United States
Environmental Protection
Agency
Atmospheric Sciences
Research Laboratory
Research Triangle Park NC 27711
Research and Development
EPA/600/S3-86/029 June 1986
&EPA Project Summary
Investigation of the Formation
of a Portland Cement Plant
Detached Plume
James L. Cheney and Kenneth T. Knapp
Gaseous and participate source emis-
sion samples were collected at a Portland
cement production plant to determine the
cause of a detached high-opacity plume.
During this sampling program, gas and
solid samples were taken from the various
stages of the cement plant process to
determine the source of potential plume
reactants.
The results of the source and process
sample analyses indicated that the cause
of the visible plume was ammonium chlor-
ide, formed from gas-phase ammonia and
hydrochloric acid as the plume cooled.
Results from the source sampling indi-
cated a significant part of the collected
paniculate sample was ammonium chlor-
ide. In-stack paniculate sampling showed
that at stack temperatures, the ammonia
and hydrochloric acid reactants were in the
gas phase in the stack but formed am-
monium chloride particles in the extractive
sampling probes.
Analysis of the process solid samples in-
dicated no significant ammonia was emit-
ted from the kiln or derived from the
limestone feed. However, analysis of the
shale feed indicated the presence of am-
monium that is released upon heating. The
hydrochloric acid is probably formed from
the chloride ion content of the coal, lime-
stone, and feed material.
This Project Summary was developed
by EPA's Atmospheric Sciences Research
Laboratory, Research Triangle Park, NC, to
announce key findings of the research pro-
ject that is fully documented in a separate
report of the same title (see Project Report
ordering information at back).
Introduction
This project summary discusses the
results of a study conducted to determine
the cause of the formation of a highly visi-
ble detached plume at a Portland cement
production plant. The study was initiated
in response to a Technical Assistance re-
quest from EPA's Region VIII. A two-week
source and process sampling study was
conducted at the Portland cement produc-
tion plant, located in Rapid City, South
Dakota. Along with three wet process
kilns, the plant has a dry-process, coal-
fired, clinker production facility. The dry
process involves pulverizing limestone and
shale into blend silos which are subse-
quently fed into the kiln. The kiln feed is
introduced into the kiln -through a four-
stage heat exchanger, where the solids are
preheated by the flow counter to the coal-
fired kiln emissions level. Within this heat
exchanger the kiln gases are cooled from
a nominal 2000 °F to 700 °F and the solids
are heated to a nominal 1500°F at the
feed entrance of the kiln.
After preheating the kiln feed solids, the
kiln emissions can proceed out the 10O-ft
stack by either of two routes. One route
is through the Loesch Mill, which pulver-
izes the raw feed. The other route by-
passes the mill while it is not operating.
The operation mode when the mill is run-
ning is designated the mill on mode (MON)
and when not, the mill off mode (MOF).
Emissions then pass through a baghouse
and exit the stack. During both these
modes, opacity within the stack is a
nominal 10%. Just subsequent to stack
exit, the emissions become highly visible
by some particle-forming mechanism. The
purpose of this study was to determine
the nature and cause of the visible detach-
ed plume. The source sampling was con-
ducted by the personnel arjd in-house con-
tractor support of the Stationary Source
Emissions Research Branch of EPA at
Research Triangle Park, NC.
-------
Sampling Methods
The sampling involved seven days of
operation; four in the MOF mode, and
three in the MON mode. Particulate and
gaseous emissions were measured with a
variety of in-stack and extractive sampling
methods including; a modified version of
the EPA Reference Method 5 (MM5); pro-
totype particulate gaseous systems
(PAGS); a seven-stage particle sizing im-
pactor; and various filter medium samples
for particulate characterization. The MM5
train was used to measure gaseous sulfur
dioxide, ammonia, chloride, and fluoride by
various impinger solutions. The PAGS sys-
tems were run in simultaneous pairs and
were used to measure particulate and gas-
eous ammonium, chloride and fluoride
components of the emissions.
The particle-sizing samples were taken
with a seven-stage. University of Wash-
ington, Mark IV impactor with either steel
plates or quartz filter plates for particle col-
lection. Samples were taken both in and
out of the stack by an extraction probe.
