, and percent ash, according to ASTM procedures
    D2015-71, D3302-74, and D3174-73, respectively. Results of these tests
    are listed in Table 2.
    TABLE 2. CHARACTERISTICS OF RDF - PRELIMINARY TEST
    Characteristic and Unit	Average Values3/	Low	High
    Heat Value, BTU/lb.	6897	5963	7832
    Moisture, %	18.2	12.1	25.2
    Ash, 7.	9.7	6.3	15.1
    Metallic Aluminum, 1	0.018	<0.01	0.04
    Sulfur, %	0.19	—	—
    f/Arithmetic average of 13 RDF samples except sulfur, which was run on a
    composite of all samples
    Samples of clinker and cement were analyzed by PCA by x-ray
    fluorescence, x-ray diffraction, microscopic observation, and standard
    ASTM C-130 cement tests. Partial data are included as Table 3 for
    128
    

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    reference by chose familiar wich cemenc chemistry and tests. From the
    analysis, ?CA developed the following conclusions:
    "The arnouncs of heavy metals found in che clinker vera very low
    and ic does not appear that chese elements will cause problems
    in praccice. Mo certain estimate of metallic aluminum could be
    made, buc ic seems likely chac its concentration was negligible.
    The RDF clinkers were of poor quality, mainly because of poor
    control in che burning zone of che kiln. The burning zone should
    always be maintained in an oxidizing state (at least 1 percent
    excess oxygen) and none of the RDF should be allowed to fall into
    the clinker before being thoroughly burned. If che burning
    conditions are improved, ic seems to us chat good quality clinker
    will result."
    TABLE 3. CEMENT CHARACTERISTICS FROM PRELIMINARY RDF TEST
    PERCENT RDF
    Characteristics	0	10	30
    Compressive Strength
    3-day	3820	3620	4000
    7-day	4650	4830	4370
    28-day	5920	6200	5300
    K20	0.69	0.72	0.90
    Na20	0.06	0.11	0.14
    t^O Equiv.	0.51	0.58	0.73
    Free CaO	2.14	1.13	0.95
    Although kiln operators were pleased with the testing and overall
    control of RDF, there was concern about excess RDF burning on the kiln bed
    ac che 30 percent rate, which caused reducing conditions, as noted in the
    ?CA analysis. Because of this condition, nozzle size was reduced from
    9 co 7 inches in diamecer to increase RDF velocity and suspension cime.
    129
    

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    As a follow up co Che previous cesc, a one-day run was made on
    April 26, in which 34.6 cons of RDF was burned. The smaller nozzle
    increased suspension cime sufficiently Co minimize RDF burning on Che
    clinker bed. In addicion co cescs ac 30 percenc, short runs were made
    at 40 and 50 percenc RDF heat contribution. At 40 percent, RDF also
    appeared to bum satisfactorily in suspension. However, at 50 percent
    there was dropout and flaming pieces on Che bed and decreased visibility
    into che kiln. Since a few hours of operacion is not enough co stabilize
    for clinker testing because of the slow redistribution of ash chroughouc
    the kiln and electrostatic precipitator system, no cement analysis was
    done.
    Following chese tests, permission was received from Lehigh to
    proceed with the extended cement kiln tests.
    To allow cine for installation of a larger shredder for secondary
    RDF shredding and for equipment repairs at Lehigh, not related co the tests
    but affecting them, further tescing was deferred until che fall of 1979.
    EXTENDED RDF CEMENT KILN TEST
    This test was run November 27 to December 23, 1979, burning 1,272
    tons of RDF for an average race heat contribution of 30 percent
    (approximately 3.5 tons per hour). Average characteristics of RDF used
    in the tests are listed in Table 4. Table 5 summarizes coal usage and
    RDF heat input during this period. There were 20 days on which RDF was
    burned. During December 7 to 11 che kiln was on coal only for che emissions
    testing program.
    130
    

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    TABLE 4. CHARACTERISTICS OF RDF - EXTENDED TEST
    Characteristics ana Unit
    Average Values f/
    Low
    Heat Value, BTU/lb
    6440
    5067 8797
    Moisture, Z
    20.4
    6.7 39.0
    Ash, %
    11.8
    6.4 27.7
    a/ Arithmetic mean of 95 RDF samples
    During December 5 though 14, the Environmental Engineering Division
    of the Energy System Group of TRW, Inc., conducted source emission tests to
    determine the amount of pollutants discharged from the electrostatic
    precipitator serving the test kiln. There were seven sample periods, four
    with RDF and three with coal only. Tests included flue gas flow rates
    and stack moisture determinations, particulate matter and sulfur oxides
    emissions, nitrogen oxides emissions, chlorides (as HCL) emissions,
    stationary gas analysis, and flue opacity readings. All sampling was
    conducted through four equally spaced openings located below the top of
    the stack. No sampling could be done prior to gases entering the electrostatic
    precipitator because of the design of the system.
    Table 6 summarizes conditions during the emissions test, and Table 7
    presents part of the test data. Because of electrostatic precipitator
    failure during the first test day, December 5, that day's data have been
    omitted.
    During RDF burning, particulates were higher, chloride emissions
    increased, nitrous oxide emissions appeared lower, and, surprisingly,
    sulfur oxide emissions reached their highest levels, but remained well
    within Federal and State standards. Since the RDF, which is only 0.2% in
    sulfur, significantly lowered the overall sulfur content of the kiln
    131
    

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    fuel, the increase must have been related to some other changing condition
    within the kiln or ESP. It was suggested that cleaning the ESP of dust,
    which adsorbs SO2 and is recycled back into the kiln, prior to the tests,
    may have produced this effect.
    As of Che date of preparation of this paper, complete anal/sis of
    the cement is not available from PCA. However, we have been told by
    Lehigh chat cement strength tests and other analysis so far show a
    satisfactory Type I cement was produced and indicate that the RDF fuel
    had no detrimental effects on the cement.
    Although there was an Lnitial concern by Lehigh that the raw material
    feed to the kiln would need adjustment to compensate for differences
    between the"'chemical composition of R.DF/coal ash and the coal-only ash
    it replaced, this did not turn out to be the case. Therefore, to from
    coal-only to coal-plus-RDF firing required few operational changes.
    TABLE
    5. COAL AND
    RDF USAGE DURING
    NOVEMBER - DECEMBER
    TESTS
    Date
    Coal Usage
    RDF Usa?e
    
    % Heat
    
    Daily Totals
    Daily Totals
    Total Heat Contribution
    
    (Tons)
    (Tons)
    (Million 3TU)
    (RDF)
    11-27
    72.70
    61.5
    799.5
    31.17
    11-28
    72.85
    59.0
    767.0
    30.78
    11-29
    106.0
    92.3
    1199.9
    32.35
    11-30
    42.55
    31.8
    413.4
    29.10
    12-1
    105.95
    74.2
    964.6
    27.78
    12-2
    99.10
    68.5
    390.5
    27.51
    12-4
    87.35
    63.0
    819.0
    28.37
    12-5
    106.00
    82.2
    1068.6
    29.37
    12-6
    89.20
    70.3
    913.9
    30.21
    12-11*
    30.30
    20.5
    266.5
    25.96
    12-12
    32.60
    26.7
    347.1
    30.14
    12-13
    105.30
    91.5
    1189.5
    31.40
    12-14
    104.20
    90.7
    1179.1
    31.43
    12-15
    105.95
    90.7
    1179.1
    31.11
    12-16
    109.30
    90.9
    1181.7
    30.46
    12-17
    103.35
    74.1
    963.3
    27.32
    12-18
    84.55
    63.2
    821.6
    28.25
    12-19
    43.85
    41.7
    542.1
    33.37
    12-20
    26.15
    25.5
    331.5
    33.93
    12-23
    44.50
    53.7
    698.1
    38.6
    TOTAL
    1721.4
    1397.1
    18,162.3
    30.53
    *Coal only
    for emissions
    testing 12-7 co
    12-10
    
    132
    

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    TABLE 6. OPERATING CONDITIONS AND FUEL FEED DURING EMISSIONS TEST RUNS
    TEST RUN NO.
    
    2
    3
    4
    5
    6
    7
    Date
    12/10
    12/10
    12/11
    12/13
    12/13
    12/14
    Tasc Time, scare
    end
    0913
    1131
    1211
    1426
    0950
    1206
    0840
    1049
    1412
    1624
    0801
    1026
    Product Race, cort/hr
    29.2
    29.4
    28.9
    25.1
    27.1
    29.2
    Kiln, RPM
    34
    84
    82
    71
    78
    32
    Coal Fuel Race, #/hr
    12,200
    12,770
    11,800
    3,600
    3,430
    8,500
    Coal Fuel Type*
    r/h-v
    H-V
    H-V
    H-V
    H-V
    H-V
    RDF Fuel Rate, ->l/hr
    0
    0
    0
    7,209
    9,366
    7,963
    7. RDF by 3TU Value
    0
    0
    0
    30.6
    37.4
    33.0
    Kila, Oxygen, Z
    3.2
    2.8
    2.6
    3.0
    2.3
    3.0
    Xiln End Vacer Spray
    (Gallons Per Miauce)
    26
    26
    23
    31
    34
    30
    *R 3 Regular, H-V =» High
    Volatile
    Coal
    
    
    
    
    133
    

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    TABLE 7. CEMENT KILN EMISSIONS -
    CONDITIONS STATED IN TABLE 6
    TEST RUM
    
    2
    3
    4
    5
    6
    7
    Flue Gas
    
    
    
    
    
    
    Temperature, °F
    485
    486
    483
    485
    500
    493
    Flow race, DSCFM
    49,150
    53,390
    50,190
    45,680
    49,340
    43,760
    Water vapor, by volume
    15.05
    14.60
    13.47
    19.32
    19.33
    20.95
    Stack opacity, %
    2.6
    17.0
    9.8
    21.6
    16.8
    16.6
    Particulate Matter
    
    
    
    
    
    
    Concentration, grain/DSCF
    0.0128
    0.0221
    0.0331
    0.0474
    0.0801
    0.0495
    Emission rate, pounds per hour
    5.38
    10.12
    14.26
    18.56
    33.83
    18.56
    Chloride Emissions as HC1
    
    
    
    
    
    
    HC1, pom (dry)
    7.47
    191.
    77.8
    155.
    223.
    242.
    , pounds per hour
    2.09
    58.0
    22.2
    40.3
    62.6
    60.2
    Sulfur Oxides Emissions
    
    
    
    
    
    
    SO3, pnra (dry)
    3.0
    2.5
    9.3
    4.1
    25.4
    7.1
    , pounds per hour
    1.83
    1.65
    5.79
    2.32
    15. 5
    3.85
    S02, ppm (dry)
    19.7
    34.3
    . 235
    1,050.
    353.
    444.
    , pounds per hour
    9.65
    18.3
    118.
    478.
    ' 174.
    194.
    Nitrogen Oxides Emissions (as NO?)
    
    
    
    
    
    
    N0X, ppm (dry)
    135
    295
    112
    72
    130
    160
    , pounds per hour
    47.6
    113.
    40.3
    23.6
    46.0
    50.2
    Stationary Gas Analysis (dry)
    
    
    
    
    
    
    CO2, ?.
    10.7
    10.1
    14.2
    11.4
    11.6
    12.6
    0-?, %
    13 .8
    13.6
    9.9
    11.1
    11.5
    11.9
    CO, %
    <0.02
    <0.02
    <0.02
    <0.02
    <0.02
    <0.02
    >?2, % by difference
    75.5
    76.3
    75.9
    77.5
    76.9
    75.5
    134
    

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    CONCLUSION
    RDF proved co be an adequate fuel for firing with coal in a
    rotary cement kiln ac races of up co ac lease 30 percent heat
    contribution, "o detrimental effects on the cement quality were noted
    once proper suspension burning of "he RDr was accomplished. Compression
    test strengths- were generally the same or higher when RDF was burned.
    ACKNOWLEDGMENT
    This work was supported by the U.S. Environmental Protection Agency,
    Grant S-30&786, "Marketing Refuse Derived Fuel," Office of Water and
    Hazardous Materials, Washington, DC, and Grant R-305613, "Refuse Derived
    Fuel as a Supplemental Fuel in Cement Kilns," Office of Research and
    Development, MERL and IERL, Cincinnati, OH, Mr. Robert Olexsey, Project
    Officer.
    Significant contributions to Che project also were made by che Lehigh
    Portland Cement Company, Teledyne National, and che Portland Cement
    Association.
    The author wishes Co thank Teledyne and Lehigh for "heir review and
    helpful comments in che preparation of this paper.
    Air emission casts were performed by TRW, Environmental Engineering
    Division, Research Triangle Park, NC; RDF and coal analysis was performed
    by Panniman and Browne, Inc., Baltimore, MD.
    REFERENCES
    L Portland Cement Association, "1973 Energy Report U.S. Portland
    Cemenc Industry," Skokie, IL 60077.
    2	Duckect, E.J., and Weiss, D., "The Use of RDF as a Kiln Fuel."
    In press for ASME National Solid Waste Processing Conference,
    Washington, DC, May 11-14, 1980.
    3	Willey, C.R., and 3assin, M., "The Maryland Environmental Service/
    Baltimore County Resoure Recovery Facility," Proceedings of che
    Sixth Mineral Waste Utilization Symposium, Chicago, IL, 1973,
    pp. 231-235.
    135
    

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    4	Bendersky, D. and Sinister, 3., "Research and Evaluation of Solid
    Wasce Processing Equipment," Municipal Solid Waste: Resource
    Recovery, Proceedings of Che Fifth Annual Research Symposium,
    Orlando, FL, 1979, pp. 77-85.
    5	Savage, G.M., et_. al_. , "Evaluacion and Performance of tiammermill
    Shredders Used in Refuse Processing," Municipal Solid Waste:
    Resource Recovery, Proceedings of the Fifth Annual Research
    Symposium, Orlando, FL, 1979, pp. 36-98.
    6	Weinberger, C.S., "Evaluacion of Secondary Shredding to Enhance
    RDF Production as Fuel for Cement Xilns - A Research Test," In
    press for ASME National Solid Waste Processing Conference,
    Washington, DC, May 11-14, 1980.
    136
    

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    STEAM PYROLYSIS OF ORGANIC WASTES AS
    A SOURCE OF CHEMICALS AND INDUSTRIAL FEEDSTOCKS
    by
    Michael J. Antal Jr.
    Department of Mechanical and Aerospace Engineering
    Princeton University
    Princeton, New Jersey 08S40
    INTRODUCTION
    Recently completed research at Princeton University and elsewhere (1-4)
    has shown biomass gasification to be a three step process:
    1.	Solid Phase Pyrolysis. At modest heating rates (l°C/min to 100°C/inin)
    biomass materials lose between 70% and 90% of their weight by pyrolysis,
    forming gaseous volatile matter and solid char. This weight loss occurs at
    temperatures below 500°C. As discussed later, very high heating rates en-
    hance volatile matter production at the expense of char formation. Recent
    Princeton publications review mechanistic and kinetic research on cellulose
    (5), lignin(6), and wood (7) pyrolysis in more detail.
    2.	Gas Phase Cracking/Reforming.of the Volatile Matter. At somewhat
    higher temperatures (600°C or more) the volatile matter evolved by the
    pyrolysis reactions (step 1) reacts in the absence of oxygen to form a
    hydrocarbon rich synthesis gas. These gas phase reactions happen very
    138
    

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    rapidly (seconds or less) and can be manipulated to favor the formation
    of various hydrocarbons (such as ethylene). Rates and products of the
    cracking reactions for volatile matter derived from cellulose, lignin, and
    wood are now becoming available in the literature (1, 3, 6, 7).
    3. Char Gasification. At even higher temperatures char gasification
    occurs by the water gas and Boudouard reactions, and simple oxidation
    and hydrogenation:
    C + H^O—>C0 +	(water gas)
    C + CO2 —^ SCO	(8oudouard)
    C + l/202->C0
    (oxi dation)
    C + o2 —*co2
    C + 2!^—(hydrogenation)
    Because pyrolysis (step 1) produces less than 30% by weight char for most
    biomass materials, the char gasification reactions (step 3) play a less
    important role in biomass gasification than steps 1 and 2. This contrasts
    with coal gasification, where char gasification plays a much more important
    role because most coals contain less than 40* by weight volatile matter.
    The following sections discuss steps 1 and 2 of the gasification
    process. This discussion assumes no free oxygen to be present in the gasi-
    fication system, since oxidative processes seem likely to destroy the
    chemical products sought by this research.
    SOLID PHASE PYROLYSIS OF PARTICULATE BIOMASS
    The work of 3roido (3), Shafizadeh (9), Lewellen (10) and others (11)
    has shown cellulose pyrolysis to be describable in terms of a competetive
    139
    

