United States
Environmental Protection
Agency
Environmental Sciences Research
Laboratory
Research Triangle Park NC 27711
Research and Development
EPA-600/S3-83-102 Dec. 1983
&ER& Project Summary
Formation of a Detached
Plume from a Cement Plant
James L Cheney, William D. Conner, Roy L Bennett, Donald L Duke, Carole L
Walters, and Kenneth T. Knapp
A coordinated study of process, source
emissions, and plume sampling was
conducted at a coal-fired cement pro-
duction plant. Both source and plume
sampling consisted of particle and gas
measurement and characterization. Par-
ticulate sampling of both the source and
plume addressed particle size, amount,
and composition. Particles were ana-
lyzed by scanning electron microscopy,
x-ray fluorescence spectroscopy, and
chemical means. Gas sampling of both
the source and plume involved conven-
tional source sampling methods as well
as procedures adapted to this specific
measurement program. Plume opacity
was measured by visual observation
and a LIDAR system.
Comparison of the results from the
plume and source measurement indi-
cated the formation of the plume was
the result of the reaction of ammonia
and hydrochloric acid. The formation of
ammonium chloride occurred within
the same set of reaction parameters as
independent laboratory studies'had
previously indicated.
The results of electron microscopy
analysis for one of the plume samples
indicated an NH4CI particle size of < 0.4
fjm. When an estimation of the amount
of these sized particles was compared
to source particle sizing measurements,
a 50 to 100% increase in such inhalable
particulates was occurring within the
plume, at less than 18 stack diameters
from the exit.
This Project Summary was developed
by EPA's Environmental Sciences 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
This report discusses an in-depth study
of a coal-fired cement production plant to
determine the nature of the formation of a
visible plume from the gases emitted
from the stack. The plant has the capa-
bility of operating on either a regular
mode or a bypass mode. The visible plume
formed each time the plant operated in
the bypass mode. During the regular
mode, the off gases from the coal-fired
kiln passed through the raw product
grinding mill and a recovery electrostatic
precipitator (ESP) prior to their exit to the
atmosphere. Duri ng the bypass mode, the
kiln gases were rerouted around the mill
and through a cooling tower, after which
they were passed through the ESP and
vented to the atmosphere. During both
operating modes, source measurements
indicated that the plant was well within
compliance for both opacity and panicu-
late grain loading.
A 1-week (5-day) sampling program
was conducted at the Lehigh plant at
Leeds, Alabama, in May 1981. The sampl-
ing addressed both source emissions of
gases and particles and plume sampling.
Source emissions were sampled by con-
ventional extractive methods to determine
the concentrations of S02, NH3, HCI, and
NOx as well as particulate mass emission
rates, particle size, and particle composi-
tion. Gaseous HCI, NH3, S02, CO and C02
were also measured with an optical
cross-stack procedure. The plume sampl-
ing was performed with tethered balloons
and various filters. The filters, which
were connected to a pump box on the
ground, were analyzed for such gases as
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HCI, NH3, S02, and the particles were
analyzed for SO4=, S03=, CI", NH3, by x-
ray fluorescence spectroscopy, and scan-
ning electron microscopy. Opacity meas-
urements for the plume at and near the
location of the balloon sampling location
were performed with both a LIDAR system
and by visual observation.
Results
Inclement weather and plant operating
problems severely limited the time during
which sampling of the bypass mode
plume could be performed. However,
adequate data were established to con-
clude how the particles were formed in
the plume.
These data included:
1) In-stack measurements indicated
that particulate NH4+ and CI* emis-
sions of 0.68 (expressed as NH3) and
7.21 (expressed as HCI) Ib/hr were
emitted and that ~ 85 percent of the
NH3and ~ 50 percent of the HCI were
emitted as gases. A second improved
HCI reference method indicated — 80
percent of the HCI was emitted as gas
phase.
2) The mass emission rate of particu-
lates from the stack was 7.7 and 15.4
Ib/hr from two samples acquired. X-
ray fluorescence analyses of the
particles indicated their main com-
ponents as Ca, Si, K, Fe, S, and Al. A
Pilat impactor sample indicated that
56 percent of the total particulate
catch was on the backup filter where
the particles were less than 0.4 /urn in
size.
3) Gas and particle composition of the
plume were determined with a three-
stage filter designed to collect parti-
cles and gaseous HCI, NH3 and SC<2.
The second filters following the front
prefilter were chemically impreg-
nated to absorb gaseous components
passing through the particulate filter.
Analyses of all three filters indicated
a total catch of 1.86,1.13, and 12.5/u
moles of HCI, NH3, and S02, respec-
tively. The first of the three filters
was assumed to collect particles
only. The first filter collected 1.25,
0.75, and 0.08 fj moles of HCI, NH3,
and S0<~, respectively. This indicated
that ~ 40% of the HCI and NH3 had
reacted to form particles but that very
little (~ 7 percent) of the S02 had
been converted_or was contained as
particulate S04=.
4) Scanning electron microscopy of two
plume samples acquired during the
high opacity situation indicated a
particle size range of 0.2 to 0.6 yum
for both samples. In one of the
samples a predominant number of
particles contained CI* and were
volatile in the electron beam. It was
assumed that NH4CI was the basic
particle component. The second
sample contained a large number of
particles with K and S. There were no
significant particles containing CI" in
this sample. These particles were
assumed to contain I^SCu.
5) Opacity measurements by the LIDAR
system and by visual observation
agreed well and ranged from less
than 5 percent near the stack exit to
as high as 41 percent within 50 m of
the exit.
Conclusions
The change from an invisible plume
just above the stack to a highly opaque
plume ~ 50 m from the stack indicates
some kind of particle formation.
The change in composition between in-
stack and plume samples showed a
conversion of gaseous NH3 and gaseous
HCI to particulate matter containing NH4+
and CI". That this particulate matter was
indeed NH4CI was supported by electron
microscopy. There was also some evi-
dence of S04= formation. The increase in
particulate matter in the plume within 50
m downwind of the stack exit resulted in
an estimated double amount of fine or
inhalable particulate matter than that
indicated by the source measurements.
It was concluded from the data that the
visible plume formed during bypass mode
operation was the result of fine particle
formation, predominantly NH4CI, but with
some sulfite-sulfate salt formation, prob-
ably a result of water droplet chemistry.
The EPA authors, James L. Cheney (also the EPA Project Officer, see below),
William D. Connor. Roy L. Bennett, Donald L. Duke, Carole L. Walters, and
Kenneth T. Knapp are with Environmental Sciences Research Laboratory,
Research Triangle Park, NC 27711.
The complete report, entitled "Formation of a Detached Plume from a Cement
Plant," (Order No. PB 84-120 187; Cost: $11.50. 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:
Environmental Sciences Research Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
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