EPA-650/2-74-103
OCTOBER 1974
Environmental Protection Technology Series
DESIGN, FABRICATION, AND INSTALLATION
OF A PARTICULATE AERODYNAMIC
TEST FACILITY
ice of Reseo
Washingto
60
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EPA-650/2-74-103
DESIGN, FABRICATION, AND INSTALLATION
OF A PARTICULATE AERODYNAMIC
TEST FACILITY
by
D. D. Blann, K. A. Green, ancl L. W. Anderson
Acrotherm/Acurex Corporation
485 Clyde Avenue
Mountain View, California 94040
Contract No. 68-02-0625
ROAP No. 21ADJ-080
Program Element No. 1AB012
EPA Project Officer: D. B. Harris
Control Systems Laboratory
National Environmental Research Center
Research Triangle Park, North Carolina 27711
Prepared for
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D.C. 20460
October 1974
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This report has been reviewed by the Environmental Protection Agency
and approved for publication. Approval does not signify that the
contents necessarily reflect the views and policies of the Agency,
nor does mention of trade names or commercial products constitute
endorsement or recommendation for use.
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FOREWORD
The program described in this report was carried out for the U.S. Envi-
ronmental Protection Agency, Control Systems Laboratory, Research Triangle Park,
North Carolina, under Contract No. 68-02-0625. The contract began September
1972 and was concluded March 1973. Technical management at EPA was provided
by Jim Dorsey and Bruce Harris. The assistance of these individuals in carry-
ing out this project is gratefully acknowledged.
Dr. Larry Anderson was the Aerotherm program manager for the work re-
ported here. Project engineers were Dale Blann and Ken Green.
iii
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ABSTRACT
The trade-offs and design considerations, component selection criteria,
and final design details for a particulate aerodynamic test facility are pre-
sented. The design meets a range of performance specifications for the test
gas which include test section gas velocities to 90 ft/sec, temperatures to
450ฐF, variable humidity and gas composition, including particulates.
IV
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TABLE OF CONTENTS
Section
1 INTRODUCTION
2 FACILITY REQUIREMENTS
3 DESIGN STUDY SUMMARY 10
3.1 Open Circuit Versus Closed Circuit Tunnel 10
3.2 Horizontal Versus Vertical Test Section 10
3.3 Dust Injection Technique 12
3.4 Test Section Diameter and Length 12
3.5 Test Gas Heating 12
3.6 Air Conditioning 12
3.7 Charging the Tunnel with Combustion Products 12
3.8 Fan, Motor and Speed Control 13
3.9 Materials of Construction 13
4 MAJOR COMPONENT DESIGN CONSIDERATIONS 14
4.1 Fan and Variable Speed Drive 14
4.2 Insulation 21
4.3 Conditioning Section 23
4.3.1 Heater 25
4.3.2 Cooling Coil 27
4.3.3 Humidifier 27
4.4 Purge Section 28
4.5 Combustion Products Generator 28
4.5.1 System Selection 28
4.5.2 Hydronic Boiler 32
4.5.3 Expansion Tank 32
4.5.4 Pump 32
4.6 Dust Collector 34
4.7 Ducting, General 36
4.7.1 Conditioning Section Cross-Sectional Area 36
4.7.2 Dust Collector Entrance Elbow 36
4.7.3 Expansion Joints 36
4.8 Contraction 39
4.9 Diffuser 39
4.10 Aerosol Generator and Injection System 41
4.11 Controls and Instrumentation 43
4.11.1 Fault Lights 45
4.11.2 Velocity Control 45
4.11.3 Temperature Control 48
4.11.4 Humidity Control 49
4.11.5 Purge Section Control 52
4.11.6 Combustion Products Control 52
4.11.7 Dust Collector Control 54
REFERENCES 55
APPENDIX A - TEST FACILITY OPERATION PROCEDURE 56
APPENDIX B - Aerothern Final Test Report 74-107, TEST PHASE
OF PROJECT 7086 ENGINEERING SERVICES SUPPORT OF
PARTICULATE AERODYNAMIC TEST FACILITY 66
TECHNICAL DATA REPORT 117
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LIST OF FIGURES
Figure Page
1 Model of Particulate Aerodynamic Test Facility 3
2 Particulate Aerodynamic Test Facility for Control Systems
Laboratory, Environmental Protection Agency 4
3 Floor Space Available at North Carolina Research Facility 9
4 Schematic Diagram of Major Components of Test Facility 11
5 Plan View of Installation 15
6 Fan Characteristic Curves 20
