EPA-600/2-76-211
July 1976
Environmental Protection Technology Series
CONSTRUCTION OF A PROTOTYPE
SULFURIC ACID MIST MONITOR
Environmental Sciences Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Research Triangle Park, North Carolina 27711
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into five series. These five broad
categories were established to facilitate further development and application of
environmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The five series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
This report has been assigned to the ENVIRONMENTAL PROTECTION
TECHNOLOGY series. This series describes research performed to develop and
demonstrate instrumentation, equipment, and methodology to repair or prevent
environmental degradation from point and non-point sources of pollution. This
work provides the new or improved technology required for the control and
treatment of pollution sources to meet environmental quality standards.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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EPA-600/2-76-211
July 1976
CONSTRUCTION OF A PROTOTYPE SULFURIC ACID MIST MONITOR
by
W.S- Eaton and D.L. Strehler
Rockwel1 Internati onal
Air Monitoring Center
2421A W. Hill crest Drive
Newbury Park, California 91320
Contract No. 68-02-2220
Project Officer
James L. Cheney
Stationary Source Emission Measurement Branch
Environmental Sciences Research Laboratory
Research Triangle Park, North Carolina 27711
ENVIRONMENTAL SCIENCES RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
RESEARCH TRIANGLE PARK, NORTH CAROLINA 27711
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DISCLAIMER
This report has been reviewed by the Environmental Sciences Research
Laboratory, U.S. Environmental Protection Agency! an'dlapproved for
publication. Approval does not signify that the contents'necessarily
reflect the views and policies of the ILS. Environmental Protection'
Agency, nor does mention of trade'names or commercial'products constitute
endorsement or recommendation for "use.
n
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ABSTRACT
A prototype sulfuric acid mist monitor has been constructed for
the purpose of detecting sulfuric acid-sulfur trioxide. The monitor
utilized the selective condensation method with subsequent determination
of sulfuric acid by measuring the conductivity of an aqueous isopropanol
solution. The instrument is fully automated with a mass flow controller
and standard TTL logic to allow for easy modification of the timing
circuit. After collection of the hLSO.-SO- in the temperature controlled
spiral condenser, the sample is washed into a conductivity cell for
measurement. During conductivity measurement the condenser is rinsed
with methanol and air dried prior to the next sample collection. The
instrument was designed to measure from 1 to 100 mg/m H^SO. and presents
the measurement within a 10 mv range. The sample timing cycle can be
varied from 105 seconds to 999 seconds.
iii
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CONTENTS
Abstract ill
Figures vi
Tables vii
I. Introduction 1
II. Monitor Construction 2
A. Cabinet 2
B. Operation Description 2
C. Electrical Systems 12
D. Mechanical Systems 28
III. Testing and Calibration 37
A. Testing 37
B. Calibration 38
IV. System Documentation 45
A. Operation and Maintenance 45
V. Recommendations for Modification 46
A. Sample Probe 46
B. Cooling System 46
References 47
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FIGURES
Number Page
1. Front View 4
2. Rear View 6
3. Front View, Doors Open 8
4. Rear View, Door Open 10
5. Basic System (SAMM) 11
6. Timing Panel 14
7. Timing Circuit 15
8. Relay Panel 18
9. Relay Circuit 19
10. Distribution Panel 21
11. Distribution Circuit 22
12. Lower Electronics Compartment 24
13. Upper Electronics Compartment 27
14. Heated Compartment 30
15. Spiral Condenser Compartment 33
16. Methanol and Water Compartment 35
17. Experimental System 39
18. SAMM Calibration Curve 43
19. SAMM Calibration Curve 44
vi
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TABLES
Number Page
1. Timing Sequence 17
2. Syringe Pump Calibration Data 41
3. Calibration Values 42
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I. INTRODUCTION
The Sulfuric Acid Mist Monitor (SAMM) designed and constructed for
the Environmental Protection Agency (EPA) is described in this report.