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    mechanism*.
    volatile tars (levoglucosan)
    char + low molecular weight
    volatiles
    Two pyrolysis reactions compete to consume the cellulose; however only one
    reaction produces char. The first reaction is favored by high temperatures
    and rapid heating, producing combustible volatile matter (1evoglucosan) at
    the expense of char formation. The second reaction is favored by low
    temperatures and slow heating of the cellulose. Water, CO, CO^ and char
    are the primary products of the second reaction.
    Because char is an unlikely source of chemicals (having to compete
    directly with coal), conditions which optimize the production of levoglu-
    cosan (Cg 0^, or the "monomer" of cellulose) are of interest here,
    levoglucosan (and related compounds) have been described as potentially
    important industrial intermediate chemicals (12). In addition it plays
    the role of a very reactive intermediate in the gas phase chemistry of
    biomass conversion (step 2).
    High yields of levoglucosan are obtained by rapid heating of the cellu-
    lose polymer (13, 14) and when condensation reactions (leading to the forma-
    tion of char) are minimized. Dilute phase, transport reactors minimize
    condensation reactions by permitting the (gas phase) levoglucosan molecules
    to rapidly disperse themselves in a largely non-reactive carrier gas (such
    as H^O, CO^, H^, Ar, He, etc). Thus entrained flow, flash pyrolysis
    reactors appear to be best suited for the production of large yields of the
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    reactive intermediate "1evoglucosan" from cellulose.
    A recent paper by Krieger (15) summarizes much of what is known about
    lignin pyrolysis. Detailed studies of the mechanisms and kinetics are not
    available. Char yields approximating 50* by weight are obtained when
    lignin is heated at a moderate rate (100°C/min) to 500°C in steam. Rapid
    heating reduces char formation (4).
    As discussed in the following section, the volatile matter evolved
    during lignin pyrolysis cracks rapidly in the gas phase to produce a
    hydrocarbon rich synthesis gas. This gas phase behavior of lignin volatile
    matter resembles that of the reactive intermediate 1evoglucosan, derived
    from cellulose pyrolysis. Since the monomeric phenyl propane units which
    compose lignin are joined by ether linkages (patterning to some extent the
    glucosidic linkages which tie cellulose monomer units together), rapid
    pyrolysis of lignin may result in the formation of monomeric phenyl propane
    units. These reactive gas phase intermediates could undergo higher
    temperature, gas phase pyrolysis to produce the permanent gases described
    in the following section of this paper. Although the results of some
    pyrolysis studies would seem to contradict this hypotheses (16), the
    effects of secondary gas phase reactions may have masked the formation of
    the primary intermediate molecule. Dilute phase, flash pyrolysis reactors
    minimize the effects of secondary reactions and promise to be a powerful
    tool for the study of lignin pyrolysis.
    The pyrolysis chemistry of hemicelluloses has been reviewed by Soltes
    and Elder (16). Although furan derivatives might be expected to be a pri-
    mary product of hemicellulose pyrolysis, low yields are usually observed
    relative to acetic acid. These results probably reflect the high reactivity
    141
    

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    of furfural and related molecules, which decompose rapidly by gas phase
    pyrolysis. Consequently, reactive intermediates derived from hemicellulose
    pyrolysis have not been observed. Nevertheless, results discussed in the
    following section of this paper suggest the formation of a reactive inter-
    mediate product during hemieel 1ulose pyrolysis which plays a role similar
    to that of 1evoglucosan.
    GAS PHASE CRACKING/REFORMING OF VOLATILE MATTER
    DERIVED FROM PYROLYSIS OF BIOMASS
    Siomass gasification chemistry is dominated by the role of the second-
    ary gas phase cracking reactions, which are largely independent of the solid
    phase pyrolysis reactions. A tubular quartz, plug flow reactor has been
    used at Princeton (1-3, 6, 7) for two years to study the products and rates
    of these gas phase reactions as a function of gas phase conditions (tempera-
    ture, residence time, steam dilution, etc.). Our results show that gas
    yields from cellulose can be increased by a factor of ten simply by in-
    creasing the gas phase temperature from 500°C to 700°C with a gas phase
    residence time of about 2 sec (1-3). Similarly, gas yields from Kraft
    lignin can be increased by a factor of three or more by the same variation
    in gas phase conditions (5). Table 1 lists typical product yields from
    cellulose, mannose, and kraft lignin for reactor conditions chosen to
    produce little or no condensible materials. Similar data for various woods
    will be available in the forthcoming thesis of Mr. T. Mattocks (7).
    Apparent gas phase rates of production of the major permanent gas
    products of cellulose gasification are given as Arrhenius plots in Reference
    1. Similar kinetic data for the gas phase conversion chemistry of lignin
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    is given in Reference 6. Oue to insufficient funding, kinetic data for
    hemicellulose gasification has not been obtained. However, kinetic data for
    wood conversion will be presented in Reference 7.
    TABLE 1. SELECTED GASIFICATION RESULTS FOR
    CELLULOSE, D MANNOSE AND KRAFT LIGMIN
    Cellulose 0 Mannose Kraft Lignin
    Gas Phase Reactor Temperature
    700
    750
    750°C
    Gas Phase Reactor Residence Time
    3.5
    2.0
    2.2 sec
    Sample Weight
    0.125
    0.256
    0.360 g
    Char Residue Weight
    0.012
    0.053
    0.176 g
    Tar Residue Wei ght
    0.003
    0.011
    0.052 g
    Gas Volume Produced
    84
    31
    73 ml
    Gas Heating Value
    490
    455
    579 Btu/scf
    Calorific Value of Char
    2.3
    5.8
    14.3 MM 3tu/tonne
    Calorific Value of Gases
    13.7
    5.7
    4.9 MM Btu/tonne
    Calori fic Value of Tars
    0.5
    0.9
    3.5 MM 3tu/tonne
    Carbon 3alancs
    0.96
    0.37
    0.98
    Gas Analysis (Vol %)
    
    
    
    CO
    52
    53
    34
    H2
    13
    10
    1 5
    co2
    8
    16
    13
    cha
    14
    14
    32
    C2H4
    6
    5
    4
    C2H6
    1
    1
    1
    C3HS
    0.1
    0.5
    0.7
    other
    0.9
    0.5
    0.3
    3ecause levoglucosan is known to be the major component of the volatile
    matter derived from rapidly heated cellulose pyrolyzate, the large increase
    in gas yields due to increasing gas phase temperatures may be presumed to be
    the result of the gas phase pyrolysis of the reactive intermediate levoglu-
    cosan. Similarly, the large increase in gas yields from lignin must be the
    143
    

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    result of the gas phase pyrolysis of some condensible material derived from
    lignin. Although the identity of this intermediate compound is not presently
    known, it may be presumed to be related to the phenyl propane units which
    compose the lignin structure. Finally, the gas phase behavior of volatile
    matter derived from mannose, wood and corn cob materials also suggests the
    formation of an intermediate compound from the pyrolysis of hemicellulose,
    which cracks in the gas phase to yield a product slate relatively similar to
    that of levoglucosar derived from cellulose.
    Somewhat surprisingly, strong similarities are evidenced between the
    product slates of cellulose, lignin and hemicellulose in Table 1 . This
    ability of thermal processes to "normalize" the conversion chemistry of
    different biomass materials is an important advantage over the more feed-
    Stock sensitive biological conversion routes.
    DISCUSSION
    Traditional feedstocks for the production of olefins (ethylene) and
    other valuable chemicals are becoming scarce and costly. For example, crude
    oil has recently been proposed as a feedstock for ethylene production by gas
    phase pyrolysis in an unusual reactor (17). An alternative source of
    ethylene is biomass: as described earlier six per cent yields of ethylene
    from cellulose and woody materials by gas phase cracking are regularly
    achieved at Princeton. With this yield, the yearly wood manufacturing
    (27x10^ dry tons), cereal straw (161x10^ dry tons), corn stalk (142x10^
    dry tons) and logging residues (75x10^ dry tons) available in the U.S.A. (13)
    could be used to produce 24x10^ tons per year of ethylene without the use
    of imported hydrocarbons. The predicted 1930 demand for ethylene in the
    144
    

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    U.S.A. is 14x10® tons. Thus, presently obtainable yields of ethylene from
    organic wastes are sufficient to meet our annual ethylene demand by the gas
    phase cracking of agricultural and wood residues.
    Olefin production also has a significant impact on process economics.
    Table 2 lists the values of various products obtained from 3razilian
    Eucalyptus Wood using a Princeton pyrolysis reactor. Reactor conditions
    weve not o-piirtizsd for sthylsns production. Nevertheless, ethylene is the
    second most valuable product. Ongoing research at Princeton could more
    than quadruple the yield of ethylene from Eucalyptus wood over that indicated
    i n Table 1 .
    CONCLUSIONS
    Flash pyrolysis of particulate biomass materials produces large yields
    of reactive intermediate compounds referred to as volatile matter. These
    intermediate compounds undergo further pyrolysis in the gas phase at some-
    what higher temperatures, producing lighter weight oxygenates and hydro-
    carbons .
    Research at Princeton has shown that yields of ethylene generally
    exceeding by weight can be produced from cellulosic materials. The
    ethylene is produced entirely by the gas phase cracking reactions. Future
    research on the gas phase cracking chemistry of organic wastes could
    potentially quadruple the yields of ethylene. The production of ethylene
    and other valued chemicals from organic wastes has the potential of
    revolutionizing the petrochemicals industry within a decade.
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    TABLE 2. ESTIMATED VALUE OF THE PYROLYSIS PRODUCTS OF
    BRAZILIAN EUCALYPTUS WOOD
    One metric ton ¦
    Eucalyptus Wood
    GdS
    -> C2Hu*
    Char
    Tar
    9 Gj at S2 .00 per Gj	= $1 8
    32 kg at $0.38 per kg	= $1 2
    6 Gj at $1 .50 per Gj	= $ 9
    1 Gj at $1 .00 per Gj	= $ 1
    total	$40
    *Y1elds of ethylene will be considerably improved in future reactor designs,
    REFERENCES
    1.	Antal, M.J. "The Effects of Residence Time, Temperature and Pressure on
    the Steam Gasification of Biomass", American Chemical Society Division
    of Petroleum Chemistry, Honolulu, 1979.
    2.	Antal, M.J. "Synthesis Gas Production from Organic Wastes by Pyrolysis/
    Steam Reforming", IGT Conference on Energy from Biomass and Wastes,
    Washington, D.C., 1978.
    3.	Antal, M.J., Friedman, H.L., Rogers, F.E. "A Study of the Steam Gasifi-
    cation of Organic Wastes", (Final Progress Report, U.S.E.P.A.)",
    Princeton University, Princeton, N.J. 1979.
    4.	Rensfelt, E., 81omkvist, G., Ekstrom, C., Engstrom, S., Espensas, S-G.,
    Liinanki, L. "Basic Gasification Studies for Development of Biomass
    Medium Btu Gasification Process", IGT Conference on Energy from 8iomass
    and Wastes, Washington, D.C., 1978.
    5.	Antal, M.J., Friedman, H.L., Rogers, F.E. "Kinetic Rates of Cellulose
    Pyrolysis in Nitrogen and Steam", to appear in Combustion Science and
    Technology, 1979.
    6.	Kothari, V.S., Antal, M.J., Reed, T.B. "A Comparison of the Gasifica-
    tion Properties of Cellulose and Lignin in Steam", to appear.
    7.	Mattocks, T. M.S.E. Thesis, Princeton University, Princeton, N.J., 1979.
    8.	Broido, A. "Kinetics of Solid Phase Cellulose Pyrolysis", in "Thermal
    Uses and Properties of Carbohydrates and Lignins", Shafizadeh, F. et al .
    (ed.), Academic Press, New York, 1976.
    9.	Shafizadeh, F., Groot, W.F. "Combustion Characteristics of Cellulosic
    Fuels" in "Thermal Uses and Properties of Carbohydrates and Lignins",
    Shafizadeh, F. et al. (ed.), Academic Press, New York, 1976.
    146
    

