United States
Environmental Protection
Agency
Industrial Environmental Research
Laboratory
Research Triangle Park NC 27711
Research and Development
EPA-600/S2-83-101a/b Nov. 1983
Project Summary
A Study of PCB Destruction
Efficiency and Performance for a
Coal-Fired Utility Boiler
Frank C. Whitmore and James D. Barden
The report gives results of an
evaluation of the adequacy of a large
coal-fired utility boiler for disposal of
oils containing 50-499 ppm of poly-
chlorinated biphenyls (PCBs) under the
conditions set by the PCB Disposal
Regulations. TVA's Widows Creek
Boiler No. 1 was the unit tested. In
these tests, all effluent streams were
sampled and analyzed to determine
representative values of Destruction
Efficiency (DE) for this technology. The
average PCB content of the oil used was
215 ppm.
Test results showed that, at the
maximum contaminated oil feed rate of
454 L/min (120 gal./hr) utilized, there
was no discernible effect on boiler
efficiency. Further, analyses showed
that PCB levels were below the
detection limits that had been
established in the laboratory.
This Project Summary was developed
by EPA's Industrial Environmental Re-
search Laboratory. Research Triangle
Park, NC, to announce key findings of
the research project that is fully docu-
mented in a separate report of the same
title (see Project Report ordering infor-
mation at back).
Introduction
The regulations that control the
disposal of PCBs and PCB-contammated
materials distinguish between required
disposal procedures according to PCB
concentration. Materials containing
more than 500 ppm of PCBs must be
disposed of in an incinerator that has
been specifically tested for its ability to
dispose of PCBs; however, materials that
contain less than 50 ppm of PCBs may be
used as conventional fuels in boilers.
High-heating-value materials (e.g., used
transformer oil) containing between 50
and 500 ppm of PCBs can only be burned
in high efficiency power boilers (or in PCB
incinerators). It had been a matter of
some concern that the ability of such high
efficiency boilers to produce acceptable
destruction efficiencies (DE) had not been
determined in representative systems.
Tests on several oil-fired power boilers
have shown that a DE of greater than
99.9% (as required by the regulations)
can be obtained without degrading boiler
performance. There is, however, a
significant difference between oil-fired
and coal-fired boilers. With oil, the
non-combustible cojnponent of thefuel is
relatively small, so that the particulate
components of the combustion gases
represent an insignificant contribution.
However, with coal, there is a significant
non-combustible (ash) content that is
often as high as 15%. There is, then, the
possibility that PCBs attached to the fly
ash can survive passage through the high
temperature regions of the boiler
resulting in unacceptable DE values The
tests performed in this program
investigated this possibility in a
representative coal-fired system
After background measurements that
also a Mowed the determination of the rate
of production of fly ash, three PCB-
injection experiments were carried out at
TVA's Widows Creek Boiler No. 1. Unit 1 's
fire box is divided into two regions by
water tubes running vertically through it.
This results in separation of the flue
gases into two streams, referred to as the
A and B sides. With two streams, it was
possible to feed on one side of the boiler
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and use fly ash and flue gas samples from
the other side as background. The three
experiments were: (1) feed on A side,
sample both sides; (2) feed on B side,
sample both sides; and (3) feed and
sample both sides.
The flue gases, the fly ash, and the
PCB-contaminated feed stock were all
sampled for each test run. The flue gas
was sampled downstream of the electro-
static precipitators. Each experiment
lasted long enough to allow two samples
to be taken on each plenum.
On the basis that both the flue gases
and the fly ash could have contained PCB
concentrations just below the quantify
able level, the minimum (worst-case)
destruction efficiency can be determined.
The average over six experiments (two
from each feed configuration) showed a
DE of 99.95%. Because the actual
concentrations of PCBs were probably
significantly below the detection limits,
this value appears to represent a
minimum vajue for the DE in the system.
This experiment shows that the
technology represented by Widows Creek
Boiler No. 1 meets the stated
requirements of a 99.9% DE for
destruction of PCBs in waste oil in the 50-
499 ppm range.
3. Disposal operations can be carried
out with minimal risk to personnel
or facility.
F. C. Whitmore and J. D. Barden are with Versar, Inc., Springfield. VA 22151.
David C. Sanchez is the EPA Project Officer (see below).
The complete report consists of two volumes, entitled "A Study of PCB Destruction
Efficiency and Performance for a Coal-Fired Utility Boiler:"
"Volume 1. Test and Evaluation," (Order No. PB 84 110 147; Cost: $11.50,
subject to change)
"Volume 2. Test Protocol," (Order No. PB 84-110 154; Cost: $11.50, subject
to change)
The above reports 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:
Industrial Environmental Research Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
•frUS GOVERNMENT PRINTING OFFICE 1983-659-017/7221
Conclusions
Conclusions drawn from these experi-
ments include:
1. A coal-fired power boiler can
effectively destroy low level PCB-
containing waste without compro-
mising boiler performance.
2. Costs associated with such
disposal should be minimal; in fact,
such disposal should result in sig-
nificant savings over other options.
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
Official Business
Penalty for Private Use $300
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