The objective of this program was to provide one prototype acid mist
monitor for use on contact sulfuric acid manufacturing plants. The
monitor utilizes the selective condensation method with subsequent
determination of sulfuric acid by measuring the conductivity of an aqueous
isopropanol solution. Currently, only manual methods are available for
this purpose. The manual methods (EPA Standard Method 8) require exten-
sive manpower and have several problems associated with them. Among
these are losses in the probe, conversion of S02 and delays in analyzing
samples. The SAMM is capable of continuously monitoring the stack gas
3
in the range of 1 to 100 mg/m unattended. The detrimental effects of
sulfate aerosol to animals, plants, life and property has been established
(1). The specific amount of sulfuric acid emitted by stationary sources
is important in the understanding of local pollution and the mechanism
of sulfate production in an area.
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II. MONITOR CONSTRUCTION
A. CABINET
The components of the monitor are housed within an all-weather cabinet
consisting of modular compartments. Figures 1 and 2 show the front and
rear views of the cabinet, respectively. These same views, with the doors
open, are shown in Figures 3 and 4. The cabinet is of sandwich construc-
tion, with a layer of insulation between two layers of aluminum. The
sandwich was applied over an aluminum frame with a welded aluminum plate
on the bottom. All interior partitions are of the same construction.
Supports for the glassware are of aluminum angle designed to "float" in
space to protect delicate components. The final outside dimensions of the
cabinet are approximately 0.76 m x 0.63 m x 0.94 m, with a weight of about
90 Kg. The heated compartment (Figure 3-A) is thermostatically regulated
to 65°C to keep heat loss from the glassware to a minumum. Feed-throughs are
provided between compartments for gas flow, solution flows, waste liquids,
waste gas and electrical connections. Openings through the cabinet are
provided for air intake and exhaust, electrical connections for the probe
heater, recorder output and power input, the probe itself, and waste
connections for liquid and gas.
B. OPERATION DESCRIPTION
The general system as described by Richter and Sattelberg (2) is shown
in Figure 5. Basically, the system condenses sulfuric acid out of a
sample emission stack air, washes the condenser with aqueous isopropanol
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Figure 1
LEGEND:
A Heated Compartment
B Spiral Condenser Compartment
C Methanol and Water Compartment
D Exhaust Hood
-------
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4
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Figure 2
LEGEND:
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B Power Inlet Connection
C Probe Heater Connection
D Recorder Output
E Probe Holder
F Air Inlet
-------
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Figure 3
LEGEND:
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B Spiral Condenser Compartment
C Methanol and Water Compartment
-------
Fi gure 3
Front View, Doors Open
8
-------
Figure 4
LEGEND:
A Relay Panel
B Timing Panel
C Distribution Panel
D Flow Indicator
E Conductance Meter
F Isopropanol Pump
G Main Pump
H Mass Flow Controller
I Isopropanol Reservoir
J Temperature Controller
K Magnetic Stirrer Controller
-------
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10
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Figure 14
LEGEND:
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B Solenoid SV-1
C Shell Condenser
D Solenoid SV-2
E Measuring Cell
F Magnetic Stirrer
G Solenoid SV-6
H Solenoid SV-3
I Constant Temperature Bath
J Drain
K Heating Element
L Light
M Fan
29
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13
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-------
generator). These pulses are counted using a three digit BCD counter
(cycle timer). When the count reaches a predetermined limit, the BCD
counter is reset to zero and the count started over. The cycle time can
be varied from 105 to 999 seconds giving a maximum cycle time of 16.6
minutes, and a maximum sample time of 15.6 minutes. One minute 1s used
in the shell condenser washing-rinsing sequence. The various components
of the system are turned on and off using this cycle timer and a start-stop
timer. The start-stop timer consists of two 12-bit comparators which set
or reset a flip-flop when the count equals a preset value. The output is
then used to control a solid state relay which is connected to a particular
component of the system. The count for each comparator can be set to any
value over the entire counting range and is completely independent of the
other comparators, except, that the start and stop comparators for each
flip-flop cannot be set at the same value. This circuit accurately times
and controls the various components of the instrument. All component
start/stop times are preset, however, any time may be changed by removing
and replacing the wire wrap when the need arises. The preset times and
components corresponding to each relay are as follows:
16
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Table 1. Timing Sequence
Relay
Number Component Time On Time Off
1A MFC (1) Low Flow 25 90
2A MFC High Flow 1 25
2B MFC High Flow 90 End of Cycle
3 SV-8 95 105
4 SV-7 95 105
5 P3 90 107
6 SV-4 80 84
7 SV-1 34 55
8 SV-3 32 77
9 SV-2 32 77
10 SV-6 1 30
11 SV-9 1 30
12 P2 1 31
(1) MFC - Mass Flow Controller
Cycle time may be set from 105 to 999 allowing sample times from 0.75
to 15.65 minutes. The cycle time is set by placing the jumper wires on the
selected time from A, B and C shown in Figure 5 and on the cycle time
control points (Figure 7).