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    10.	Lewellen, P.C., Peters, W.A., Howard, J.3. "Cellulose Pyrolysis
    Kinetics and Char Formation Mechanisms", 16th International Symposium
    on Combustion, Cambridge, 1976.
    11.	Arseneau, O.F. Can. J. Chem., 1971, 49, 632.
    12.	Shafizadeh, F. "Thermal Conversion of Biomass" in RANNZ, Volume 2,
    NSF, 1 976.
    13.	Berkowitz-Mattuck, J.B., Noguchi , J.3. Journal of Agolied Polymer
    Sci encs, 7, 709, 1 963.
    14.	Martin, S. "Oiffusion Controlled Ignition of Cellulosic Materials by
    Intense Radiation", 10th International Symposium on Combustion,
    Cambridge, Mass. 1964.
    15.	Graef, G., Allan, G.G., Krieger, B.S. "Rapid Pyrolysis of Biomass/
    Lignin for Production of Acetylene", American Chemical Society Division
    of Petroleum Chemistry, Honolulu, 1978.
    16.	Soltes, E.J., Elder, T.I. "Pyrolysis" in "Organic Chemicals from
    Biomass", CRC Press, to appear.
    17.	Yamaguchi , F., Sakai, A., Yoshitake, M. and H. Saegura "COSMOS Cracks
    Crude to Olefins", Hydrocarbon Processing, 9_ (58), 167, 1979.
    13. Burwell, C.C. "Solar 3iomass Energy: An Overview of U.S. Potential",
    Science, 199, 1041 , 1978.
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    ENVIRONMENTAL ASSESSMENT OF w'ASTZ - TO-ENERGY
    CONVERSION SYSTEMS
    by
    K. P. Aaanch
    M. A. Golembievski
    Midwest Research Institute
    425 Volker Boulevard
    Kansas City, Missouri 54110
    EPA Contract No. 63-02-2166
    MRI Project No. 4290-G
    EPA Project Officer: Harry M. Freeman
    for
    Presentation ac the "Wasce-co-Energy Technology--rJpda te L980" Conference
    Cincinnati, Chio
    April 15-15, 19SO
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    Introduction
    The Fuels Technology Branch of Z?A13 Industrial Environmental Research
    Laboratory in Cincinnati is sponsoring a program ac Midwest Research Insticuca
    (MRI) co conduce environmental assessments or wasta-co-energy conversion facili-
    ties. The overall objective or chis program is co evaluate the multi-media
    environmental impacts chat result from using waste (municipal solid waste, in-
    dustrial/sewage sludge, agricultural residue) as an energy source and to iden-
    tify control technology needs. As part of chis program, MSI has undertaken
    fairly extensive sampling and analysis efforts at the following waste conversion
    sites.
    *	A 200 ton/day refuse pvrolysis system
    *	A 120 ton/day municipal Incinerator fired with municipal solid
    vasts (MSW)
    *	10MW power plant boiler fired with wood waste and No. 2 oil
    *	A 70,000 lb/hr 3team boiler fired with coal and densified refuse-
    derived fuel (dRDF)
    *	A 20MW power boiler fired with refuse derived fuel
    A brief description of the facility, the sampling and analysis methods used,
    and the results obtained are individually presented below for each of these
    facilities.
    Refuse ?v~olvsis System
    The Union Carbide refuse pyrolysis system (FJRQX) at South Charleston,
    West Virginia, was designed to pyrolyze 200 tons/day of refuse. The refuse was
    obtained by shredding MSV co a 3 in. size and then removing the magnecic mater-
    ials from the shredded waste. The PUROX system is a partial oxidation process
    chat uses oxygen to convert solid wastes into a gas having a higher heating
    value (ZHV) of about 370 3tu/scf.
    The refuse is fad into che cop of Che reactor, che principal unit on
    the process. There are chree general zones of reaction within the reactor (dry-
    ing, pyrolysis, ana combustion). The reactor is maintained essentially full of
    refuse which slowly descends by gravity from che drying zone through the pyroly-
    sis tone into che combustion zone. A countarflow of hoc gases, rising from the
    combustion zone at che bottom, dries the incoming moisc refuse. As che material
    progresses downward, it is pvrolyzed co form fuel gas, char, ana organic liquids
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    Oxygen is injected into the bottom hearth section ac a ratio of about
    207. by weight of incoming refuse. The oxygen reacts with char formed from che
    refuse co generate temperatures of 2500 co 3000°; in che Lower zone which con-
    verts che noncombusciblas inco a molten residue. This rasidue is discharged
    inco a water quench cank vhere it corns a slag. The cypical composition of che
    3 lag is reported to be 507. SiO-,, L17. Ai-,03, 117. CaO, 97. J^O, 57. FeO, 27. MgO,
    and 27. ocher oxides.
    The Sot gases from che hearch section are cooled as chey rise chrough
    che zones of che reactor. Aftar leaving che raactor, che gases are passed
    chrough a recirculating wacer scrubber. Entrained solids are separaced from
    che scrubber wacer in a solid-liquid separator, ana racyclad co che reactor for
    disposal. The watar product discharged from che separacor system is senc co a
    plane creataent syscem. The gas leaving che scrubber is further cleaned in an
    electrostatic precipitator and then cooled in a heat exchanger prior co combus-
    tion in a flare comoustor. For purposes of this cast program, however, che pro-
    duct gas was combusted in a package boiler and amissions resulting from its
    operation were characterized. As a baseline comparison, the source boiler was
    also tested when firad with natural gas.
    Sampling and analysis of air emissions from che boilar included parti-
    culate loading determination by EPA Method 5 with a aigh volume sampling syscam
    (HVSS), gas analysis by continuous monitors for 0?) CO, hydrocarbons and M0X.
    SQ2 was determined by EPA Method 6. Gas samples for total carbonyls were col-
    lected using grab sampling techniques and analyzed using prescribed procedures.
    In sampling for mercury and chlorides, fluorides, bromides and cyanides in the
    vapor form, a sampling crain concaining 5 midget impiagers was used. In addi-
    cion, che Source Assessment Sampling Syscam (SASS) was used as prescribed by
    EPA for Level 1 environment assessment. Opacity of scack emissions was deter -
    mined using EPA Method 9.
    The PITR0X gas fad iaco che boilar was also sampled for cricaria pol-
    lutants using EPA mechods.
    ¦ Refuse fed inco the reactor, slag from che quench cank, and wascavacer
    before and after Creacnent were all sampled and analyzed for mecals, anions, and
    PC3's. Wastewater analysis was also carried out for priority pollutancs ocher
    chan ?C3's and for BOD, COD, curbidicy, phenols, acc.
    Results of che casting effort showed that, of the criteria pollutants,
    only N0X and particulate emissions increased when burning Purox gas as compared
    to natural 2as. N0X and particulate levels were of the order of 350-400 pom and
    6-14 mg/dNm respectively. SO2 amissions averaged 70-100 ?om. Particulate and
    SO2 emissions vere below present scandards, whereas M0X will require further
    -eduction. Also, analysis for cecals and ocher pollutants indicates that these
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    should aoc present any problems. The vastevatar, however, without proper treat-
    aeac would be a aajor araa of concern.
    The SAM-LA assessment methodology vas utilised by applying it co che
    daca obtained for aach of the thrae primary affluent streams from the Jurox pro-
    cess (slag, scrubber affluent, ana boiler stack gas) . Results of this applica-
    tion showed chat che scrubber afflueac had che highest degree of hazard, being
    considerably greater than che hazard value for che inpuc river water. However,
    che slag scream had che highesc toxic discharge raca (TuDR). The boiler flue
    gas affluent had che lowesc hazard value and che lowesc TUDR; boch vera close
    Co cha baseline values computed for boiler flue gas when burning nacural gas.
    Municipal Incinerator Tired with MSV
    The Braintree municipal incinerator (3raincrae, Massachusetts) is a
    aass-burn facility consisting of tvia vacer-vall combustion units, aach with a
    design capacity of 120 tons of MSW for 24-hr period. A portion of che steam
    produced (20-357.) is supplied to neighboring manufacturers and cha remainder is
    condensed. Each furnace is equipped with an ESP ana boch ISP's exhaust co a com-
    mon stack.
    The Riley Stoker boilers ara of the single pass design with aach hav-
    ing a r3tad capacity of 30,000 lb of steam/hr at ±QQ°7 and 250/psig. The ESP
    units ara single field, 12 passage precipitators with a specific collection araa
    of 125 ft~/1000 acfa; aach has a design collection efficiency of 937..
    invtronmencal assessment of the incinerator facility was conducted
    using EPA approved sampling and analysis procedures. Results and conclusions of
    tne cesciag effort are summarized below.
    Of the critaria pollutants, S02>	a:i(i hydrocarbon amissions were
    low. However, CO levels were high and could not be explained considering the
    large quantities of excess air chac were used. The average particulate concen-
    tration was 0.24- gr/dscm, corrected co 127, CO2 • This level exceeded the faderal
    and staca regulations. However, subsequent cases for compliance had an outlet
    particulate loading o£ 0.07i jr/dscf, which shows compliance.
    Elemental analysis of che glass-and metal-free boccon ash revealed an
    overall increase in the elemental, concencracions when compared to the refuse faed.
    The coiiactad fly ash contained levels of chlorides, sulfates and some trace
    netals which nay be of concern. ?C3's were not detected in the collected fly
    ash; & PAH compounds were identified.
    Levels of 3CD,C0D, oil and grease, TS5 and TDS in the bottom ash quench
    watar do not appear to be of concern. The phenolic concant vas found co be
    <0.1 ag/liter in all samples.
    151
    

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    Levels of gaseous chlorides and ocher halides were low. Presence of
    ?C3's was confirmed only Ln the SAS5 era in XAD-2 resin ac a concentration of 3.5
    ag/n'3.
    Results of che SAM-LA environmental assessment procedure show che in-
    cinerator scack emissions co have che highest apparenc degree of health hazard.
    Further analysis is needed co determine che exact composicion of che organic
    components of che scack emissions to better ascertain the hazard potential.
    SAM-LA also shoved chac che boccom ash effluent had the largest toxic unit dis-
    charge race due primarily to che abundance of phosphorus and aiecals in this stream.
    Power Plant 3oiler Fired With vJoodwascs and Fuel Oil
    The Mo. 1 unit ac the 3urlingcon Electric Plane (Burlington, Vennonc)
    was originally a coal fired boiler which has since been aodiiied co fire wood
    chips wich supplemencary No. 2 fuel oil. Because of che high aoiscure concent
    of che chips, che boiler cannot provide che desired steam output on wood alone.
    Therefore, No. 2 fuel oil is used. Sceam produccion-is raced ac LOO,000 lb/hr,
    which powers a 10MW curbine generacor. Residual ash from che boiler is dis-
    charged ac the end of che grace inco a hopper and is then pneumatically trans-
    ported to an outdoor storage silo. The flue gases leaving the boiler are ducted
    CO an amission control, system consisting of fao high efficiency mechanical col-
    lectors in series. For a flue gas flow rate of 60,000 acfm at 330°?, che col-
    lectors were designed for an overall pressure drop of 6.5 in. H2O and a collec-
    tion efficiency of 97.75".
    Sampling and analysis was focused on che input fuels, boctom ash, pri-
    aary and secondary collector ash, and air amissions at the collector inlec and
    outlet. The input fuels were analyzed for their heating value and trace cnecal
    concenc. The aois cure concenc of wood was also decarmined. Boctom ash ana
    collector ash were analyzed for cheir trace aiecai and PC3/PAH concencs . Collector
    inlet gases were sampled using SPA Method 5 for parciculace. particle sizing and
    elemencal analysis were also carried ouc. The scack gases were sampled and
    analyzed for criteria pollutants, trace aiecals, and PC3/PAH. SPA Mechod 5 and
    5ASS trains were used for parciculace aeasuraaenc. Major resulcs and conclusions
    of the sampling and analysis program are as follows:
    On a heat input basis, wood accounted for 807« of the boiler fuel, and
    oil the remainder. The heat of combustion of wood was 5870 3tu/lb (as received)
    and for oil, the heat of combustion was 19,500 3tu/l'o.
    3octom ash analysis indicaced chac aosc elemencs were aore concentrated
    in the ash relative co che input fuels. No PC3's were dececced in boctom ash but
    one PAH compound was present at a concentration of 0.39 ug/g. Primary and secon-
    dary collector ash contained no PCB's but several PAH compounds were identified
    in the secondary ash wich one sample containing 10 ug/g of ahenanchrane.
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    Particle sizing ac the collector inlat and outlet could r.oc be estab-
    lished due co constant plugging of che dilution system. Scack concentration of
    particulates averaged 0.08 gr/dscf and che collector had a particulate efficiency
    of 9^.27.. N0X and SO? concentrations averaged 66 and 123 pon respectively. CO
    averaged 213 pom and hydrocarbons 9 pom. Analysis of Method 5 particulate indi-
    catad concancracicns approaching 100 ug/dsca for ?b, 3a, 3r, Fe and Ti in che
    scack gases. ?C3 and PAH cases of che scack gases ware negative.
    EPA'3 SAM-LA analysis indicated chac che 3accQdary collector ash con-
    tained che highest degree of hazard a 1 chough all 3 ash screams were siailar in
    che magnitude of cheir hazard values. Scack emissions snowed a low degree of
    hazard. The primary collector ash had che highest toxic unic discharge rata.
    However, because of che limitations of che methodology, chese. findings should
    30c be viewed as conclusive.
    Steam 3oilar Firad with Coal and Densifiad Refuse Derived Fuel (dRflF)
    MRr, in conjunccion wich che Geaer3l Services Adniniscracion (GSA) and
    che National Centar for Rasource Recovery (NCES) , conducted amission cases on
    ¦che No. boiler ac che GSA/Pantagon facility. The No. ^ unic was co-firad with
    difieranc blends of coal and dSDF. S caam oucpuc of che underfed-racort stoker
    boiler was rated ac 70,000 Ib/hr. The boiler was equipped wich. a mulciclone unic
    for particulaca removal.
    Emission casts vera conductad by MSI Co decarrine particulaca loadings,
    gaseous criteria pollucanc and chloride concancracions in che scack gas. The
    particulaca samples were also analyzed for lead. lasting was conducted first
    at baseline conditions (coal only as fuel) and chen when firing blends of 20%
    d&DF:S0" coal and 307. dSLDF:407. coal. NCXS. conducted other evaluations . The results
    of MSI's efforts are as follows:
    *	Particulate emissions ware raducad from 22 to 387. when d3HF was
    blended wich che original coal fuel. Filcarabla particulate emissions vera lowest
    when using che 207. dSDF blend and rosa again when che proportion of dSDF was
    raised co S07». This finding nay noc be conclusive, however, since che boiler
    load was held staady during the 207. dSDF firing but not during che 607. mode.
    *	The amounc of particulaca lead amicced when burning cLJLDF with coal
    is substantially higher than chat from combustion of coal alone (an average of
    10C0 ag/a^ wits 207. dRDF, and i^50 ug/m^ with cC/L dSDF, versus 320 ug/n^ wich coal
    only).
    - Chloride amissions showed no definite trand which could be used to
    correlate chloride amissions with RDF modes, though slightly higher concancracions
    of HC1 were observed in r-o of che samples collected during combustion of che
    507. dSDF bland.
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    Power Boiler Fired with RDF
    The Hempstead Resource Recover/ Plane (Long Island, New York) is a
    complece wasce-co-energy facilicy in chac ic cakes In municipal solid wasce, pro-
    duces an RDF and converts the fuel co eleccrical power. The facilicy consists of
    cvo discincc segmencs: a refuse processing ooeracion, utilizing che 31ack Clawson
    Eydrasposal system; and a power house, which concains cvo 5ceam. boilers aacL cvo,
    20 eleccrical curbine generacors.
    Tests were conducted by MRI on che Mo. 2 unic of che power house, which
    is an air-swepc spreader scoker wacerwall boiler wich a nominal capacicy of
    200,000 ibs/hr of sceam ac 625 psig and 750a7. The boiler was fired wich 1007,
    refuse-derived fuei (RDF), although auxiliary oil burners are used for start-up
    and during fuel feed incerrupcions. Air poliucion concrols for che boiler con-
    sisc of a bank of 12 mechanical cyclones followed by an eleccroscacic precipicacor.
    The purpose of che program was co primarily invescigate organic con-
    stituents of- che scack gases and co quanciiy odorous componencs.
    Emission screams avaluacad included che boiler boccom ash, cyclone ash,
    ES? ash and che scack effluenc gases. Samples of che RDF were also collected for
    analysis. The chree ash screams were analyzed for elemencal composition, as well
    as for ?C3 and PAH oiacarials. Scack amissions were continuously aonitorea for
    SO,,	CO, 07 and cocal hydrocarbon concencracions, and were also cesced co
    determine levels of vaporous mercury' and aldehydes. In addition, a test was con-
    ducced using che Source Assessmenc Sampling Syscen (SASS) for analysis under
    EPA's Level L protocol. Samples of che RDF fad co che boiler were avaluacad for
    moiscure concent, elemental composition and chemical parameters (proximate/ultimate
    analyses) .
    Laboracory analyses have only been partially compleced. Therefore,
    che results will be reported ac the cime of presencacion of this paper.
    154
    

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    EMISSIONS ASSESSMENT FOR
    REFUSE-DERIVED FUEL COMBUSTION
    Prepared for:
    Environmental Protection Agency
    Cincinnati, Ohio 45268
    Under Contract No. 68—03—2771
    Submitted by:
    J.W. Chrostowski
    Energy Resources Co. Inc. .
    185 Alewife Brook Parkway
    Cambridge, Massachusetts 02138
    (617) 661-3111
    March 18, 1980
    156
    

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    1. Introduction
    Energy Resources Co. Inc. (ERCO) has been contracted
    by the Environmental Protection Agency (EPA) to investigate
    the emissions (gaseous and particulate) from co-firing of
    refuse-derived fuel (RDF) and coal in a pilot-plant scale
    atmospheric fluidized-bed ccmbustor (AFBC). Gaseous
    emissions (SO.,, NO , CO, and hydrocarbons) are continuously
    fa	A
    monitored with the appropriate instrumentation. Parti-
    culates samples are collected with a Source Assessment
    Sampling System (SASS train) and will be subsequently
    analyzed for trace metals and organic content using the EPA
    Level 1 procedure.
    2.	RDF/Coal Supplies
    At the present time, two sources of RDF and a single
    source of coal have been obtained. The suppliers and
    properties of the fuels are summarized in Table 1.
    3.	Description of Work Plan
    The major objectives of this investigation are as
    follow:
    • Quantify the gaseous and particulate emissions from
    a co-fired RDF/coal feed in an atmospheric fluidized-
    bed combustor. The primary process variables include
    ¦combustion temperature (1100 - 1400° F) and the
    weight fraction of RDF in the feed (0-75 percent).
    The upper temperature limit of 1400° F is set by the
    fusion temperature of glass which is present in the
    source RDF material.
    157
    

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    TABLE 1
    COAL/RDF SUPPLIERS AND FUEL PROPERTIES
    Crushed Coal
    -FEEDSTOCK-
    EcoFuel
    Anierlcology
    Suppller
    Si ze
    Heating Value (IIIIV, Btu/lb
    m. f.)
    Moisture (% wet basis)
    Chemical Composition
    (wt %, m.f.)
    Sulfur
    Carbon
    Hydrogen
    Ni trogen
    Oxygen
    Chloride
    Ash
    Fusion Temperature (°F)
    Battelle
    233S> 1. 7nm
    59% mid-range
    18%<300|jm
    12953
    9.38
    0.07
    71.81
    1.78
    1.59
    15.5
    0.53
    Combustion
    Equipment
    Associates
    28%<170 mesh
    30% 170/230 mesh
    42% 230/325 inesh
    7827
    3.2
    0.61
    40.0
    4.6
    <.1
    45.5
    .26
    9.0
    ^1800
    American Can
    <1"
    6430
    25-35
    N. A.
    N. A.
    N.A.
    N.A.
    N.A.
    N.A.
    N.A.
    M 300
    

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    • Obtain pilot plant performance data to assess the
    suitability of co-firing RDF/coal in an atmos-
    pheric fluidizea-bed combustor. This includes
    the determination of associated heat and material
    balances to define the overall process.
    4. Description of Atmospheric Fluidized-3ed Combustor
    (AFSC) Pilot Plant
    A schematic of the ERCO AF3C pilot plant is provided
    in Figure 1. The major equipment components include the
    following:
    Solids feed system (hopper, star valve and feed
    screw)
    Sutorbilt rotary vane air blower (600 SCFM at
    6 psig discharge)
    20" diameter fluidized bed (2.13 ft^) with
    removable in-bed heat transfer tubes and ccn-
    vective heat transfer tubes in the freeboard
    Fisher-Klosterman cyclone for elutriated solids
    collection
    SASS train for particulate and organic collection
    The fluidized bed has a Incallov-300 perforated plats
    distributor which is mounted to permit thermal expansion.
    The fluidizing medium is refractory sand with a mean particle
    size of 400-500 microns diameter. The bed is heated to the
    desired ignition temperature of 300-1000° F (before the
    addition of the coal/RDF feed) by burning natural gas below
    the distributor plate.
    The continuous monitoring equipment for gaseous emissions
    include the following:
    159
    

