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United States
Environmental Protection
Agency
Hazardous Waste Engineering
Research Laboratory
Cincinnati OH 45268
Research and Development
EPA/600/S2-85/032 May 1985
&ER& Project Summary
Demonstration Test of Refuse-
Derived Fuel as a Supplemental
Fuel in Cement Kilns
Cliff R. Willey and Carl S. Weinberger
Air emission tests consisted of three
sampling runs with coal only and three
runs with coal and Refuse Derived Fuel
(RDF). Sampling was done at the stack
following gas cleanup by electrostatic
precipitators. Analysis was done for
particulates (EPA Method 5), SO,
(Method16), chlorides (as HCI) and NO,.
A precipitator malfunction and cleanout
occurred just prior to the tests.
Particulates averaged 0.022 gr/dscf
burning coal and 0.059 gr/dscf burning
coal and RDF. Chlorides increased
slightly; NO, was not significantly af-
fected. SO, results appeared to be
affected by the precipitator cleanout.
Dust buildup in the ESPs was noted
when burning RDF, indicating that
some adjustment to the precipitators
may be needed when using RDF to
achieve maximum particulate cleanup
of the gas stream.
The full report also discusses RDF
preparation equipment and RDF feed
equipment developed for the tests.
This Project Summary was developed
by EPA's Hazardous Waste Engineering
Research Laboratory, Cincinnati, OH,
to announce key findings of the research
project that is fully documented in a
separate report of the same title (see
Project Report ordering information at
back).
Introduction
The cement manufacturing industry
represents an attractive opportunity to
recover energy from municipal solid
waste. It consumes significant amounts
of energy, 457 trillion Btu per year, and
includes 49 plants with capacities to use
over 380 tons per day of refuse derived
fuel. The industry also involves a process
in which ash and other products of
combustion become part of the manufac-
tured project, thus minimizing the re-
quirement for ash disposal and reducing
the need for costly additional air pollution
control equipment.
In spite of this attractiveness, progress
towards the use of RDF in the cement
industry has been slow, tempered by
industry caution on one hand and a lack of
test information on the other. None of the
tests in the United States has involved
more than 5 test days.
In 1975, when discussions were begun
with the Lehigh Portland Cement Com-
pany regarding potential use of refuse
derived fuel in the production of cement,
it became apparent that even though
there was interest, there also was con-
cern about the untried nature of the fuel.
This concern included:
• ability to supply and feed RDF continu-
ously,
• firing characteristics and ability to burn
RDF in suspension,
• effect on RDF chemical composition
and variations in composition on ce-
ment quality and chemistry,
• long-term effects on RDF on kiln
operation and cement production, and
• effect on air emissions.
The following test program was devel-
oped to address these concerns:
1. RDF would first be tested at a coal-
fired, lightweight shale kiln. The
advantage of such testing was the
experience gained with the burning
characteristics of RDF and with the
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reliability of RDF feed equipment.
As part of the test agreement, the
feed equipment was expected to
demonstrate 7 days of continuous
operation before tests could begin
at the cement plant.
2. When the lightweight aggregate
test was satisfactorily demonstra-
ted, RDF feed equipment would be
set up at a cement plant to produce
test quantities of cement for anal-
ysis (2 to 3 day test).
3. Again, based on satisfaction with
the production step, an extended
burn test involving air emission
measurements would be run.
Conclusions
• Satisfactory Type I and Type II cement
were produced burning supplemental
refuse derived fuel with coal. Physical
properties such as strength and set
time were within acceptable limits.
Chemical composition of cement pro-
duced with RDF and coal was not
significantly different from cement
produced with only coal. No alteration
of the infeed raw material mix was
needed to adjust for differences in
chemical makeup caused by substitu-
tion of RDF for coal. These results
apply to the test conditions in which up
to 37 percent of the heat was supplied
by RDF.
• Fluff RDF (as well as the primary fuel)
must burn in suspension to avoid
causing low oxygen (reducing) condi-
tion at the kiln bed and subsequent
unacceptable changes in cement
chemistry. For the conditions of this
test, RDF would require secondary
shredding to a size 95 percent less
than 2.5 cm (1 in.) for suspension
burning. More or less finely shredded
RDF may be required for different kiln
conditions, feed techniques, and feed
rates.
Although stack emission tests were
probably affected by a precipitator
outage and cleaning prior to the test
period and must be interpreted with
caution, none of the emissions tested—
particulates, chlorides, nitrous oxides,
and sulfur oxides—appeared to present
a serious problem. Ash buildup in the
ESP with time after starting to burn
RDF indicated RDF may have affected
the properties of the dust-fly ash mix
collected by the ESPs and that some
adjustment in operating conditions
might be required if RDF were burned
on a continuous basis.
• Fluff RDF can be stored in transfer
trailers and reliably fed from the
trailers provided: (a) the RDF is only
moderately compacted in the trailers;
(b) lump breakers or some other means
is used to refluff and even out the flow
of RDF; and (c) the rate of trailer
unloading and the speed of the feed
conveyors are controllable.
Recommendations
Long-term tests of RDF as a cement kiln
fuel should be continued to establish
industry confidence in the use of this fuel.
The best approach may be the develop-
ment of a semi-automated feed station
for continuous RDF fuel use at a cement
manufacturing plant.
Cliff R. Willey and Carl Weinberger are with the Maryland Department of Natural
Resources, Annapolis, MD 21401.
Michael Black and Robert Olexsey are the EPA Project Officers (see below).
The complete report, entitled "Demonstration Test of Refuse-Derived Fuel as a
Supplemental Fuel in Cement Kilns." (Order No. PB 85-180 842/AS; Cost $10.OO,
subject to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Hazardous Waste Engineering Research Laboratory
U.S. Environmental Protection Agency
Cincinnati, OH 45268
U.S. GOVERNMENT PRINTING OFFICE: 1985-559-016/27058
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
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