Relay Panel
The relay panel (Figures 8 and 9) contains on/off/auto switches for
all timed components. The timing power switch, clock actuate switch and
17
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19
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clock reset button are also on this panel. Teledyne solid state relays
are used for all timed functions. These are located in the relay panel
and connected to a terminal strip on the back of the panel. The on/off/auto
switches allow manual or automatic control of timed components. Each
component is activated when the switch is turned to "on". The "auto"
position of the switch changes control of the components to the timed
intervals set on the timing panel. During normal operation all switches
are placed in the "auto" position. The power switch is placed in the up
position to supply power (5 VDC) to the timing circuit. The clock actuate
switch is placed in the down position to start the clock running. The
clock reset button resets the clock to zero time when actuated.
Electri cal Pistribution
The electrical distribution panel (Figures 10 and 11) contains the
main power switch, switches for the main pump (PI) and heated compartment
light, fuses, controls for mass flow controller, probe and tape heaters
and plugs for components that are not controlled by the timing circuit.
Two spare 115 v AC fused electrical outlets are also provided.
Sample FlowControl
The sample flow rate is controlled by a mass flow controller (Figure
12-B, Tylan Corporation, Model No. FC-202). The flow controller incorporates
a valve and electronics to automatically regulate flow proportionally to an
external signal. The external signal is provided by the pot (Mass Flow
Controller Adjustment MFC Adj.) on the distribution panel (Figure 10).
20
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Figure 11 Distribution Circuit
-------
Figure 12
LEGEND:
A Main Pump, PI
B Mass Flow Controller
C Isopropanol Reservoir
D Temperature Controller
E Magnetic Stirrer Controller
23
-------
N
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12
Lower
Electronic Compartment
-------
The valve used in the Tylan flow controller is a thermal expansion design
that eliminates friction, moving seals and all material except 316 stainless
steel. The actuator is a small thin-wall tube with a ball welded to the end
and a cone seat. Inside the tube is a heater wire that causes the tube to
expand relative to the outer shell, moving the valve, and thereby setting
the flow. Two resistence thermometers are wound adjacent to each other on
the outside of the sensor tube. These thermometers form part of a bridge
circuit. When there is a flow in the tube, the up-stream sensor is cooled
and the down-stream sensor is heated, which produces a signal from the
bridge which is proportional to flow. The mass flow controller is set by
an external command signal from a pot on the distribution panel. The command
signal is compared internally with the amplified sensor signal to give an error
voltage proportional to the difference between the desired flow rate and the
actual mass flow rate. The control valve in the output flow path of the
controller acts in response to this signal to reduce the difference between
command and actual flow to zero. An indication of the flow is supplied on
0-5 VDC meter. One volt corresponds to 20% of full flow. The flow controller
is calibrated for air from 0-20 lit/min. The sample flow rate is adjusted by
turning the pot (MFC Adj.) on the distribution panel until the desired flow
is indicated on the meter (Figure 13-A). During the period when the
condenser is being rinsed and cleaned, the flow is automatically set at 20%
of full flow (5 lit/min), to reduce turbulence and carry over by the gas
stream.