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    Cyclone
    Convective
    Freeboard
    Tubes
    Coal/RDF
    Feed Hopper
    ln-3ed Heat
    Transfer Tubes
    Rotary V
    Star Valve
    Solids
    Feed
    Screw
    Distributor Plate
    Combustion Air
    Figure 1. Schematic of ERCO Fluidized 8ed Pilot Plant.
    160
    

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    •	Seckman Paramagnetic C>2 Analyzer
    •	Thermo-Electron Chemiluminescent MO-NO^ Analyzer
    •	Thermo-Electron Pulsed Fluorescent SO2 Analyzer
    •	Beckman NDIR Model 365 CO/CO2 Analyzer
    •	Beckman FID Model 400 Total Hydrocarbon Analyzer
    In addition to this on-line equipment, a Fischer Hamilton
    Model 120 0 Gas Partitioner is used to periodically sample for
    t t ^2' ^2' and CO2•
    5. Summary of Coal/RDF Runs
    The pilot-plant AFBC has been run with crushed coal
    (no RDF) and with two RDF/coal mixtures (25 and 50 weight
    percent EcoFuel) with bed temperatures ranging from 1000
    to 1320° F. The operating data and the heat and material
    balances for the individual runs are summarized in Table 2.
    In these runs, the static bed height was maintained
    relatively constant at 16 to 13 inches and the fluidizing
    velocity ranged from 1.1 to 3.1 feet/sec at the actual operating
    conditions. The minimum fluidization velocity for the refrac-
    tory sand with a mean particle diameter of 420 microns is
    nominally 0.29 feet/sec. Operation with a fluidizing
    velocity 3.9 to 11.1 times the minimum fluidization velocity
    ensures excellent solids mixing and uniform temperature
    distribution (+ 25° F) throughout the bed.
    It should be noted that these preliminary runs were
    shake-down runs to ensure satisfactory operation of 1) the
    pilot-plant equipment (solids feed system and bed operation);
    161
    

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    2) on-line instrumentation for SC^, ^x' CO, an<^ ^2 measure~
    ment; and 3) evaluation of the SASS train for particulate
    and organic collection.
    The data in Table 2 for runs #3-6 with crushed coal
    alone indicate satisfactory performance of the AFBC with
    combustion temperatures ranging from 1150-1313° F. The
    combustion temperature was varied by either changing the coal
    and air feedrates (maintain same excess air) or the number of
    in-bed tubes. Because of the fines in the crushed coal (18
    wt percent less than 300 microns), 20 to 30 percent of the
    carbon was burned in the freeboard. The efficacy of the SASS
    train for particulate collection was initially evaluated in
    run #6. Because of the relatively high particulate, loading
    from the cyclones, the SASS train filter clogged in approx-
    imately 30 minutes.
    The two preliminary runs with EcoFuel/coal (run #7
    with 50 percent RDF and run #3 with 25 percent RDF) at
    nominally 1300° F were successful from the standpoint of
    solids feeding and operation of the fluidizea bed. The run
    (#7) with 50 percent RDF indicated a significant amount of
    freeboard burning associated with the fine particle size of
    the RDF (42 wt percent less than 230 mesh). The SASS train
    was again evaluated in run #8 with 25 percent RDF; as before,
    the filter clogged after about 30 minutes of sampling.
    6. Future Work
    The primary objectives of the future series of RDF/coal
    runs will be the following:
    162
    

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    TABLE 2
    SUMMARY OF RDF/COAL AF3C RUNS
    RUN NUMBER
    3
    4
    5
    6
    7
    8
    Feed Rates:
    
    
    
    
    
    
    Coal/RDF (Ibs/hr)
    71
    12
    30
    30
    24
    34
    Weight Fraction RDF
    0.0
    0.0
    0.0
    0.0
    0.50
    0.25
    Air (SCFM)
    115
    71
    56
    64
    39
    59
    Fluidizing Velocity
    3.13
    1.79
    1.56
    1 .66
    1.10
    1.64
    (fps)
    
    
    
    
    
    
    Temperatures (°F)
    
    
    
    
    
    
    Bed
    1203
    1150
    1318
    1210
    1320
    1309
    Freeboard
    866
    1086
    905
    891
    1060
    868
    Stack Gas Composition
    
    
    
    
    
    
    Oxygen (%)
    1.7
    3.1
    2.9
    3.7.
    2.5
    3.2
    CO (pom)
    1055
    —
    425
    225
    530
    527
    NO (ppm)
    124
    --
    —
    —
    80
    96
    S0X (ppm)
    975
    —
    —
    —
    539
    273
    Energy Balance
    
    
    
    
    
    
    Heat Out/Heat In
    1.02
    1 .18
    1.20
    1.09
    1.01 '
    0.78
    Thermal Efficiency
    0.43
    0.73
    0,85
    0.76
    0.70
    0.50
    Combustion Efficiency
    0.64
    0.76
    0.87
    0.90
    0.93
    0.91
    Fraction C Burned in
    0.10
    0.27
    0.18
    0.20
    0.65
    0.08
    Freeboard
    163
    

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    Modify the SASS train to extend the sampling
    time from 30 minutes to permit collection of
    sufficient particulate and organic material for
    subsequent analysis.
    Run varying RDF/coal mixtures at temperatures of
    nominally 1100, 1200, and 1300° F to obtain
    gaseous emissions data. Run the SASS train with the
    optimum set of conditions to obtain particulate and
    organic emissions data. These runs will be per-
    formed with the two RDF fuels presently available,
    namely EcoFuel from CEA and the Americology fuel.
    Obtain a source of hazardous waste which can be co-
    fired with RDF to study emissions from an atmos-
    pheric fluidizea-bed boiler.
    164
    

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    KVB12-P-
    COMBUSTION AND EMISSION ASSESSMENT OF REFUSE-DERIVED
    FUEL COFIRED WITH PULVERIZED COAL
    BY
    L. J. MUZIO, Ph.D.
    J. K. ARAND
    R. R. PEASE, II
    KVB, INC.
    A Research-Cottrell Company
    for
    WASTE-TO-ENERGY TECHNOLOGY - UPDATE 1980
    Cincinnati, Ohio
    April 15-16, 1980
    166
    

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    COMBUSTION AND EMISSION ASSESSMENT 0? REFUSE-DERIVED
    FUEL COFTRED WITH PULVERIZED COAL
    INTRODUCTION
    Solid waste burning is not a new concept. Incinerators for burning municipal
    waste were formerly common in most metropolitan areas. With the passage cf
    stringent air pollution regulations and the advent ox the sanitary landfill,
    burning of garbage has lost much of its widespread application. Recently,
    however, new incentives have surfaced which make the combustion of municipal
    waste an attractive disposal alternative. Today's proposed and prototype
    waste-burning installations are processing solid waste Ln a variety of methods
    that may shred, compact, or pelletize the refuse into valuable fuel. Resources
    in the waste stream are recovered, and conservation of energy is realized by
    the use of this alternate fuel.
    A laboratory program is being conducted to measure emissions (aqueous, air,
    solid waste) from the combustion of refuse-derived fuel (RDF) and mixtures of
    RDF and coal in a suspension-fired system. Two sources of SDF will be eval-
    uated, Combustion Equipment Associates' (CEA) Eco Fuel II and Americology SDF.
    Evaluation of transformer waste oil contaminated with polychlorinated biphenyls
    (PC3) is also planned. The criteria pollutants NO, SOj, CO, and hydrocarbons
    will be monitored continuously in the flue gas stream, and special tests will
    be performed to characterize the fuel, flue gas stream, and bottom ash in terms
    of trace elements and trace organics including POM and ?C3, fluorine, chlorine,
    and bromine.
    The combustion facility used for this program is capable of firing gaseous,
    liquid, and pulverized solid fuels. The basis of the combustion facility is
    the shell of an 80-horsepawer firatube boiler which has been modified to fire
    various fuels and also includes capability of air preheat (^-600 ?) , staged
    combustion, and flue gas recirculation. The facility and burner used in
    cofiring the coal and RDF are illustrated by Figure 1.
    Testing is being conducted at a single load for all coal/RDF/vasts oil mixtures.
    The burner settings which include primary/secondary ai.r ratio and burner swirl
    are net being varied oarametrically but rather have been optimized in terms of
    flame stability for each of the RDF/coal/waste oil mixtures. The combustion
    parameters that are being investigated during the program include:
    RDF Type
    RDF/Coal/Waste Oil Ratio
    Excess Air
    Air Preheat
    Staged Combustion Configuration
    167
    :
    -------
    TEST RESULTS
    Included in this paper are the available gaseous and particulate results which
    have been performed to date. Samples are currently undergoing analysis for
    trace elements and organics and no results are presently available. The
    results which will be discussed were obtained burning the CZA material cofired
    with coal.
    The gaseous data which were obtained are nitric oxides (NO), carbon monoxide
    (CO), carbon dioxide (CO2), excess oxygen (02), unburned hydrocarbons (UHC),
    sulfur dioxide (SO2) , chlorine (CI), fluorine (F), and bromine (Br). The
    CI, F, and 3r were obtained only on certain test points, with all other data
    obtained for each test point.
    The gaseous emissions from the cofired coal and RDF are given in Figures 2, 3,
    and 4. The NO emissions for single-stage combustion are shown in Figure 2; the
    SO2 emissions are shown in Figure 3. It can be seen from these data that the
    NO and SO2 emissions increase as the percentage of RDF is increased to
    20 percent; emissions then decrease as the RDF fraction is increased to
    50 percent. Based upon the RDF fuel analysis supplied by the manufacturer and
    an independent testing lab analysis for the coal as given in Table 1, both the
    NO and SO2 emissions should decrease as the RDF material is cofired with the
    coal due to the lower nitrogen and sulfur content of the RDF.
    The unburned hydrocarbon emissions for the cofiring points were essentially
    0 ppm. The carbon monoxide amissions were lower with increasing percentages
    of RDF than for coal alone, as illustrated by Figure 4. Typically, the emis-
    sions were about 50 ppm lower at a ratio of 50 percent RDF and 50 percent coal.
    The chlorine, fluorine, and bromine concentrations are shown in Table 2 for
    all tests completed to date. Also included in this table are the particulate
    loadings and 30^ concentration.
    The loading results are consistent with what would be expected based on the
    percentage of ash contained in the coal and the RDF, since there is less than
    a percentage point difference in those ash values. The SO3 values for the
    baseline coal are consistent with previous measurements that show a decrease
    in SO3 concentration wirh staged combustion. However, this trend was reversed
    when 50 percent RDF was fired. Additional measurements are necessary before
    any conclusions can be made on the significance of this result.
    The halogens show increased concentrations over the base coal when RDF is
    cofired. The multiple values for Test No. D reflect that two separate samples
    were taken at different times during the test and each analyzed. This probably
    reflects the compositionality of the RDF. Also, the data shows a trend of
    increasing halogen emissions as the percentage of RDF in the fuel is increased.
    Again, additional tests are required before firm conclusions can be drawn from
    these data.
    163
    KVB12-P-241
    

    -------
    ADDITIONAL TESTING
    Further casting is planned to characterize the amissions from the cofiring
    ox the Americolocy 3DF and coal. Also planned for inclusion with these tests
    is the burning of transformer waste oil in combination with coal and RDF and
    with the coal only. Results are anticipated by November of this year.
    169
    KV312-9-241
    

    -------
    o
    to
    I
    I
    ro
    1. LiMI ' f*-' '*¦ _
    
    III
    
    0
    u»r c«m
    -------
    900
    300
    700
    600 —
    >
    a
    500
    m
    O 400
    Z
    300
    200 —
    % 3DF
    10%
    O 1
    ~ 20%
    O 50%
    ot
    10
    12
    EXCESS 02 PERCENT
    Figure 2. Nitric Oxide Emissions Cafired Coal and
    CEA SDF single Stage Combustion.
    171
    KV312-P-241
    

    -------
    TABLE 1
    ULTIMATE FUEL ANALYSIS
    Chemical Analysis
    (Dry Basis)	CEA RDF	Coal
    Carbon 39.32	74.17
    Hydrogen 4.82	4.98
    Nitrogen >0.1	1.34
    Chlorine 0.29	0.04
    Sulfur 0.74	1.05
    Ash 9.71	9.33
    Oxygen (Diff) 44.62	9.09
    100.00	100.00
    HHV, Btu/lb (dry basis) 7,754	13,206
    172
    XVB12-P-241
    

    -------
    % RDF
    EV
    T
    0	2	4	5	8	10
    EXCESS 0, psacsiT
    Figure 3. Sulfur Dioxide Emissions Cofirsd Coal and RDF.
    173
    ¦CV312-P-2 41
    

    -------
    360
    320 _
    5.5% 0^ Single Stage
    Q 6% 0^ Single Stage
    P"*| 4% 02 Single Stage
    280 _
    240 —
    2- 200
    u
    Q
    w
    X
    O
    z
    160
    z
    o
    a
    OS
    
    -------
    TJVBLE 2
    Test No.
    Excess
    Oxygen
    Particulate
    Load tng
    EO^
    CIj
    BR
    F
    Fuel
    Type
    Type
    Firing
    Condition
    
    Percent
    lb/106 Utu
    ppm
    ppm
    ppra
    ppm
    
    
    A
    5.4
    2.29
    3.04
    14.2
    0.09
    3.0
    Coal
    Single Stage Coinb.
    B
    5.35
    3.55
    0
    13.5
    0.00
    2.4
    Coal
    Two Stage Comb.
    C
    5.7
    3.17
    H/A
    53.2
    0.6
    2.3
    10* CEA RDF/
    90* Coal
    Single Stage Coin)).
    D
    6.5
    3.4B
    N/A
    79.4
    0.6
    2.6
    20% CEA RDF/
    80% Coal
    Single Stage Conib.
    &
    6
    2.17
    0
    55.G2
    0.15
    14.0
    50% CEA RDF/
    50% Coal
    Single Stage Couib.
    F
    5.0
    2.28
    4.4Q
    79.4/
    146.1
    0.21/
    0.07
    5.71/
    11.6
    50% CEA RDF/
    50% Coal
    Two Stage Comb.
    i
    •u
    to
    I-4
    

    -------
    PILOT SCALE EVALUATION
    OF FOUR REFUSE-DERIVED FUELS
    R. A. Brown
    Acurex Corporation
    485 Clyde Avenue
    Mountain View, California
    176
    

    -------
    Abstract
    Pilot Scale Evaluation of Four Refuse-Derived Fuels
    R. A. Brown
    The EPA is continuing to explore control technology in the
    areas of alternate fuels, waste fuels and control of NOx emissions
    for boilers in the government-owned test facility located at Acursx
    Corporation.
    Baseline tests on refuse derived fuels (HDF) fired either
    with pulverized coal or natural gas were determined. Emissions
    assessments made include NOx, CO, particulate loading and size dis-
    tribution, twelve trace metals and a cursory search for ?C3 and
    POMs. NO^ emissions decreased as the percent ?DF increased even
    though the available fuel nitrogen increased. Particulate loadings
    from the PDF were concentrated in the less than ly size fraction.
    This project was supported by EPA Contract 53-02-1385. Mr.
    H. M. Freeman was the project officer.
    177
    

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    PILOT SCALE EVALUATION OF FOUR
    REFUSE-DERIVED FUELS
    INTRODUCTION
    There is considerable heating value (4000 to 7000 3tu/lbm)
    associated with municipal solid waste. If this resource could be
    used in steam boilers, rather than lost by incineration, a signifi-
    cant energy resource would be tapped.
    Research studies have included using heat recovery incin-
    erators, spreader type stokers and suspension firing in large elec-
    tric utility boilers. The EPA has supported experiments in cofiring
    the refuse-derived fuel (RDF) in full scale boilers in St. Louis,
    Missouri, Ames, Iowa, and Columbus, Ohio (References 1 through 4).
    Although these full scale experiments are providing useful
    data, problems associated with the many varieties of RDF need to be
    studied. Because the refuse comes from local municipalities, there
    can be significant variations in the combustion and environmental
    characteristics of the fuel from season to season or from locale to
    locale.
    There is little published data on the emissions from RDF when
    cofired with other fuels. Kilgroe (Reference 5) reported that the
    St. Louis demonstration site produced a moderate increase in chloride
    emissions but that the RDF did not significantly affect the S02 or
    NO emissions. Little information is available on the amount of
    x
    trace metals and organics or the nature of the particulates. The
    work performed here, provides the initial data base to answer environ-
    mental questions on four RDF's.
    178
    

