United States
Environmental Protection
Agency
Air and Energy Engineering
Research Laboratory
Research Triangle Park NC 27711
Research and Development
EPA/600/S2-86/068 Nov. 1986
oEPA Project Summary
Microprocessor Control of
Rotogravure Airflows
D. R. Rosen and M. R. Wool
This report discusses the technical
and economic viability of using
microprocessor-based control technol-
ogy to collect volatile organic com-
pound (VOC) emissions from a paper
coating operation. The system evalu-
ated is operating at the James River
Corporation rotogravure printing facil-
ity in Kalamazoo, Michigan.
The microprocessor-based control
system monitors and controls both the
airflow rate and vapor concentration
level within the printing press dryers. It
enables incineration of the VOC emis-
sions in the plant's existing steam
boiler and also saves energy by reduc-
ing the amount of dryer and room air
that must be heated. The general con-
cept, performance levels, and economic
parameters for the James River VOC
control system demonstrate the poten-
tial advantages of the technology for a
wide range of applications.
James River looked at three methods
to collect and destroy VOC emissions
for their rotogravure operation: solvent
recovery, thermal destruction in a dedi-
cated incinerator, and thermal destruc-
tion in an existing onsite boiler. For
James River, the use of their existing
boiler is the best option even though
they were required to add equipment to
collect, transport, and control the ro-
togravure airflows.
The microprocessor and sensors
which are an integral part of the emis-
sion control system enable James River
to safely reduce the flowrate of air
through their presses. The sensors
measure the air pressure and VOC con-
centration in the press dryer exhaust,
and the microprocessor adjusts fan
speeds to maintain proper flowrates.
Over a 3-day period, operating data
were recorded to evaluate the flow sys-
tems performance. With the microproc-
essor in operation, James River ex-
pected to see flowrates of less than
30% of the flow prior to conversion.
This expectation was confirmed by
measurements taken during the test
period. Despite the flowrate reduction,
concentrations of VOCs remained
safely below the lower flammability
limit. These tests showed that a micro-
processor system, appropriately tied to
an incinerator or boiler, is an effective
way to address federal and state VOC
emission standards for the paper print-
ing industry.
This Project Summary was devel-
oped by EPA's Air and Energy Engineer-
ing Research Laboratory, Research Tri-
angle Park, NC, to announce key
findings of the research project that is
fully documented in a separate report
of the same title (see Project Report or-
dering information at back).
Introduction
The microprocessor-based control
system monitors and controls both the
airflow rate and vapor concentration
level within the printing press dryers.
The system in this study incinerates
VOC emissions in the plant's existing
steam boiler and also saves energy by
reducing the amount of dryer and room
air that must be heated. The general
concept, performance levels, and eco-
nomic parameters for the VOC control
strategy demonstrated the potential ad-
vantages of microprocessor control
technology for a wide range of applica-
tions.
This study discusses the technical
and economic viability of using
microprocessor-based control technol-
ogy to collect volatile organic com-
pound (VOC) emissions from a paper
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c6ating operation. The system evalu-
atecj^s operating at the James River
Corporation rotogravure printing facil-
ity^ n Kalamazoo, Michigan.
System Installation Objective
VOC emissions react in the atmos-
phere to form ozone and other undesir-
able constituents of smog. As a result,
James River Corporation initiated a pro-
gram to control atmospheric emission
of VOCs from their rotogravure printing
operation. The objective of installing
the control system was to collect and
destroy VOC emissions by the most
cost-effective approach.
System Elements
A microprocessor-based system was
selected by the James River Corpora-
tion to safely lower dryer airflows and
permit VOC incineration in an existing
process boiler. The microprocessor sys-
tem automatically controls exhaust fan
speeds to minimize airflow rates while
maintaining safe VOC concentrations.
The net reduction in flow allows the
existing process boiler to accept all ro-
togravure dryer emissions as combus-
tion air.
The major elements of the VOC con-
trol and collection system at the James
River plant are:
A microprocessor based computer/
controller.
A continuous analyzer to determine
when VOC concentrations ap-
proach the lower flammability limit
(LFL).
Variable speed motor drives.
Pressure transducers.
Diversion dampers.
Operator display panel.
Several other modifications and sub-
systems were also necessary to imple-
ment VOC destruction using the exist-
ing plant boiler. Ductwork was installed
between a transfer fan and the boiler
forced draft fan. A new forced draft fan
was installed because the existing fan's
bearings would be damaged by the
VOCs in the press exhaust aiu Modifica-
tions were also necessary to some press
decks in order to provide better sealing,
thereby allowing operation at reduced
fan speeds.
Performance Data Acquisition
As a part of the VOC control system,
process parameters are monitored by
permanent instrumentation. However,
the existing system has no provisions
for data storage. Therefore, process
parameters of interest to this study
were recorded during the test period by
a temporary data acquisition system.
The system consisted of a data interface
unit and a personal computer. A floppy
disk and thermal printer provided for
hardcopy data output and storage.
Performance Results
Table 1 shows the effect of the VOC
control system on the flowrate of air
through the four presses considered in
this study and confirms that the system
operated as expected during the data
acquisition period. Measured airflow
rates were close to the expected values,
which represented a 71% decrease in
airflow when compared to the precon-
version values. Despite the decrease in
airflow rates, the percentage LFL re-
mained well within acceptable and safe
values.