The flow controller has fine-mesh screens permanently installed on both
the inlet and outlet section to prevent accidental clogging of the sensor
25
-------
Figure 13
LEGEND:
A Flow Meter
B Conductance Meter
C Isopropanol Pump
26
-------
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tubing or valve. An in-line filter is placed before the mass flow
controller to prevent plugging of these permanent screens and to provide
a simple, easily changed system to protect the controller. The in-line
filter contains glasswool and desiccant to prevent both particles and
moisture from carrying over. The operation and maintenance manual for
the flow controller is in the Operation and Maintenance (O&M) Manual.
Con du ctan ce Me te r
The conductance of the 5% aqueous isopropanol acid solution is measured
/
by use of a wheatstone bridge conductance meter (Figure 13-B) manufactured
by Beckman Instruments, Inc. (Model No. RA5). A visual meter indication is
provided in the electronics compartment as well as a 10 mv recorder output
(Figure 2-D) external to the cabinet. The operation and maintenance manual
for the conductance meter is in the O&M manual.
D. MECHANICAL SYSTEMS
Sampling Systems
The sampling system is comprised of a shell condenser (Figure 14-C), a
measuring vessel (Figure 14-A), and a conductance cell (Figure 14-E). Thesi
glassware components, along with the spiral condenser (Figure 14-A) were
custom made to specifications by Cal-Glass (Costa Mesa). A complete set of
drawings for the glassware is in the O&M Manual. An extra set of glassware
consisting of a measuring cell, a shell condenser, a measuring vessel and c
spiral condenser for replacement are provided with the instrument.
The components of the sampling system are double-jacketed, allowing
28
-------
SAMPUNQ
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i
T/M/A/&
CONTROL
Figure 5 Basic System (SAMM)
-------
and measures the conductance of the isopropanol-sulfuric acid solution.
To automate the procedure and obtain valid measurements, other capabilities
have been provided: temperature control, control of the sampling steps
(timing control), solution volume control, washing or cleaning of the
condenser and sample mixing. The operating sequence involves the following
steps: gas sampling, washing and drying the shell condenser, and conductivity
measurement. During the gas sampling phase stack gases are passed through
the heated quartz probe and into the shell condenser where the sulfuric acid
is selectively condensed. The condenser is washed after the end of
sampling. During the washing process the 5% aqueous isopropanol sulfuric
acid solution is introduced to the measuring cell. The condenser is then
rinsed with methanol and dried in preparation for the next sampling period.
The electrical conductivity of the isopropanol-sulfuric acid solution is
measured during the next cycle. The measuring cell is emptied before the
next washing cycle. Detailed discussions of the monitor systems are in the
following sections.
C. ELECTRICAL SYSTEMS
Timing Circuit
Standard TTL logic was used to allow easy modification, small size
and easy adaptation of the timing circuit for production at a later time.
The circuit (shown in Figures 6 and 7) has the following characteristics.
The 60 Hz line frequency (60 Hz clock pulse generator) is used as the
time base and counted to give pulses of frequency 1 Hz (1 Hz clock pulse
12
-------
thermostatic control. Temperature control is maintained by a constant
temperature Haake circulating bath. The O&M manual contains the instruction
and maintenance manual for"the temperature bath.
The measuring vessel is filled by a parastaltic pump (Figure 13-C)
operated by the timing system. The pump and reservoir (Figure 12-C) are
located in the electronics compartment. The pump is manufactured by Cole-
Parmer Instrument Co. (Model No. 7540-14).