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    EXPERIMENTAL HARDWARE
    The EPA experimental multiburner, furnace facility (Figure 1)
    was developed to study control technology problems associated
    with large-scale and utility and industrial boilers- Details on
    this facility design have been discussed in other papers (References
    5 and 7).
    The furnace fires from 293 kW-thermal to 880 kW-thermal (1 to
    3 x 10s 3tu/hr) depending on the fuel and heat release per unit
    volume being simulated. The facility may either be front-wall
    fired using one to five variable swirl block burners, or it nay be
    comer-fired using four to eight tangentially-fired burners pat-
    terned after Combustion Engineering's design.
    The standard gaseous emissions (NO, CO, CO0^/ 30^) were
    continuously monitored throughout the test program. Particulates
    were obtained using a high volume EPA method 5 stack sampler; trace
    metals and organics sampling was obtained using the Source Assess-
    ment Sampling System (Reference 3).
    The refuse-derived fuel tests were conducted in the main
    firebox in the tancentially-fired mode. First, a feed system (Fig-
    ure 2) was designed to control and measure from 10 to 60 lbs/hr of
    varied refuse-derived materials. RDF is delivered to the upper
    part of two diagonally opposed corner-fired burners. Natural gas
    or coal is also delivered to these burners and to the other two
    burners. The RDF feed system consists of a rotating drum hopper
    which deposits the aiaterial on a conveyor belt. The conveyor de-
    livers the material to a vertical downcomer, where it is pushed
    through by a blast of air. Additional air at the junction of the
    vertical downcomer and horizontal feed tube conveys the RDF into
    the furnace through a horizontal water-cooled feed tube. The RDF
    feedrata is controlled by a variable speed drive on the feed belt;
    the drum is maintained at constant optimum speed to keep the feed
    belt full.
    179
    

    -------
    The delivery tube is sized to prevent blockage while mini-
    mizing the transport air. This sizing is critical for a small-scale
    facility where the minimum pipe size is governed by the maximum
    particle size and the minimum conveyance air needed to keep the ma-
    terial suspended. The received RDF material was shredded from a
    nominal 2 to 4 inches down to 1 to 2 inches using a conventional
    garden shredder to reduce the feed tube diameter and transport
    air flow to an acceptable level.
    EXPERIMENTAL RESULTS
    The test program determined the gaseous, particulate trace
    metal and organic emissions of refuse-derived fuel from San Diego,
    California; Richmond, California; the Americology Facility in
    Milwaukee, Wisconsin; and Ames, Iowa.
    All of these materials had gone through metals and glass
    separation and a primary shredding. Table I shows the composition
    and heating value for each fuel type.
    Figure 3 shows the effect of NO versus excess air for the
    four fuels at 20 percent RDF and 80 percent natural gas. Although
    the NO levels are not particularly high, there was a definite dif-
    ference between the fuels. The NO also increases with both excess
    air and increases in RDF. Also, when the percent RDF is increased
    and cofired with coal, the NO levels decrease (Figure 4) while total
    fuel nitrogen increases. This is possibly the result of enriched
    fuel jets at the coal-refuse injection guns. Except at very low
    excess air (5 percent) CO levels were always less than 100 ppm.
    Results from the particulate, trace metal, and organics
    sampling also provide some interesting preliminary information on
    RDF emissions. Table II shows the results of particulate concen-
    trations in the various size cuts for four RDF materials cofired
    with natural gas. Although the total particulate quantity was
    quite low in all cases, the majority of particles were smaller than
    180
    

    -------
    ly and coll acted only on the filter. Although the particulate may-
    be rather friable and break up in the sampling equipment during
    collection, it may eventually end up in the respirable size range.
    Table III shows particulate loading in the same size cuts for
    two levels of Richmond RDF cofired with coal and for coal alone.
    With the substitution of RDF, the total grain loadings decreased
    with increasing RDF. However, in both cases, adding RDF increased
    the percent of material in the lu size cut over coal alone. Thus,
    it appears that adding RDF may increase the grain loading in size
    cuts less than lu. This result could produce problems for flyash
    collection equipment. Percent combustibles in the particulate
    were generally Less than 2 percent except when the excess air
    levels were 10 percent or less. This result also corresponds to
    generally low CO (<100 ppm) and unbumea hydrocarbon levels.
    Table TV lists the total trace metals in microcrams/3Cu
    found in the particulates and the condensible vapor for: (1) coal
    only, (2) coal plus 10 percent RDF, and (3) gas plus 10 percent RDF.
    Increases in trace metal concentrations varied among the three
    tests. In the coal only test, the lead concentration was exception-
    ally high. In addition, no correlation was found as the percent
    of RDF was increased.
    It is difficult to draw any conclusions from this trace
    metal data. Several factors may be contributing to the data vari-
    ability:
    •	The RDF material is nonhomogeneous and will vary from
    minute to minute, hour to hour, and season to season
    •	Metals from the furnace and sampling system could con-
    tribute to the trace metal loadings
    •	Hold up in the convective section
    •	Analvtical error
    181
    

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    These factors indicate the need for a broader data base to
    draw meaningful conclusions on trace metal concentration when co-
    firing RDF with other fuels. This data will contribute to that
    base, but a larger sample of data is needed to statistically de-
    termine real trace metal effects.
    In addition to trace metals, a limited search for organics
    in terms of (PNA or PC3's) was undertaken. A portion of the par-
    ticulate and the XAD-2 organic section resin of the SASS train were
    analyzed by liquid chromatography according to EPA Level 1 procedures
    (Reference 9). Of the material divided into the standard seven
    cuts, only cuts two and three were expected to contain PNA and
    PC3. Therefore, these two fractions were combined for a single
    GC/MS analysis. Five out of nine tests where organic samples were
    taken contained no detectable compounds. Test conditions, and the
    PNA found in the remaining samples, are listed in Table V. Mo PCB
    was found in any of the test samples.
    Little organic material, combustible CO, and unburned hydro-
    carbons were found in the particulate and gaseous streams. It has
    been reported (Reference 5) that significant quantities of unburned
    material have been found in full-scale tests. These pilot scale
    tests have higher combustion efficiency over full-scale tests pos-
    sibly because of the additional shredding and/or hot refractory
    walls providing an improved ignition source.
    In summary, up to 30 percent RDF may be cofired in a subscale
    test facility without experiencing a reduction in combustion effi-
    ciency. Additional studies are necessary to determine how this
    technology can be implemented in a full-scale facility using the
    same degree of efficiency but a higher RDF percentage. Furthermore,
    the flame's heat transfer characteristics must be clearly defined
    to determine the effect on the boiler steamside or to design a
    boiler specifically for cofiring RDF. Finally, more data is needed
    to statistically determine the trace metal and organic makeup of
    RDF cofired boilers emissions.
    182
    

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    |EE/S 002c|
    Fiyure 1. Photograph of experimental multiburner furnace.
    

    -------
    Feed System
    Tangential Burner
    Main Firebox
    Figure 2. RDF feed system and firebox.
    184
    

    -------
    20% Refuse/Natural Gas
    0 Ames
    g Richmond
    & Americoiogy
    lQ San Diego
    % Ndmmf
    200
    .946
    o
    £ 100
    10 20
    30
    0
    EA%
    Figure 3. Saseline i:Ox — amissions - HEP and gas.
    185
    

    -------
    Richmond Reiuse/Pittsburg Coal
    600
    500
    400
    a 300
    200
    100
    30
    20
    40
    10
    0
    % RDF (Heat Input)
    Figure 4. Effect of percent RDF coal and RDF.
    186
    

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    TABLE I. RDF FUEL ANALYSES
    Ultimate Analysis*
    Fuel Type
    Pittsburg
    No. 8 Coal
    Klclnnond
    Kefuae
    Ames
    Kefuse
    Aiuerlcology
    Refuse
    San Diego
    Refuse
    Carbon X
    75.23
    42.60
    40.49
    40.29
    38.01
    Hydrogen X
    5.15
    6.26
    6.01
    5.88
    5.64
    Oxygen X
    8.12
    37.90
    30.04
    25.20
    17.40
    Nitrogen X
    1.49
    0.83
    0.73
    0.91
    0.69
    Sulfur X
    2.51
    0.16
    0.35
    0.17
    0.21
    At.lv X
    7.50
    12.25
    22.38
    27.55
    38.05
    Moisture X
    
    
    
    
    
    (oa received)
    0.93
    23.8
    15.2
    24.4
    26.3
    Chlorine X
    0.14
    .46
    .43
    .72
    .79
    Heating Value
    
    
    
    
    
    Utu/lb
    13,545
    7696
    7831
    7164
    7146
    A
    Dry Baals
    

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    TABLE II. EFFECT OF RDF TYPE ON PARTICULATE SIZE DISTRIBUTION
    
    Filter
    > 10 M
    > 3 |i
    >1M
    Fuel
    Qcy (gr/fc3)
    X
    Qty (gr/fL3)
    X
    Qcy (gr/ft3)
    X
    Qty (gr/ft3)
    X
    20X Ames
    0.039
    0.011
    0.003
    0.004
    + NaC Cas
    (69)
    (19)
    (6)
    (6)
    20% Richmond
    0.032
    0.0004
    0.0004
    0.0024
    + NaC Cas
    (91)
    (1.)
    (I)
    (7)
    20% Ainerico-
    logy
    + Nat Gas
    0.041
    (86)
    0.002
    (5)
    0.002
    (5)
    0.002
    (5)
    20% San Diego
    0.062
    0.007
    0.002
    0.006
    +- Nat Gas
    (80)
    (9)
    (3)
    (8)
    

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    TABLE III. EFFECT OF COAL AND RDF CONCENTRATIONS ON PARTICUI.ATE SIZE DISTRIBUTION
    Fuel
    Filter
    >10ti
    >3li
    >lM
    Qty (gr/fi3)
    X
    qty (gr/ft3)
    X
    Qty (gr/ft3)
    Z
    Qty (gr/ft3)
    X
    202 Richmond
    RDF
    + Co.il
    .026
    (9.1)
    .134
    (47.3)
    .107
    (38.0)
    .016
    (5.5)
    102 Kicliinonil
    RDF
    ^ Coal
    .0 44
    (7-6)
    .269
    (46.1)
    .226
    (38.8)
    .044
    (7.6)
    Coal Only
    .021
    (2.1)
    .539
    (56.3)
    .344
    (35.9)
    .055
    (5.7)
    

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    TABLE IV. TRACE MliTAL CONCENTRATION FOR COAL VS 10% RDF + COAL VS 10% RDF + GAS (jig/Btu)
    ELEMENT
    Coal Only
    10Z RDF + Coal
    10% RDF + Gas
    
    TeaC 040
    Test 038a
    Test tfllba
    Cm
    L. 9581
    <0.3319
    0.3402
    Zn
    0.5294
    0.8227
    0.4468
    Mn
    0.1526
    <0.2693
    0.0209
    Pb
    17.5319
    0.3091
    1.4996
    Cd
    o;oo9i
    0.004 8
    0.0062
    lie
    <0.0176
    0.0013
    <0.0034
    T1
    <1.7540
    <0.0587
    <0.0277
    Sb
    <0.0020
    <0.0090
    0.0333
    Sn
    0.1300
    <0.0913
    <3.5033
    "b
    <0.0015
    <0.0173
    <0.0009
    As
    <0.0881
    <0.0323
    <0.0184
    d207. excess air
    

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    TABLE V. 0RGA21ICS FOUND
    Test Condition
    Organic
    Amount (ug/104 Btu)
    Gas Coflre
    Fluoranthene
    10
    10% RDF
    Pyrene
    332
    20% EA
    
    
    Ames Fuel
    
    
    Gas Coflre
    Phenanthrene
    64
    10% RDF
    Fluoroanthene
    160
    20% EA
    Pyrene
    576
    Richmond Fuel
    Dlphenyi Elher
    3395
    
    Blphenyi Phenyiether
    1697
    Gas Coflre,
    Phenanthrene
    59
    10% HO*
    Pyrene
    104
    2C% EA
    
    
    M.Tiericology F-.el
    
    
    Coal Coflre
    Ptienanthrene
    98
    10% RDF
    
    
    20% EA
    
    
    191
    

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    REFERENCES
    1.	Vaughan, D. A. and Associates. Report of First Year Research
    on Environmental Effects of Utilizing Solid Waste as a Supple-
    mentary Powerplant Fuel, Battelle Columbus Ohio Laboratories,
    EPA Research Grant R-304008, June 1975.
    2.	Nydick, S. E. and Hurley," J. R. Study Program to Investigate
    Use of Solid Waste as a Supplementary Fuel in Industrial Boilers,
    Thermo-Electron Corporation. EPA Contract Mo. 63-03-3005,
    January 1976.
    3.	Riley, B. T. Reliminary Assessment of the Feasibility of
    Utilizing Densified Refuse Derived fuel (DRDF) as a Supplementary
    Fuel for Stoker Fired Boilers, published report to EPA, 1975.
    4.	Vaughan, D. A., Krause, H. H., Hunt, J. Cover, ?. W.,
    Dickson, J. 0., and Boyd, w. K. Environmental Effects of Utili-
    zing Solid Waste as a Supplementary Powerplant Fuel. Seventh
    Quarterly Progress Report, EPA Research Grant 304008-02-1, 1975.
    5.	Kilgroe, J. D., Shannon, L. J., Gorman, P. Environmental Studies
    on the St. Louis Union Electric Refuse Firing Demonstration.
    6.	Brown, R. A., et al. Pilot Scale Investigation of Combustion
    Modification Techniques for N0X Control in Industrial and Utility
    Boilers. iPA-600/2-76-152b. Proceedings of the Stationary
    Source Combustion Symposium, Volume II, June 1976.
    7.	Brown, R. A., et al. Investigation of Staging Parameters for
    NOx Control in Both Wall and Tengentially Coal-Fired Boilers.
    EPA-600/7-77-073C. Proceedings of the Secondary Stationary
    Source Combustion Symposium, Volume III, Stationary Engine,
    Industrial Process Combustion Systems, and Advanced Processes,
    July 1977.
    8.	Blake, D. Source Assessment System Design and Development, EPA-
    600/7-78-01S, August 1977.
    9.	IERL/RTP Procedures Manual: Level 1, Environmental Assessment,
    Second Edition. June 1976.
    192
    

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    APPLICATION OF SLIPSTREAMED AIR POLLUTION
    CONTROL DEVICES ON WASTE-AS-rUEL PROCESSES
    Fred D. Hall, John M. Bruck, and Diane N. Albrinck
    PEDCo Environmental, Inc.
    Robert A. Olexsey
    U.S. Environmental Protection Agency
    INTRODUCTION
    PEDCo is currently involved in an EPA contract for testing
    and evaluating prototype air pollution control devices on various
    waste-as-fuel processes for the control of potential harmful air
    emissions. As part of the contract, sampling and analysis pro-
    grams were conducted at the RDF and coal cofiring facility in
    Ames, Iowa and the mass burn incineration facility in Braintree,
    Massachusetts. These programs involved evaluating the pollutant
    removal efficiency of a pilot fabric filter, a pilot scrubber,
    and a pilot ESP. The objective of the program was to determine
    pollutant removal efficiencies of each device for variable proc-
    ess and control device operating parameters. Operation ana
    testing of the control devices took place in October and November
    1978 and June through October, 1979.
    This project focused on three primary thermal waste-as-
    fuel technologies: 1) Co-firing - The combined firing of a
    solid, largely cellulosic waste with coal, oil, or natural gas in
    a modified conventional boiler, 2) Mass burn incineration - The
    combustion of unprocessed or processed solid wastes in water-
    wall incinerators for the generation of steam, ana 3) Pyrolysis -
    The thermochemical decomposition of solid wastes in an oxygen-
    starved environment that converts a heterogeneous waste material
    into a liquid, gaseous, or solid fuel product.
    These technologies were studied with respect to atmospheric
    pollution and potential control techniques in various phases as
    follows: 1) Collection of data on known and potential air pollu-
    tants for waste-as-fuel processes, 2) Assessment of air pollution
    control devices applicable to waste-as-fuel processes, 3) Deter-
    mination of the best air pollution control devices to be de-
    veloped as pilot-scale air pollution control devices for the most
    194
    