Glass fiber, Teflon and quartz character-
ization filter samples were collected with
an extraction system. The plant process
was sampled extensively during both oper-
ation modes, and samples of solids from
the mill, kiln, baghouse, and heat ex-
changer were collected.
Results
A total of 11 MM5, 21 PAGS, 14 im-
pactor, and a large number of characteriza-
tion filter samples were collected during
the sampling period. Six sets of simul-
taneous MM5 and PAGS samples were
collected during the MOF mode and five
sets were collected during the MON. A
white precipitate in the probes, which was
difficult to recover quantitatively with ace-
tone and brush washings, was recovered
from the particulate sampling systems.
Nearly all of the particulate mass recovered
by the MM5 sampling systems was lo-
cated in these probe wash fractions. Filters
showed insignificant weight gains and
many showed weight losses. For the MM5
samples, chemical analysis of the probe
wash residues indicated that from 4 to as
much as 83 percent of the residue was
NH4CI. Probe washes also composed a
significant fraction of the mass collected
with the PAGS systems. As with the MM5
samples, a large part of some of the PAGS
probe washes was NH4CI.
Emission rates of particulate matter were
calculated for both. MOF and MON modes
of operation from the MM5 and PAGS sam-
ples. Table 1 provides the total mass emis-
sion rates (Ib/h) of particulate matter and
Table 1. Summary of MM5 and PAGS Emission Rates (Ib/h)'
Mode Total Particulate
Adjusted Particulate
MOF
MON
MM5
36.2(4)
18.2(4)
PAGS-A
23.1(4)
14.7(1)
PAGS-B
30.7(4)
20.4(2)
MM5
17.3(4)
12.4(4)
PAGS-A
17.4(6)
12.5(2)
PAGS-B
18.0(5)
13.8(3)
"Numbers in parentheses indicate the number of measurement results used to determine the
accompanying average.
the emission rates adjusted to show the
absence of the NH4CI detected in the
residues.
The large variations observed between
the sampling methods for the unadjusted
rates (total particulate) are due to the spo-
radic formation of NH4CI in-the sampling
probes. The larger contribution of probe
NH4CI during the MOF mode is due in part
to the higher temperature of the baghouse,
which was 480 °F in contrast to the
342 °F temperature of the MON mode.
Only a limited amount of information
could be derived from the impactor and
characterization samples since in-stack
sampling did not collect the gas phase
NH3 or HCI, and the extraction collection
lacked the NH4CI lost in the sampling
probe.
Process samples were collected for sub-
sequent composition studies. Analysis of
the Loesch Mill, kiln feed, and baghouse re-
turn confirmed the presence of NH3 in the
emissions and indicated less particulate-
phase NH4CI in the baghouse solids dur-
ing the high temperature MOF mode than
during the MON mode. These samples,
along with raw product feed samples,
were analyzed for NH3 by washing and
filtering with 0.1 N H2SO4. Very little NH3
was detected for the raw feed by washing;
however, heating the raw feeds in an appa-
ratus custom built to collect emitted gases
resulted in the liberation of NH3 from the
shale. It was determined that heating the
shale to a minimum temperature of 900 °F
for 1 h would liberate the NH3 in the
shale. The shale liberated an average po-
tential of 51.4-ppm NH3 based on a wt/wt
basis of undried shale. Assuming a raw
feed rate of 224,000 Ib/h, there is a poten-
tial for an emission of 4.1 Ib/h of NH4CI if
all NH3 is emitted as NH4CI.
Conclusions
Two approaches to solving the detached
plume problem are suggested as a result
of this study: (1) the raw shale should be
heated prior to its milling to liberate the
NH3 or (2) the baghouse temperature
should be lowered such that particulate
NH4CI would form and be collected with
the other baghouse solids, and this mater-
ial should be returned to a wet process
system instead of the dry process system.
-------
The EPA authors, James L. Cheney (also the EPA Project Officer, see below) and
Kenneth T. Knapp are with the Atmospheric Sciences Research Laboratory,
Research Triangle Park, NC 27711.
The complete report, entitled "In vest igat ion of the Formation of a Portland Cement
Plant Detached Plume," (Order No. PB 86-194 420/AS; Cost: $ 16.95, 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:
Atmospheric Sciences Research Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OM 45268
.
Official Business
Penalty for Private Use $300
EPA/600/S3-86/029
PS
AGENCV
CHICAGO
------- |