The main sampling pump (Figure 12-A) is a dual diaphram type, manu-
factured by Gast Pump Co. (Model No. DAA 110).
The measuring cell has a number of important design features. The
cell is maintained at a constant 70°C by thermostated circulating water
(Figure 14-1). The water bath is made by Haake (Model No. £51). The cell
has a provision for a stirring bar which allows for an electronically
controlled magnetic stirrer to be placed as close as possible. A threaded
connector is provided for the conductance cell. Provision for removing the
5% aqueous isopropanol acid solution and drying with heated air is made.
The purge air pump is located in the Spiral Condenser Compartment (Figure
16-B) (Neptune Products, Inc., Model No. 54904-006).
The methanol rinse solution volume will be controlled by timing the
period in which solenoid valve SV-4 (Figure 15-D) is open. The methanol
supply container (Figure 16-B) is outside of the heated compartment
because of the low boiling point.
Because heated sulfuric acid mist is highly corrosive, the solenoid
valves in contact with the acid are Teflon (Figure 14-D & G). All of the
other solenoid valves are stainless steel.
31
-------
Figure 15
LEGEND:
A Spiral Condenser
B Purge Air Pump, P2
C Cool Water Pump, PA
D Solenoid SV-7
E Solenoid SV-9
F Solenoid SV-8
32
-------
. II.
. .
Figure 15
Spiral Condenser Compartment
33
-------
Figure 16
LEGEND:
A Cool Water Reservoir
B Methanol Reservoir
C Methanol Shelf
D Solenoid SV-4
34
-------
w
U'1
Figure 16
and Water Compartment
Methanol
-------
The spiral condenser is located outside of the heated compartment.
It is supplied with cool water (Figure 15-A) to condense methanol and
other vapors preventing damage to the mass flow controller. The cool
water pump (Figure 15-C) is manufactured by Cole-Parmer Instrument Co.
(Model No. 7540-17).
Sample Probe
The sample probe is a commercially purchased vitreous quartz lined
stack sampling probe manufactured by Research Appliance Co. (Model No.
STK-LQ-5). The probe was supplied with various interchangeable stainless
steel nozzles and a stainless steel protective covering. A pitot tube
with quick disconnect couplings was also supplied to aid in isokinetic
sampling. The commercial probe, however, was not designed to reach the
necessary temperature (300°C). This high temperature is required to keep
sulfuric acid from condensing on the probe wall and being lost from the
sample. This will require that the probe be modified (see Recommendations
for Modification section for details).
36
-------
III. TESTING AND CALIBRATION
A. TESTING
Following the construction phase, the instrument's mechanical and
electrical systems were tested. During the testing, adjustments were made
to the timing of certain functions to optimize operation. Certain problems
arose while testing which will require modification before the instrument
can be operated outside of the laboratory environment.
Testing Procedures
The heated compartment temperature control system was tested by
placing a thermometer in the center of the compartment. The control
(Figure 9-D) was set at 145 F and the system turned on. After a warm up
period, the temperature at the center of the compartment reached 145 F ± 2 F.
The primary purpose of temperature control in the heated compartment is to
reduce the temperature loss of the condensation apparatus and solution
delivery and measurement system. The constant temperature bath was tested
and calibrated with the built-in thermometer. The constant temperature bath
is used to maintain 70°C temperatures in the measuring cell, measuring vessel
and shell condenser.
The relays, timing sequence and sample flow system were tested for
v
proper operation with the specific solenoids and pumps. Solution transfer
operations for isopropanol and methanol were tested. Carryover of isoprop-
anol occurred when gas flows above 8 lit/min were used. This required that
during calibration the flow be reduced to 5 lit/min during the rinsing/
37
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washing operation. Modifications were made to automate this procedure.
In the initial testing of the gas flow system, after a period of
operation, the mass flow controller no longer properly regulated the flow.