    -------
    significant problems associated with waste-as-fuel processes, 4)
    Procurement of two to four pilot-scale air pollution control
    devices, and 5) Operation of the pilot-scale units to generate
    and analyze data-
    Midwest Research Institute (MRI), concurrent with the PEDCo
    effort, conducted a comprehensive environmental assessment of
    various resource recovery operations for EPA. Data from this
    project provided valuable technical information for the PEDCo
    study with respect to test site and control device selection, and
    air pollution problems associated with waste-as-fuel processes.
    PRELIMINARY PROGRAM
    The nature and magnitude of atmospheric pollutant emissions
    from waste-as-fuel processes were investigated as were the
    requirements for emission control technology. The focal point of
    the study was the combustion process. Pyrolysis processes are
    still under development and no continuously operating systems
    were available for testing. Therefore, pyrolysis was not of
    primary interest in this project.
    Waste preparation (preprocessing) as well as the combustion
    process were studied. Particulate was the most apparent problem
    associated with waste preprocessing but for the combustion proc-
    ess, trace elements in the particulate as well as gaseous chlo-
    rides and mercury vapor were also cf interest. Previous studies
    had theorized that there logically should be an increase in
    particulate emissions when co-firinc RDF and coal versus coal-
    firing alone because of the normally greater ash content of RDF
    versus coal and an expected decrease in control device efficiency.
    Although the MRI study did not show a definite increase in par-
    ticulate emissions for co-fired boilers, gaseous chlorides as
    well as trace elements in the particulates such as lead, copper,
    and zinc were shown to increase when burning RDF plus coal versus
    coal alone while others, such as iron and calcium were shown to
    decrease.
    From an air pollution control technology standpoint, PEDCo
    investigated state-of-the-art technologies (e.g., fabric filter,
    ESP, and scrubber) for control of waste-as-fuel processes as well
    as more novel devices (e.g., wet ESP's, jet ejector scrubbers,
    etc.). Fabric filters have been successfully applied to prepro-
    cessing operations and ESP's are the most common air pollution
    control equipment used cn co-fired boilers and mass burn incin-
    erators. Full scale fabric filters have not been applied to
    waste-as-fuel combustion processes and wet scrubbers have been
    195
    

    -------
    used on incinerators with less success. Since state-of-the-art
    devices effectively controlled pollutants of concern from waste-
    as- fuel processes, the other more novel devices were not considered
    for the PEDCo test program.
    TEST PROGRAM
    Early in the project, several waste-as-fuel facilities were
    visited as a prelude to later, more extensive test site selection
    and to observe the effectiveness of the applied control technolo-
    gies. Table 1 describes those sites visited.
    TABLE 1. PEDCo RESOURCE RECOVERY SITE VISIT SUMMARY
    Generic
    technology
    Plant
    location
    Preprocessing
    product
    Preprocessing
    Missions
    control
    ROF
    combustion
    equlonent
    Casbustlon
    enlssion
    control device
    Co-Mr1ng
    Ants. Iowa
    Chicago SW
    Colimbus. Ohio
    Hagentowi, MO.
    Milwaukee. Wis.
    Fluff
    Fluff
    Shredded wste
    ?ellets
    Fluff
    Saghouse system
    Saghouse system
    None
    •lore
    lagftouse systen
    Pulverized coal and
    stoker-bol ler
    Pulverized coal
    boiler
    Stoker-boiler
    Stoker-boiler
    Pulverized coal
    boiler
    ESP
    ESP
    Cyclone
    Cyclone
    ESP
    Mass burn
    Chicago. Ntl
    Harrliburg, P».
    Nashville, Tenn.
    Saugus. Mass.
    Hamilton, Ontario
    Jraintree, Mass.
    Bulky Itens
    removed
    Sulky iten
    rwoved
    Sulky Items
    removed
    As received refuse
    Pulverized refuse
    As received refuse
    .lot Applicable
    Hot applicable
    Not applicable
    Not applicable
    None
    Not applicable
    Incinerator/boiler
    Inc1nerator/bo1ler
    Incinerator/boiler
    Inclnerstor/boi1er
    Inclnerator/boller
    Incinerator/boiler
    ESP
    ESP
    ESP
    ESP
    ESP
    ESP
    Pyrolysls
    South Charleston,
    W. Va.
    Shredded waste
    None
    Open burner
    None
    Other
    Fairmont, M1nn.
    Houston, Texas
    Minneapolis, Minn.
    Shredded waste
    Shredded waste
    Oevatered sludge
    None
    Bagnouse
    None
    Inc1nerator/bo1ler
    Cement kiln (co-
    fired with gas)
    Multl-hearth sludge
    Incinerator
    Wet scrubber
    Wet scrubber
    None
    From these sites, the Ames, Iowa cofiring facility and the
    Braintree, Massachusetts incinerator were selected as test sites
    because of the cooperation of the management, availability of
    data from the MRI source assessment project, high reliability of
    the preprocessing and utility operations, and limited facility
    modifications required.
    196
    

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    The execution of a program of this type relies heavily on
    the cooperation of plant management. The administrative, oper-
    ating, and maintenance staffs of the Ames Municipal Electric
    System and the Braintree Municipal Incinerator provided EPA and
    PEDCo with invaluable assistance throughout the program.
    ' Concurrent to the site selection process, available pilot
    air pollution control devices were investigated. Suitable pilot
    ESP's and scrubbers were available from vendors and IZRL/RTP. A
    transportable pilot fabric filter typical of a full scale unit
    was not available for the test program. Since the fabric filter
    testing was to be an integral part of the test program, a 1.4 nvVs
    (3000 acfm) pilot fabric filter was designed and assembled by
    PEDCo for IERL/Cincinnati.
    The project objective for both test sites was to character-
    ize the specific pollutant removal efficiencies of each control
    device for. different boiler loads, RDF inputs, and operating
    parameters. It has been assumed that any full-scale application
    of these control devices to a coal- and RDF-fired boiler must
    operate with varying flue gas temperatures and compositions. A
    plan was developed to monitor and measure these two factors, but
    not co modify or control them.
    The IZRL/RTP mobile ESP and scrubber as well as the IZRL/Cin-
    cinnati pilot fabric filter were slipstreamed on Ames' 3oiler 7.
    The scrubber and ESP were tested in October and November 1973
    while the fabric filter was tested in June and July 1979. Ames
    Boiler 7 is a tangential fired pulverized coal unit with a 33 MW
    capacity. During the test program, RDF supplied from 0 to 25
    percent of the total boiler heat'input. The scrubber was tested
    both upstream and downstream (primary and secondary) of the exist-
    ing full seals ESP and the mobile ESP and fabric filter were
    tested only as primary devices.
    At Ames, total uncontrolled particulate emissions did not
    appear significantly different when comparing coal only tests to
    coal plus RDF tests. Some uncontroleed trace elements and
    gasecus chlorides increased significantly when burning RDF plus
    coal. Lead and zinc amissions concentrations were about 3 times
    higher and gaseous chlorides emission concentrations were about
    ten times higher when burning 2 5 percent RDF plus coal than when
    burning coal alone.
    The scrubber operated at pressure drops of 25.4 and 76.2 cm
    (10 and 30 in.) H2O. The particulate removal efficiency of the
    scrubber was consistently above 9 9 percent when used as a primary
    device but considerably less (72 to 97 percent) when used as a
    secondary device. The particulate removal efficiency of the ESP
    ranged from 94 to 98 percent ana cf the fabric filter above 99
    197
    

    -------
    percent. Neither scrubber, ESP, or fabric filter particulate
    removal efficiencies changed appreciably as the portion of heat
    input supplied by RDF increased. The efficiency of trace element
    removal was typically less with the scrubber than with the ES? or
    fabric filter. For example, lead removal efficiency was about 90
    percent with the scrubber, but greater than 95 percent with the
    ESP and fabric filter. Alternatively, the gaseous chloride
    removal efficiency was greater than 95 percent for the scrubber
    but negligible for the ESP and about 20 percent for the fabric
    filter.
    At Ames, the full scale fabric filter controlling the pre-
    processing. system was tested to determine its particulate removal
    efficiency. The fabric filter controlling the 140 Mg (150 tons)
    per eight hour day plant operates at 22.4 m^/s (47,000 acfm) and
    collects the in-plant air via hoods located at critical dusting
    points, 'especially transfer points. The cleaned air from the
    fabric filter is discharged back into the resource recovery
    plant. The tests showed average inlet and outlet concentrations
    of 44 6 mg/m3 and 9.7 3 mg/m^ respectively for an average particu-
    late removal efficiency, of 97.8 percent.
    The IERL/Cincinnati pilot fabric filter and a pilot venturi
    scrubber from Neptune/Airpol were slipstreamed as primary con-
    trols on the Braintree Municipal Incinerator. These control
    units were tested August through September 197 9. The Braintree
    plant has two waterwall incinerators with a design capacity of 5
    tons of unprocessed refuse per hour each. Incinerator No. 1
    which operates continuously was used for testing, and it is
    controlled by a Wheelabrator-Frye ESP.
    The pilot fabric filter that was tested at the Ames site was
    transported to Braintree and slipstreamed upstream of the full
    scale ESP. The fabric filter was automatically operated and
    functioned 24 hours a day. By varying operating conditions of
    the fabric filter and maintaining steady-state conditions at the
    furnace and boiler, the control performance of the fabric filter
    was evaluated with respect to: precoating, pressure drop, air-
    to-cloth ratio, and cleaning mechanism. A lime precoat was added
    to the flue gas stream during some of the tests upstream of the
    fabric filter but downstream of the inlet sampling location. The
    pressure drop across the fabric filter ranged from 3.9 to 15.8 cm
    (3.5 to 6.2 in.) of water. The cleaning mechanism was reverse
    air, shake, or both. Varying the air-to-cloth ratio from 1.1 to
    2.0 did not significantly effect the pollutant removal efficien-
    cies. The cleaning mechanism also did not appear to have a
    perceptible affect on performance, however the amount of time
    necessary for each mechanism varied. Shaking took the longest,
    reverse air next and both took the least amount of off-line
    cleaning time. The particulate removal efficiency averaged 95.2
    percent for all tests. Most trace element removal efficiencies
    198
    

    -------
    were consistent with the particulate removal. Sulfur oxides were
    not effectively controlled by this device, however precoating the
    fabric with lime roughly doubled the SOx removal efficiency (20
    to 40%), when compared to the "without precoating" tests. Gas-
    eous chloride removal efficiency for "without precoating" tests
    a\feraged 23 percent, and increased to 38 percent with the lime
    precoat.
    The scrubber used at this site was a pilot venturi scrubber
    rented from Neptune/Airpol. It was installed on Braintree's
    incinerator no. 1, using the same slipstream duct work as the
    pilot fabric filter. The pilot scrubber operated unfiltered,
    recirculating scrubber liquor. The pH was controlled through
    addition of soda_ash. The liquid-to-gas ratio ranged from 5.5 to
    18.4 gal/1000 ft and the pressure drop ranged from 10 to 32 in.
    H2O. The particulate and trace metal removal efficiencies for
    the scrubber were much lower than the pilot fabric filter, how-
    ever, gaseous chlorides were removed with 96.5 percent efficiency.
    The scrubber tests showed some re-entrainment of particulate
    in a few'of the runs due to poor demister removal of water
    droplets. The particulate removal efficiency averaged 72 percent
    during tests in which re-entrainment was minimized.
    In summary, the fabric filter performed more effectively
    than the scrubber in removing particulate pollutants but not
    gaseous compounds.
    Currently, ail field and analytical work is completed on
    this project. One report entitled "Evaluation of Fabric Filter
    Performance at Ames Solid Waste Recovery System" is in preliminary
    draft stage and evaluates the particulate control achieved by the
    fabric filter at the Ames RDF plant. Two other reports are
    presently being prepared, one covering the evaluation of the
    mobile ESP, scrubber and fabric filter tests conducted at the
    Ames Power Plant, and the other report will discuss results of
    our tests of the mobile fabric filter and scrubber at the Brain-
    tree mass burn incinerator.
    199
    

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    TREATMENT OF WASTEWATERS "ROM
    REFUSE-TO-ENERGY SYSTEMS
    3Y
    GORDON P. TREWEEX, Ph.D.
    MEMBER ASCE
    ABSTRACT
    This paper discusses the wastewater treatment technologies that can be
    effectively utilized at WAF facilities to treat waterborae pollutants. The
    principal water-borne emissions contain organic surrogates (BOD, COD, TSS)
    in concentrations up to 100,000 mg/1 at pyrolysis units; organic priority
    pollutants in concentrations up to 100 mg/1 at pyrolysis and digester units;
    and trace metals in concentrations up to 1,000 mg/1 in incinerator scrubbers.
    The efficacy of aerobic, anaerobic, and physical chemical treatment steps
    on the wastestreams produced at incinerators, hydrapulping facilities,
    pyrolysis units, and digesters is projected and potential treatment trains
    are recommended.
    INTRODUCTION
    During the past ten years, shortages of basic raw materials such as ferrous
    metals, scrap paper, and fuel oil have prompted private and governmental
    agencies to investigate the recovery of valuable materials from solid wasres.
    James M. Montgomery, Consulting Engineers, Inc.
    S55 East Walnut Street, Pasadena, California 91101
    200
    

    -------
    For example, the fuel shortage of late 1973 and the subsequent drastic
    increase in fuel prices have resulted in a major effort to find alternative
    sources of energy. One possible source of energy is the solid waste
    generated from municipal, agricultural, and forestry operations. Although
    the composition of these wastes varies widely with the type of enterprise,
    consumer habits, geographical location, tiae of year, and numerous other
    factors, the waste streams invariably contain a high organic content which
    can be either directly combusted or converted to conventional fuels.
    Without seme fora of recovery of their material and energy properties,
    the increasing quantities of solid waste, along with projected depletion
    of economical waste disposal sites, constitute a growing waste disposal
    problem. Thus, the increased cost of fuel and raw materials coupled with
    the increased concern over the environmental impact of disposing large
    volumes of solid wastes, has prompted significant investigation into waste-
    as-fuel CWAT) processes. This paper discusses one aspect of WAT processes:
    the water pollutants produced and the technology available to treat these
    wastes.
    WASTIS7HEAM I3ENTITICATSCN
    A two-step procedure is followed in processing refuse into useable fuel:
    preprocessing and aonversion. Preprocessing consists of a series of
    physical operations which size, classify, and segregate the raw refuse
    into useable fractions. Conversion consists of cne of the follcving four
    unit operations: conbusticn (mass incineration or co-firing), pyrolysis,
    anaerobic digestion, or aethanaticn. From a water pollution control stand-
    point, filtrate frcn hydrapulping (preprocessing), incinerator scrubber
    201
    

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    washwaters, pyrolysis condensate, centrate fran anaerobic digesters, and
    leachate fran landfills (methanation) constitute the majcr sources of
    wastewater.
    The extent of water use and wastewater production axe primarily dependent
    upon the type of process utilized for preparing the municipal solid waste
    (MSW) and the actual combustion process itself. Wastewater streams range
    from very small quantities of high organic deaand wastewater, such as that
    associated with the condensate of pyrolysis units, to relatively large
    volumes of low organic demand wastewater, such as that utilized to sluice
    ash residue frca mass bum crmhustars. Four major catagories of pollutants
    were identified in the wastestrearns at WRF facilities: the organic
    surrogates (30D, COD, TSS), which measure the oxygen demand of the waste-
    water on the receiving water body; the mineral quantity, specifically
    corrosive agents such as chlorides and sulfates, and the hydrogen ion
    concentration; the organic priority pollutants including total organic carbon
    and total organic nitrogen; and the heavy metal priority pollutants. While
    in most cases, good data were available on the organic surrogates and the
    mineral quality of wastewater produced at refuse-derived-fuels (32F) and
    WAF facilities, very little inforaation was available on the organic and
    heavy metal priority pollutants.
    PTS?K0CE3SING
    The extent of wastewater production ir. preprocessing operations depends
    almost exclusively on whether wet or dry preprocessing steps are utilized.
    202
    

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    In dry preprocessing operations, vastewatars axe produced in small quantities
    at only a few locations. Water is used rarely in the actual process since
    any moisture added to the RDF oust be eventually evaporated in the conver-
    sion facility. The primary uses for water are dust control, fire fighting,
    and clean-u? activities. Water is also used occasionally in some types of
    material separation units, such as those recovering aluainum and glass.
    Wastewaters primarily originate from washdcvn operations, drainage from
    storage pits, and the above-mentioned materials recovery processes. Trash
    confined in the storage pit may leach compounds such as pesticides and
    organic solvents which can have adverse effects on wastewater treacnent,
    but these conditions must be evaluated on an individual basis and treated
    accordingly. In most cases the wastewater from dry preprocessing operations
    can be discharged safely to sanitary sewers.
    In contrast to dry preprocessing, wet preprocessing or pulping of MSV
    involves placing the material into a large hydrapulper, analogous in
    operation to a household garbage grinder. A thick slurry of MSW is formed
    with heavy particles of ferrous materials and other ncn-farrous materials
    separated by centrifugal action. The slurry containing the organic fraction,
    glass, and small pieces of metal is segregated into light and heavy fractions
    via licuid cyclone. The light organic fraction is dewatered by screening
    and pressing, and the liquid waste streaa is recirculated to the pulper.
    The dewatered pulp can be cleaned and dried for use in paper products or
    burned for energy production.
    Depending cr. the combination of energy recovery and materials separation,
    203
    