Equipment Cost and Energy
Savings
This installation of a microprocessor
control system enables the plant's exist-
ing boiler to be used for VOC destruc-
tion. James River determined that use
of the existing boiler was the most cost-
effective method of addressing their
VOC emission control requirements. In
addition, significant cost savings result
from operation of the system because
the quantity of collected air was signifi-
cantly reduced. These savings include:
Reduction in energy demand for
dryer air heating due to reduced air
exhaust rates.
Recovery of thermal energy in
press exhaust by using the exhaust
as air for boiler combustion (presi
exhaust averages 23°C above ambi
ent air temperatures annually).
Recovery of calorific value of VOCs
incinerated in the boiler.
Table 2 summarizes installed cost
for the conversion project at the Jame!
River plant. Annual energy savings an
summarized in Table 3.
Safety
The control system incorporates sev
eral safety features and interlocks, in
eluding:
LFL analyzer failure (flameout) de
tection.
High LFL level alarm and pres:
shutdown.
Loss of deck exhaust flow.
No LFL analyzer failures occurred dur
ing the data collection period, nor wen
acceptable percentage LFL levels ex
ceeded. Based on the review of the sys
tern design and operating data, thesi
safety features operated as intended.
Conclusions
This study shows that rotogravur
printing operations can benefit from th
microprocessor-based control techno
ogy discussed in this report. Economi
benefit accrues due to the reduction i
process air exhaust volumes whic
must be processed by a collection syi
tern or an incinerator or heated by
process dryer. The techniques used t
monitor and control VOC concentn
tions and to allow lower air volumes at
broadly applicable to processes whic
Table 1. VOC Collection System Performance Summary
After conversion
Press
No.
3047
3049
3051
3052
rnor to conversion
Exhaust flowrate
scfm
(l/s)
20,000
(9,378)
25,000
(11.723)
7,000
(3,282)
25,000
(11,723)
77,000
(36,106)'
Expected exhaust
flowrate
scfm
(l/s)
6,000
(2,813)
4,000
(1,876)
4,200
(1,969)
8,000
(3,751)
22,200
(10,409)"
Measured exhaut
flowrate
scfm
(l/s)
6,105
(2,863)
3,839
(1,800)
4,245
(1,990)
7,900
(3,704)
22,089
(10,357)a
"Totals have been rounded off for consistency.
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Table 2. Conversion Cost Summary1985 Dollars
Category
Total
($1000s)
Control System
1. Microprocessor control system3
2. LFL Analyzers"
Subtotal
Engineering
3. Preinstallation analysis and system design
Collection and Transport System0
t. Ducting and press modifications
5. Boiler modifications
Subtotal
Total
295
145
440
100
720
300
1020
1560
'Includes computer, pressure transducers, and drives.
'Includes two FID analyzers, eight-channel manifold, and sample pump.
'Items 4 and 5 are unique costs, required only because James River was ducting to a boiler. If
the plant had an existing incinerator, then these costs would not be applicable.
"able 3. Annual Fuel Energy Savings
Air reduction
Units savings
3tu x Jfl6 34,250
loules x JO9 36,727
Air preheat
savings
12,670
13,364
Calorific
value
24,930
26,296
Total
71,850
75,787
use heated air in the presence of sol-
vents or other materials. The system re-
duces plant operating and pollution
control costs by reducing fuel required
to heat the facility air or the air used in
the process.
The application of microprocessor
technology studied at James River is an
extension of the technology from metal
coating (i.e., painting) application. This
study proved that the technology is ap-
plicable to the paper coating industry
and can provide economic benefits
through the reduction in energy re-
quirements for a printing process. Al-
though the amount of energy savings
and the cost of plant modifications will
be different for each application, energy
savings, in most cases should offset the
capital cost of the plant modifications
within a short time. Additional reduc-
tions in operating costs will also be real-
ized due to the reduced airflows.
A potential user of a microprocessor
control system should review the re-
sults of this study to assess if similar
energy and emission control benefits
are possible in other applications of in-
terest. In general, any application where
airflows are used to carry away VOCs
could be improved through active con-
trol of both airflow rates and VOC con-
centrations. Depending on the applica-
tion, the b*st cleanup approach may be:
Corr4in'stion in a dedicated inciner-
ator.
Combustion in an available plant
boiler.
Collection in a VOC recovery facil-
ity.
The best choice in a given situation will
depend on the VOC quantities, airflow
rates, plant layout, other plant equip-
ment, energy costs, and permitting re-
quirements.
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D. Rosen andM. Wool are withAcurex Corporation. Mountain View, CA 94039.
Charles H. Darvin is the EPA Project Officer (see below).
The complete report, entitled "Microprocessor Control of Rotogravure Airflows."
(Order No. PB 86-230 075/AS; Cost: $11.95. 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:
Air and Energy Engineering Research Laboratory
U.S. Environmental Protection Agency
Research Triangle Park. NC 27711
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
Official Business
Penalty for Private Use $300
EPA/600/S2-86/068
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