Flow would drop to almost zero while the reading on the 0-5v DC meter
remained normal. This was traced to the spiral condenser. The cooling
water to the spiral condenser was wanning up, and consequently was not
condensing the alcohol vapors, resulting in their carry-over to the flow
controller. These vapors were condensing in the controller making it
inoperative. This problem was solved by using cool water for the spiral
condenser. No further problems were encountered with these components.
Testing of the commercial sample probe revealed that the maximum
temperature obtainable was 320°F. This temperature is not sufficient for
quantitative transfer of SO- without condensation. To complete calibration
a specially designed probe which could reach 550°F was used as the sample
probe.
Recommendations for permanent solutions to these problems are contained
in Section V., Recommendations for Modification.
B. CALIBRATION
The experimental system used for calibration is shown in Figure 17. The
special probe consists of a quartz tube heated electrically by a spiral of
nicrome wire insulated by several layers of asbestos tape. With this
arrangement, the probe temperature is adjusted with a variable transformer.
Dilute sulfuric acid solution is added at a constant rate by a calibrated
syringe pump through a hypodermic needle and serum cap in the top opening
38
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oo
. A MM.
Figure 17 Experimental System
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of the probe. The rate of acid addition was altered by adjusting the speed
of the syringe pump. Using 0.02 N H^SO, in the syringe, the pump was
calibrated at the following rates: 1.02 ml/min, 0.73 ml/min, 0.53 ml/min,
0.38 ml/min, 0.19 ml/min, and 0.073 ml/min (Table 2 shows the calibration
data). The generator ground glass fitting was connected directly to the
shell condenser in the heated compartment. This set-up simulated the
sample probe.
Calibration results are presented in two manners, micfomhos vs.
milligrams HpSO, (Figure 18) and micromhos vs. milligrams HgSO, per cubic
meter (Figure 19).
Table 3 contains experimental values as well as calculated values for
3
added mg hUSO, and concentration in mg/m . An example of the calculations
3
of the added mg HgSO^, volume sampled and concentration in mg/m are as
f ol 1 ows :
mg HSO = (ml HSO/min) x (0.98 mg/ml) x (sample time in min.)
Vol. (M ) = (Gas flow rate in lit/min) x (sample time in min.) x
10"3M /lit
cone, mg/m3 = mg H2S04/Vol (M3)
Figure 18 requires only that the total sampled volume be divided into
the milligrams H^SO, to give concentration, while Figure 19 requires that
both the sample rate and sample time be referenced to the standard of the
calibration curve (10 lit/min and 5.75 min).
40
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tABLE 2
SYRINGE PUMP CALIBRATION DATA
Pump Setting
1.1 ml/min.
0.82 ml/min.
0.58 ml/min.
0.42 ml/min.
0.21 ml/min.
0.073 ml/min.
Vol. of Flask
Time
Pump Rate
10 ml
10 ml
10 ml
10 ml
10 ml
10 ml
9;49.7
13;45.8
19;02.3
26;39.1
52;50.0
136;59.2
1.02 ml/min.
0.73 ml/min.
0.53 ml/min.
0.38 ml/min.
0.19 ml/min.
0.073 ml/min
41
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TABLE 3
CALIBRATION VALUES
Gas
Flow
Rate
Lt/Min.
10
10
10
10
10
10
10
16
16
16
10
10
10
10
10
10
10
10
10
10
10
(0.98mg/m1)
0.02N
Sample H?SO
Time Rate
Min. ml/min.