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    water is required for pulping, cleaning, equipment cooling, and resource
    recovery. In most cases the quality of water is not critical, which permits
    the use of non-potablS supplies such as sewage treataent plant effluents
    and sludges. By far the largest quantity of water is required by the hydra-
    pulper. Water far the hydrapulper can be obtained from the dewatering and
    material recovery units through recirculation.
    Three sources of wastewater exist in the hydrapulping system: the waste-
    water blowdown from the recycling hydrapulping system, the sludge/slurry
    mixture which has been dewatered in the cone press, and the effluent from
    air pollution scrubbers. These wastewaters are characterized by their
    large volume and high organic content. (Table 1.)
    CONVERSION
    Following preprocessing, the MSW is converted either directly into energy
    or into fuels for combustion. Our study found wastewaters associated
    with the two principal combustion processes; the mass burn incinerator and
    the co-firing boiler; the anaerobic digestion process; and the pyrolysis
    process. The latter two processes produce fuels for subsequent combustion.
    The wastewaters from combustion processes consist primarily of site drainage
    and washwaters; quench and sluice waters; boiler blowdown; and scrubber
    effluent. The first three categories of wastewater are generally small in
    quantity or of low strength and can be discharged directly into sanitary
    sewers. The largest quantity of water is used for scrubbing exhaust gases.
    Waterwall incinerator facilities help keep water use to a miris® by using
    204
    

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    electrostatic precipitators and dry handling systems for ash. While
    electrostatic precipitators are preferred frcm a water pollution control
    viewpoint, nevertheless wet scrubbers say be required for the removal of
    gaseous chlorides and SO2 in order to meet air quality standards. The
    scrubber waters are generally acidic, with pH's in the range 2.5 to 5.0.
    The total solids concentration varies fraa 500 to 7000 mg/1 with about
    80-85 percent being dissolved solids. The chloride, hardness, sulfate,
    and phosphate concentrations of the inccoing raw water are significantly
    increased after passing through the scrubber. Furthermore, the scrubber
    wastewaters often contain high concentrations of trace metal priority
    pollutants which must be reaoved prior to discharge to either the sanitary
    sewer or the ambient receiving water. (Table 2.)
    Pyrolysis involves heating a preprocessed to a sufficiently high tenper
    tare in a low-oxygen environment so that the organic components breax down
    chenicaliy. The heat for pyrolysis of MSw usually is obtained by totally
    oxidizing part of the refuse. The pyrolysis reacticn produces.three com-
    ponents : 1) a gas consisting primarily of hydrogen, methane, carbon mon-
    oxide, and carbon dioxide; 2) an oily or liquid fraction which contains
    organic chemicals such as acetic acid, acstone, and methanol plus water
    derived from hydrolysis or organic compounds, and 3) a solid char fraction
    consisting of unbumed carbon plus inert materials such as glass.
    Water is used in pyrolysis plants for cooling, gas scrubbing, char quenchir.
    and miscellaneous housekeeping. Wastewater straa-T.s of major concern are
    those collected from scrubbers, condensers, and ether gas cleaning devices.
    205
    

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    These wastewaters usually are high strength and contain a variety of organic
    materials formed during the pyrolytic reaction or vaporized from the raw
    RDF. A BOD5 in the range 50,000 to 100,000 ppm is caused by water-soluable
    organics such as alcohols, organic acids, and aldehydes. BOD's in this
    range are too high for conventional activated sludge and nust be pretreated
    by other processes. In addition to the high organic strength, the pyrolysis
    condensate is characterized by high concentrations of organic priority
    pollutants such as phenol, benzene, and toluene; and the gas scrubber waters
    are characterized by high concentrations of trace metal priority pollutants.
    (Table 3.)
    Anaerobic digestion of sewage sludge to produce methane gas has been a
    conanon practice in sewage treatment, however, anaerobic digestion of MSw
    is only in the developmental stage at this time. A system for digesting
    the organic part of municipal trash in a mixture with sewage sludge is
    currently under shake down testing in Pompano Beach, Florida. Two waste-
    water streams are anticipated: storage pit drainage and a liquid effluent
    generated from dewatering the digested sludge. No data are available on
    the composition of these waste streams when MSW is digested with the sewage
    sludge. We anticipate that the dewatered filtrate from the digestion of
    combined MSW/sewage sludge will be similar to that which exists at normal
    sewage sludge digesters. Thus, the wastewaters will be characterized by
    high BOD's, in the range 500-10,000 mg/1 and high concentrations of
    organic priority pollutants, in the range of 650-3,800 mg/1. (Table 4.)
    In sunmary, although many sources of wastewater exist at RDF and WAF
    206
    

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    facilities, the quantities and strengths of the wastewater are often small.
    Consequently, these wastes can usually be discharged directly into the
    sanitary sewer or held for a brief period in an -oxidation pond before
    discharge to aobient receiving waters. In addition to these snail
    insignificant scurcss, we found several major waste streans generated
    in RDF/VAF facilities. The exact quantities and strengths of these
    wastes are highly dependent upon the operating characteristics of the
    particular facility, important constraints on operating characteristics
    have been 1) the local air and water quality standards, and 2) the
    availability of sanitary sewers.
    The major waste streams of concern, associated with current 3DF/WAF
    facilities, are:
    1)	Pressate from the devatared subsystem of the hydrapulping wet
    preprocessing facility. This wastewater is characterized by moderate
    SOD/COO (less than 10,000 ag/1), moderate suspended solids (less than
    10,000 mg/1), and acidic pH (pH less than 7,0).
    2)	Pyrclysis condensates and gas scrubber effluents. These wastewaters
    are characterized by very high (greater than 10,000 mg/1) 30D/C0D, low
    (less than 1,000 mg/1) suspended solids, and high organic content,
    especially phenols and benzene caapounds.
    3)	Filtrate and supernatant from anaerobic digesters. These wastewaters
    are characterised by high (greater than 10,000 nc/1) 3GD/C0D, high
    (greater than 10,000 ag/1) suspended solids, and neutral pH's.
    4)	Gas scrubber effluent frczi combustion facilities. These wastewaters
    207
    

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    are characterized by low (less than 1,000 mg/1) 30D/C0D, low (less than
    1,000 mg/1) suspended solids, variable pH, and the presence of heavy
    metals.
    PROJECTED TREATMENT EFFICIENCIES
    The efficiencies of pollution control technologies applicable to the
    identified waste strezms are discussed in the following paragraphs.
    As presented earlier, the principal waterborae emissions are the organic
    surrogates (BOD, COD, TSS), the organic priority pollutants, and trace
    metals. The first tvo are efficiently treated with biological processes,
    either aerobic or anaerobic; whereas the latter are successfully removed
    via physical-chemical processes. Physical-chemical methods are also
    effective in removing organic surrogates but the total cost is higher
    than with usual biological processes. Similarly, some adsorption ar.d
    removal of trace metals occurs in biological processes, but this removal
    is incidental to the real purpose: the conversion of soluble organic
    material into microorganisms and gas.
    Waste streams identified as quench water, sluice water, and ash pond
    effluent associated with mass burn- and co-firing incinerators are readily
    treated with existing control technology. Other waste streams such as
    the scrubber waters at mass bum and incinerator facilities and digester
    supematants at the anaerobic digester facilities appear amenable to
    treatment via physical-chemical and aerobic biological processes,
    respectively. Which of the tvo control processes would be most successful
    in treating these wastes or whether the control processes may be required
    in tandem should be investigated in pilot studies. The remaining two
    208
    

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    waste streams, the pyrclysis gas scrubber water and the thickner waste-
    water from the hydrapulping process have far greater strength than
    normally associated with domestic wastewater. ?ilot plar.t data (14-19)
    indicate that these wastewaters should be amenable tc treatment by
    anaerobic processes; the pyrolysis gas scrubber water being especially
    adaptable to the anaerobic filter treatment process because of low
    suspended solids and elevated temperatures, the hydrapulping wastewater
    being amenable to the anaerobic biological contact process because of its
    high suspended solids. Both of these treatment processes are in the
    developmental stage and will require verification testing to determine
    operating parameters and applicability to particular waste streams.
    Aerobic biological processes can be applied effectively to any of the
    organic pollutants identified earlier. Under aerobic conditions,	the
    soluble organic matter in a waste stream is converted into active
    bicmass. Organic removal efficiencies of aerobic processes range	betveen
    80 and 90 percent. The removal efficiency of soluble organic material
    from the liquid phase is actually greater; however, enough solids	escape
    the final clarification process to reduce the overall efficiency.
    The efficiencies of the various treatment steps discussed above in removing
    significant pollutants frca pertinent industrial discharges are presented
    in Table 5. The listed industries produce wastestreams similar to those
    encountered in T0F-WJJ" facilities.
    209
    

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    KECCKMENDED PILOT PLANT STUDIES
    Based on the strengths of wastewaters produced at RDF-WAT facilities,
    and the anticipated removal efficiencies of various treatrsent processes,
    pilot plant studies are recommended to verify renoval efficiencies and to
    determine whether linkage of processes in series is required to meet
    discharge standards. The pilot plant studies would investigate the
    effectiveness of aerobic, anaerobic, and physical-chemical processes
    in obtaining the desired effluent quality.
    Two main aerobic processes are available: filters and activated sludge.
    In the biological filter, waste is applied continuously or intermittently
    to the top surface of the filter. Natural rocks or ceranic or plastic
    fill material have been successfully used as filter media. Air is
    circulated through the filter either by natural convection or forced
    draft to maintain aerobic conditions throughout the depth of the media.
    A diverse population of microbites and microlutes live on the surface
    of the media and utili2e the waste either directly or as high food chain
    consumers.
    In the activated sludge process, the microbial population is dispersed
    in the liquid phase. The population is less diverse but more concentrated
    than in a biological filter. Air is introduced into the liquid phase
    to maintain aerobic conditions and to keep the microbial population in
    suspension. Organic removal in activated sludge can be improved by
    increasing the number of microorganisms in the mixed liquor or the period
    of contact of the waste with the microorganisms.
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    In order to provide flexibility in the operation of in aerobic pilot
    plant, both the biofilter and the activated sludge processes should be
    constructed. The biological filter can be selectively inserted into
    the treatment train in front of the aeration tank. In addition to
    overall increased efficiency, the diverse biota of the biological
    filter are resistant to shock loadings and toxic elements, thus affording
    a degree of protection against npset not available in an activated
    sludge process alone. The effective depth of the biological filter can
    be varied, as can the amount of flow path of recirculation within the
    filter. Waste streams with high COD will probably require the use of a
    biological filter as a first stage roughing filter prior to activated
    sludge treataent.
    The activated sludge aeration stage should be designed as a completely
    mixed reactor; a configuration suitable for high organic loads and easy
    operation. The aeration tank should be divisible into four ccnpartaents
    to facilitate variation of aeration tiae. The aeration systea can be
    converted froa air to pure oxygen.
    Anaerobic treataent is well adapted to target waste streams containing
    high concentrations of organic surrogates. An exception to the above
    stateaer.t is the digester supernatant, where the efficacy of treating
    the effluent froa an anaerobic treataer.t systea with another anaerobic
    treataent systea is dubious.
    The efficiency of anaerobic processes appears to increase with higher
    211
    

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    concentrations of organic surrogates and high temperatures in the anaerobic
    reaction vessel. Thus, an anaerobic treatment process is ideally
    suited for a vara, concentrated waste stream. The pyrolysis waste
    is the primary candidate for anaerobic treatment because of its
    concentration and elevated temperature. Another liJcely candidate is
    the hydrapulping waste stream.
    Based on the available data for waste streams at WAT facilities, two
    anaerobic treanaent processes axe recoraended for construction in the
    anaerobic pilot plant. These processes are the anaerobic filter and
    the anaerobic contact chamber. In the anaerobic contact process, the
    solids retention tiae is increased by recirculating sludge removed in
    the secondary sedimentation tank. The anaerobic filter, on the other
    hand, retains the sludge within the primary vessel; both on the media
    and between the voids of the media. In anaerobic processes the
    conversion of soluble organics to gases is high; eighty percent gas
    (CJ4 + COj) to twenty percent sludge production is not uncommon. Because
    of this, anaerobic processes can treat large quantities of organic waste
    with only a moderate build up of sludge. Indeed, low sludge generation
    and methane production are the two major advantages ef anaerobic treatment.
    Operating experience with both types of anaerobic processes is scant.
    Our literature review showed only one full-scale operation of the anaerobic
    filter and no full scale operation of the anaerobic contact chamber. In
    spite of these limited operations, both processes have significant
    advantages over aerobic treatment. The anaerobic filter is simple to
    operate, does net require sludge recirculation, and requires construction
    of only one vessel.
    71 7
    

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    The physical-chemical treatment process is directly applicable to
    the treatment of wastes found in incinerator scrubber waters. Furthermore,
    the process aay be combined with either the aerobic or anaerobic
    treatment processes to produce an effluent acceptable for discharge
    to ambient receiving waters.
    Since a physical-chemical pilot plant nay be used in a tertiary role as
    veil as by Itself, the flow must be. ccmpatable with the other pilot
    plants, particularly with the aerobic unit. Extensive bypass capability
    oust be provided so that in the tertiary treatment mafe, individual unit
    processes can be inserted or removed as desired. The unit processes of
    flocculation, sedimentation, filtration, and carbcn adsorption should
    be provided in the physical-chemical pilot plant.
    Operational variables that can be controlled fcr experimental purposes are
    1) the chemical dose—variation in amount and type of primary coagulant and
    filter aid; 2) flocculation—flocculation energy input, detention time, and
    sludge-solid content; 3} filtration—filter media design and filtration
    rate; 4) carbon adsorption—contact time in the adsorption column.
    OnliJce the biological units, the physical-chemical pilot plant does not
    require a period of cell growth and acclamation upon startup. Most modifi-
    cations to the treatment process can be accomplished in a matter of minutes.
    Housing the physical-chemical processes in a separate trailer will provide
    additional flexibility in the sequential or concurrent operation of the
    different processes on the WAT waste streams.
    Based on the waste streams generated in W\r facilities, ar.c the available
    wastewater treatment processes and efficiencies, combinations of treatment
    213
    

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    processes nay be required to achieve the effluent limitations for discharge
    to ambient receiving waters. In most cases, the use of a single treataer.t
    process will produce an effluent acceptable for discharge to a publicly-
    owned treatment wcrXs. However, in virtually all cases, a physical-
    chemical process following either an anaerobic or aerobic process will be
    required to polish the effluent and thereby meet discharge standards for
    surface waters.
    For hydrapulping waste streams, either anaerobic or aerobic processes
    should be effective in producing a 90 percent reduction in the high BOD and
    COD of these wastewaters. Tor comparison purposes, two anaerobic processes,
    the anaerobic filter and the anaerobic contact chamber will be operated
    •v
    in parallel along with the aerobic pilot plant, consisting of a roughing
    filter and activated sludge aeration. Based on the efficiencies of these
    processes, the effluent should be acceptable for discharge to POTW. For
    discharge to surface waters, a physical-chemical pilot plant must be
    utilized to further reduce both organic and inorganic contaminants.
    (Figure 1.)
    For contaminants identified as occurring in incinerator or boiler scrubber
    waters, either aerobic or physical-chenical processes should be effective
    in treating the relatively low BOD waste streams. The physical-chemical
    pilot plant should effectively reduce both the organic contaminants ar.d the
    trace metal concentrations to levels acceptable for discharge to surface
    waters. The aerobic treatment process will probably require subsequent
    polishing via physical-chemical processes to remove trace metal contaminates
    214
    

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    to levels acceptable for discharge to surface waters.
    The waste screams produced in the condensation of cases and the
    •separation of pyrolysis fuel oils from the scrubber ail are the most
    difficult to treat. Based on the very high 300's and the low suspended
    solids iron this WAF process, the anaerobic filter appears ideally
    suited for the initial treatment step. To date, the anaerobic filter
    has been utilised only ones in full scale operations and consequently
    the pilot plant data vill be especially valuable in the development of
    this innovative technology. The anaerobic contact process will run
    concurrently with the anaerobic filter for comparison between the two
    processes. Likewise, the aerobic pilot plant should be utilized with the
    pyrolysis waste streams and the results compared with those frco the OHOX
    process utilised by the Onion Carbide Company in treating their Purox
    wastewaters. Subsequent physical-chemical treatment may be required
    prior to discharge to surface waters for the removal of traca metals
    although these have not been specifically identified in the analysis of
    pyrolysis waste streams, (Figure 3.)
    The wastewaters from the anaerobic digestion of MSW are the most poorly
    characterized because the process itself is only now undergoing full
    scale investigation. Depending on the oxygen demand of the waste streams,
    either the aerobic or the physical-chemical processes should be effective
    in its treatoient. The aerobic process would generally be ineffective
    in the removal of trace metals and consequently, based on results of
    further testing, a physical-chemical process may be required to upgrade
    the effluent. (Figure 
    -------
    In conclusion, based on the results of our investigation, we feel that
    three pilot plant trailers should be designed, constructed, and
    operated in the field at WAF facilities. These three pilot plants,
    anaerobic, aerobic and physical-chemical, should be operated both
    in series and in parallel to obtain data on the relative efficiencies
    of the different processes. The operation of the anaerobic pilot plant
    should be especially valuable because of the innovative nature cf the
    processes involved. In addition, the operation of the other pilot plants
    will provide valuable information on their respective removal efficiencies
    with respect to organic and trace metal priority pollutants. The
    successful operation of the pilot plants at WAF facilities will provide
    valuable information on the wastewater streams generated and the
    applicability of various treatment schemes in reducing the pollutant levels
    in these waste streams to acceptable levels.
    acknowledgement
    This study to characterize liquid pollutants produced at PDF-WAF facilities
    and to recc-nsnend treatment steps for their removal was funded by the
    Fuels Technology Branch, Industrial Environmental Research Laboratory,
    Environmental Protection Agency, Cincinnati, Chio.
    216
    

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    TABLZ 1
    SOMMAICf OF SIGNIFICANT POLLUTANTS IDENTITIZD IN SYT5RAPTJL?XKG KASTZ STSSAKS [i]
    ?A?jy
    -------
    TABLE 2
    SUMMARY OF SIGNIFICANT POLLUTANTS IDENTIFIED IN INCINERATOR WASTE STREAMS [2-3]
    PARAMETER (nq/13
    QUENCH WATER
    SCRUBBER WATER
    
    
    
    Organic Surrogates
    
    
    
    
    3.O.D.
    -*
    
    
    15-400
    C.O.D.
    •
    
    
    20-790
    T.S.S.
    4-4,070
    
    
    90-13,000
    Oil and Grease
    •
    
    
    •
    Mineral Quality
    
    
    
    
    +
    Na
    ca+2
    3.36-1,306
    
    
    14-1,621
    66-517
    
    
    19-1,4 99
    Total Alkalinity
    0-835
    
    
    0-2,630
    CL
    98-1,920
    
    
    180-3,540
    S042
    25-5000
    
    
    20-1,250
    ^3
    P°4
    35-100
    1-21
    
    
    10-710
    1-51 '
    CN
    •
    
    
    5.2
    pH (Units)
    3.6-11.5
    
    
    1.8-11.9
    DO
    *
    
    
    *
    Priority Pollutants
    
    
    
    
    Organics
    «
    
    
    *
    Priority Pollutants
    
    
    
    
    Metals
    *
    Hg
    AS
    
    0.03-11
    0.2-7
    
    
    T-C
    ft
    1-200
    
    
    Cr
    
    0.06-7
    
    
    Pb
    
    13-500
    
    
    Cd
    
    1.2-20
    
    
    Fe
    
    40-3,600
    
    
    Cu
    
    1-52
    
    
    Zn
    
    30-1,050
    
    
    Mn
    
    £-65
    ' Flow (liter/sin)
    Corcinec
    flows up
    to
    2,000 1/m
    218
    

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    TABLE 3
    SXSWfUCf OF SIGNIFICANT POLLUTANTS IDOTI7IZD H7 PYHOLYSIS WASTE STREAMS [9-11]
    PA2A>ETSH (bc/IJ
    PY5CLYSIS COTOEMSATE and GAS SCH033ES WATE3
    Organic Surrogates
    
    B. 0. D.
    50,000-77,000
    C.O.D.
    30,000-52,000
    T.S.S.
    30-112
    Oil and Grease
    500-1,000
    Mineral Quality
    
    Na+
    89-170+
    Ca+2
    34-135+
    Total Alkalinity
    
    CL~
    360-€90+
    S0I2
    44-€2+
    N°3
    «
    TO43
    *
    CM
    2-a+
    pH ( units )
    3.7+
    CO
    2.4-3.7+
    Priority Pollutants
    
    Qrgaaics
    Phenol 20-50+
    2-4 Diaethyl ?hcno 0.6-5+
    Benzene 4+
    TOluene 1+
    Ethylbenaene 1+
    Naphthalene 3+
    Priority Pollutants
    
    Metals
    Lead 0.3-0.S+
    Zinc 2.3-15+
    Flow (litar/nin]
    Op to 250-reports differ
    219
    

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    TABLE 4
    SUMMARY OF SIGNIFICANT POLLUTANTS IDENTIFIED
    IN DIGESTER SUPERNATANT/FILTRATE [12-13]
    PARAMETER (mc/1)
    DIGESTER SUPERNATANT/FILTRATE
    Organic Surrogates
    
    B.O.D
    500-10,000
    C.O.D.
    1,000-30,000
    T.S.S.
    200-15,000
    Oil and Grease
    «
    Mineral Quality
    
    +
    Na
    •
    ^ +2
    Ca
    *
    Ttotal Alkalinity
    100-2,700
    CL
    •
    SC42
    *
    N°3
    «
    ?°43
    •
    cn"
    *
    pH Cur-its)
    6.4-7.2
    DO
    *
    Priority Pollutants
    
    Organics
    TOtal .volatile solids 650-3,300
    Priority Pollutants
    
    Metals
    *
    Flow (liter/i&in]
    •
    220
    

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    TABLE 5
    efficiency gf treats;? processes in removing significant
    POLLUTANTS FROM PERTINENT INDUSTRIAL DISCHARGES (20-22)
    Percent Removal (\)
    Indus try/Le ve 1
    or TTeataent
    BOD
    COD
    35
    Oil i
    Grease
    Phenol
    Aitsnonia
    Sulfide
    Metals 1
    Pe trol s'ja.
    Prxnary
    3iological
    Secondary
    Filtration
    Carbon Adsorption
    Anaerobic Filter
    30-60
    40-99
    40-70
    70-98
    20-50
    30-95
    20-53
    70-94
    10-13
    50-30
    20-85
    75-95
    60-90
    60-95
    50-99
    65—95
    70-95
    0-50
    60-99
    5-20
    90-100
    0-99
    70-100
    
    Stean Electric
    Power
    Primary
    Biological
    Secondary
    Anaerobic Filter
    
    
    
    50-70
    70-90
    
    
    
    50-95 |
    Puis S Paoer
    Primary
    Biological
    Secondary
    Anaerobic Filter
    8S-99
    73-94
    95
    
    
    
    
    
    Staan Supply a
    Cooline
    Precipitation &
    Coagulation
    
    
    
    
    
    
    
    90-100 1
    Organic Cienicals
    3iological
    Secondary
    Carbon Adsorption
    93
    90
    69-74
    69
    
    
    
    
    
    
    Plastics s
    Synthetics
    Biological
    Secondary
    30-99
    90-95
    
    
    
    
    
    1
    Food Processir.c
    Anaerobic Filter
    
    55-56
    
    
    
    
    
    1
    Pharmaceutical
    Anaerobic Filter
    
    94-98
    
    
    
    
    
    1
    Wastewater Treat-
    ment Plant
    Anaerobic Filter
    85
    76
    45
    
    
    
    
    1
    i
    221
    

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    REFERENCES CITED
    1.	Ywong, J. C., and Johnson L., "Water Use and Wastewater Production
    at Solid Waste Processing/Energy Recovery Facilities," Engineering
    Research Institute, Icwa State University, Ames, Iowa, 1977.
    2.	Matusky, F. E., and Hampton, R. K., "Incinerator Wastewater,"
    Proceedings National Incinerator Conference, 1968.
    3.	Achiger, W. C., and Daniels, L. E., "An Evaluation of Seven
    Incinerators," Proceedings National Incinerator Conference, 1970.
    4.	Wilson, D. A-, and Brown, R. E. , "Characterization of Several
    Incinerator Process Waters," Proceedings National Incinerator
    Conference, 1970.
    5.	Schoenberger, R. J., et al, "Characterization and Treatment of
    Incinerator Process Waters," Proceedings National Incinerator
    Conference, 1970.
    6.	Schoenberger» R. J.» "Studies of Incinerator Operation," Proceedings
    National Incinerator Conference, 1972.
    7.	Cross, F. L., and Ross, R. W., "Effluent Water From Incinerator Flue
    Gas Scrubbers," Proceedings National Incinerator Conference, 1963.
    8.	Kaiser, E. R., and Carotti, "Municipal Incineration of Refuse with
    2 Percent and 4 Percent Additions of Form Plastics: Polyethylene,
    Polyurethane, Polystyrene, and Polyvinyl Chloride, "Proceedings
    National Incinerator Conference, 1972.
    9.	Engineering and Economic Analysis of Waste to Energy Systems, Ralph
    M. Parsons Company report to EPA Industrial Environmental Research
    Laboratory, June 1977.
    10.	Hoffman, D. A., Pyrolysis of Solid Municipal Wastes, EPA report
    67012-73-039, Cincinnati, Ohio, 1977.
    11.	Ananth, C. et al, Environmental Assessment of Waste-to-Energy Process:
    Union Carbide Purex System, MKI report to EPA Industrial Environmental
    Research Laboratory, June 1978.
    12.	Malina, J. F., and Felipo, J. D., "Treatment of Supernatants and
    Liquids Associated with Sludge Treatment," Water and Sewace wcrfcs
    Journal, August 1971.
    13.	Sludge Treatment and Disposal, EPA Technology Transfer Manual, 1974.
    14.	Jennett, J. and Dennis, D., "Anaerobic Filter Treatment of Pharmaceutical
    Waste," Journal Water Pollution Control Federation, 47,l(January 1975).
    15.	Young, J. C., and McCarty, p. L., "The Anaerobic Filter for Waste
    Treatment," Journal Water Pollution Control Federation, 41, 5 (May 1969).
    222
    

    -------
    16.	Taylor, W., Full-Scale Anaerobic Trickling Filter Evaluation, Food
    Waste Research Section, US EPA, Cincinnati, Ohio.
    17.	Sana, R. T. , Raksit, S. K. , and Wong, G. G., "Anaerobic Filter Treated
    Waste Activated Sludge" Water and Sewace Works Journal, 124, 2
    (February 1977).	'
    18.	Sanders, F. A., and Bloodgocd, D. E., "The Effects of Nitrogen-to-
    Carbon Ratio on Anaerobic Decomposition," Journal Water Pollution
    Control Federation, 37, 12 (December 196S).
    19.	Schoepfer, G. J,, and Zeiake, N. R., "Development of the Anaerobic
    Contact Process, I, Pilot Plant Investigation and Economics," Savage
    and Industrial Wastes, 31, 2 (February 1959).
    20.	State and Local Pretreataent Programs, Federal Guidelines. Volume I,
    US OA, Municipal Construction Division, Washington, D.C. January 1977.
    21.	State and Local Pretrsatment Pro
    -------
    HYORAPVUPtNfi WASTESTOCAM
    r
    ANACTOBJC
    . FILTER
    ANACRO0IC
    v 03NTACT
    SCSIMO(TAT)OH
    SCOtMeXTATION
    PR1MAPV
    tNTXRMCaAT£
    CLAfllFIER
    CFFLUCNT
    TO POTW
    EFFLuCnT
    TO POTW
    TO WTW
    n^CCJLATO*
    DUAL wEDIA |
    P1LTOTS | }
    
    1
    ' 1
    CAR30N AOSORPTIOnI |
    COLUMNS | j
    	
    ^1
    PHYSIOL
    CHEMICAL
    PILOT
    PLANT
    effluent to
    SURFACE WATERS
    AEROBIC AND ANEROBIC TREATMENT PROCESSES,
    FOLLOWED 3Y PHYSICAL CHEMICAL TREATMENT
    SHOULD 3E INVESTIGATED IN THE TREATMENT
    OF HYDRAPULPING WASTESTREAMS (TABLE 1)
    Figure 1
    224
    

    -------
    scauaaca watg?
    EFTUJENT
    TO POT*
    PRIMARY
    G-AWIflEf?
    EFFLUENT TO
    SECONQARY
    vC-ARIFIEH .
    CARSON
    ABSORPTION
    C3UJMN3
    FLOCCUOTOR
    FLOCCULATCR
    OVJAU. MEDIA
    FILTERS
    ACTIVATED
    SLUOGE
    CARSON
    AOSORPT1CN
    COLUMNS
    CXJAi_ MEDIA
    FILTERS
    SURFACE WATERS
    BOTH AEROBIC AND PHYSICAL CHEMICAL TREATMENT PROCESSES
    SHOULD 3E INVESTIGATED IN THE TREATMENT OF
    SC5U3BER WATERS (Table 2)
    Figure 2
    

    -------
    rrmxrsis •a*te5T*cw*
    i
    AHA£POQlC
    . CONTACT,
    SCC* MOT A TUX
    IC0IMO4TATIOM
    1MTCRM tD» + TZ
    ri AOinra f
    m ruiMCDiAre
    Voffline* V
    njCOJLATOB
    CAM BON AOSOftPTION
    OUJMKS
    crn-ucwT to
    su*FACt «ATors
    AEROBIC AND ANAEROBIC TREATMENT PROCESSES, OPERATED
    IN SERIES AND IN PARALLEL, SKCCJLD 3E INVESTIGATED
    IN THE TREATMENT OF PYROLYSIS WASTESTREAMS (Table 3)
    Figure 3
    226
    

    -------
    OU3C3TOI m.7*ATE
    AOIOfflC
    *UOT
    ruant
    PRIMARY
    PRIMARY
    cu#ir\a*
    04fiX4lCAl
    OUAi. MCStA
    HUTS?
    intepm court
    O^ARtHS?
    GAR80* A ~SORPTION
    CSCUMNS
    ETFUUCNT TO
    SURFACT WATOW
    PUW4T
    OJAC MQIA
    OUTERS
    
    
    CARSON aosor*tioh
    COUJMNS
    	
    	
    CFFUJClT TO 3URFACZ WATERS
    AEROBIC AND PHYSICAL CHEMICAL TREATMENT PROCESSES
    SHOULD 3E INVESTIGATED IN THE TREATMENT
    OF DIGESTER WASTESTREAMS (Table 4)
    Ficiire 4
    227
    

    -------
    TECHNICAL REPORT DATA
    (Please read Instructions on the reverse before completingj
    I.SEPORTNO. 2.
    3. RECIPIENT'S ACCESSlOl^NO.
    a. title amo subtitle
    Proceedings from a Technical Conference on
    Waste-Co-Energy Technology Update - 1980
    5. REPORT DATE
    September, 1980
    6. PERFORMING ORGANIZATION COOE
    G-8290
    7. AUTHOR(S)
    G. Ray Smithson, Jr.
    8. PERFORMING ORGANIZATION REPORT NO.
    9. PERFORMING ORGANIZATION NAME ANO AOORESS
    Battelle Columbus Division
    505 King Avenue
    Columbus, Ohio 4 3201
    10. PROGRAM ELEMENT NO.
    11. CONTRACT/GHANT no.
    R 806 653 010
    12. SPONSORING AGENCY NAME AND AOORESS
    Incineration Research Branch
    Industrial Pollution Control Division
    U.S. Environmental Protection Agency
    Cincinnati, Ohio 45268
    13. TYPE OF REPORT ANO PERIOD COVERED
    Proceedings
    14. SPONSORING AGENCY COOE
    15. SUPPLEMENTARY NOTES
    16. ABSTRACT
    The Technical Conference on Waste-to-Energy Technology Opdate-1980 was held ac
    Cincinnati, Ohio, on April 51 and 16, 1980. The purposes of the technical conference
    were:
    o To review the status of relevant research and
    development activities being supported by U.S.
    EPA's Industrial Environmental Research Laboratory
    at Cincinnati, Ohio.
    o To consider the most effective means for the
    commercial exploitation of the results of this
    research.
    o To review areas for future research and to recommend
    strategies for the implementation of such research.
    The conference was presented in three technical sessions; these are Conversion
    Processes, Combustion, and Environmental Assessments and Pollution Control Technology
    These proceedings incorporate copies of the papers presented by the conference
    speakers.
    17. KEY WORDS ANO DOCUMENT ANALYSIS
    a. DESCRIPTORS
    b.IDENTIFIERS/OPEN ENDED TERMS
    c. COSATi Field/Group
    Was te-to-Energy
    RDF
    DRDF
    Energy Recovery
    Waste Disposal
    
    
    i3. DISTRIBUTION STATEMENT
    19. SECURITY CLASS (This Report)
    UNCLASSIFIED
    21. NO.PAGES
    20. SECURITY CLASS (This page)
    11. PRICE
    	
    EPA Form 2220-1 (9-73)
    

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