5.75
5.75
5.75
5.75
5.75
5.75
5.75
15.73
15.73
15.73
15.73
15.73
15.73
5.75 •
5.75
5.75
5.75
5.75
5.75
5.75
5.75
0.73
0.73
0.73
0.38
0.38
0.38
0.38
0.073
0.073
0.073
0.19
0.19
0.19
1.02
1.02
1.02
1.02
1.02
0.53
0.53
0.53
Conductance
Meter
Reading
pmhos
59.0
59.0
60.0
34.0
37.0
34.5
34.5
15.0
15.0
15.0
38.0
38.0
38.5
85.0
89.0
87.0
83.0
85.0
54.0
55.0
54.0
Total
rag 4
H9SO*
Added
4.1
4.1
4.1
2.1
2.1
2.1
2.1
1.1
1.1
1.1
2.9
2.9
2.9
5.7
5.7
5.9
5.7
5.7
3.0
3.0
3.0
Mean of
Meter
Readings Cone*
umhos mg/m
59.3 71.3
34.9 36.5
15.0 4.4
38.2 18.4
85.8 99.1
54.3 52.2
42
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/00
0o
C
S
o
M
H
O
S
€0
so
3.00
f. oo
7. oo
Figure 18
43
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Zo 3o 40 So
7O So 9o /oo
Fiaure 19
44
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IV. SYSTEM DOCUMENTATION
A. OPERATION AND MAINTENANCE
The operation and maintenance manual is under separate cover. This
details the steps for set-up, sampling and maintenance of the monitor.
45
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V. RECOMMENDATIONS FOR MODIFICATION
A. SAMPLE PROBE
It is recommended that the commercially purchased probe be modified
by adding new heating material and thermal insulation. Sufficient heating
material will be added to assure a temperature of at least 550°F as
measured in the air stream at the exit of the probe.
B. COOLING SYSTEM
It is recommended that the spiral condenser system be modified by
addition of a closed loop cooling system utilizing a water chiller. This
would insure a low enough temperature in the spiral condenser for methanol
condensation.
46
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REFERENCES
1. Stern, A. C., "Air Pollution, " 2nd Edition, Vol. 1, Academic
Press, N.Y.
"** i
2. Rich'ter, E. and Sattleberge, S., "Brennst-Warme-Kraft," 24, 339
(1972).
47
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-600/2-76-211
3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
CONSTRUCTION OF A PROTOTYPE SULFURIC ACID MIST MONITOR
5. REPORT DATE
July 1976
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
Eaton, W. S.
Strehler, D. L.
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Rockwell International
Air Monitoring Center
2421A West Hi 11 crest Drive
Newbury Park, CA 91320
10. PROGRAM ELEMENT NO.
1AA010
11. CONTRACT/GRANT NO."
68-02-2220
12. SPONSORING AGENCY NAME AND ADDRESS
Environmental Sciences Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
13. TYPE OF REPORT AND PERIOD COVERED
Final- 6/75,to 1/76
14. SPONSORING AGENCY CODE
EPA-ORD
15. SUPPLEMENTARY NOTES
16. ABSTRACT
A prototype sulfuric acid mist monitor has been constructed for the purpose
of detecting sulfuric acid-sulfur trioxide. The monitor utilized the selective
condensation method with subsequent determination of sulfuric acid by measuring
the conductivity of an aqueous isopropanol solution. The instrument is fully
automated with a mass flow controller and standard TTL logic to allow for easy
modification of the timing circuit. After collection of the HoSO/j-SOs in the
temperature controlled spiral condenser, the sample is washed into a conductivity
cell for measurement. During conductivity measurement the condenser is rinsed
with methanol and air dried prior to the next sample collection. The instrument
was designed to measure from 1 to 100 mg/m3 H2S04 and present the measurement
within a 10 mv range. The sample timing cycle can be varied from 105 seconds to
999 seconds.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
COSATI Field/Group
Air pollution
Sulfuric acid
Aerosols
* Sulfur trioxide
* Monitors
Prototypes
13B
07B
07D
3. DISTRIBUTION STATEMENT
RELEASE TO PUBLIC
19. SECURITY CLASS (This Report)
UNCLASSIFIED
21. NO. OF PAGES
56
20. SECURITY CLASS (Thispage)
UNCLASSIFIED
22. PRICE
EPA Form 2220-1 (9-73)
48
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