7 Wind Tunnel Insulation Detail 24
8 Heat-up Power Required for 3-Inch Insulation 26
9 Tunnel Composition on Completion of Charging with
10 Percent Excess Air in 350ฐF CPG Exhaust 31
10 Combustion Products Generation System 33
11 Dust Collector Modular Construction 35
12 Basic Rolling Convolute Expansion Joint 37
13 Bellow Expansion Joint 38
14 Diffuser Configurations 40
15 Aerosol Generation System 42
16 Test Facility Control Console 44
17 Velocity Control System 47
18 Chiller Schematic 50
19 Humidity Control System 51
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LIST OF TABLES
Table Page
I Summary of Major Performance Specifications of
Particulate Aerodynamic Test Facility 5
II Major Equipment Description 16
III Candidate Ducting Insulation Materials 22
IV Gas Conditioning Requirements 23
V Heater Power Requirements 25
VI Boiler Models Studied 30
VII Fault Lights and Horn Alarm 46
VI1
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SECTION 1
INTRODUCTION
Aerosols emitted from stationary sources constitute one of the most com-
mon and readily observable air pollutants currently being subjected to control
measures. These aerosols, which are composed of solid and/or liquid* parti-
cles, originate in the fuel used in a typical combustion process, or in the
pre- or post-combustion process itself. Noncombustible components of coal and
oil fuels (the ash content) pass directly through the combustion zone of a
burner and are emitted to the atmosphere generally in solid form, with charac-
teristic dimensions of one-tenth to one hundred microns and larger. Sulfur and
metallic trace species in the fuel oxidize during combustion to form other aer-
osol components. Fuel-rich combustion results in many types of condensible
organics, whose state is dependent on local temperature. Dust from material
handling operations can be a problem exclusive of any combustion. Many of
these particulates are noxious, corrosive, or even toxic in large concentra-
tions. Thus, the control of aerosols is seen to be desirable not only from an
aesthetic point of view, but also from a property damage and health point of
view.
Measures currently in use for the control of particulates concentrate
both on the allowable pollutant content of the fuel (i.e., the sulfur content)
and on the allowable particulate emissions at a given installation. Particu-
late emissions for a given process are often controlled by mechanical means,
such as inertial separators, scrubbers, baghouses, and electrical precipitators.
Further advancement in the "particulate control" state of the art will require
basic information on the general behavior of particulates in flue gases. In
addition, more sophisticated and automated instrumentation to test the perfor-
mance of control equipment or compliance with air pollution regulations is
needed. Such basic information and instrumentation will play key roles in the
specification of particulate control legislation.
*
With the exception of water, which is not considered a pollutant.
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In 1971, the U.S. Environmental Protection Agency commissioned Aerotherm
Division of Acurex Corporation to perform a design study of a particulate aero-
dynamic test facility. The results of that study are contained in Reference 1.
The study describes a laboratory facility which creates a steady state test
stream whose velocity, temperature, dust concentration, and other properties
are representative of conditions in the exhaust stack of a typical "stationary
source" of air pollution, such as a utility powerplant. This laboratory facil-
ity could then be used to conduct research and development programs in the fol-
lowing areas:
Basic particulate flows
Instrumentation for stationary sources
Control device development and testing
All these R&D programs could be performed in a laboratory situation, with con-
trol over the important variables of the process.
In 1972, the Control Systems Laboratory of the Particulate and Chemical
Process Branch of the EPA commissioned Aerotherm to build this laboratory facil-
ity. At the same time, the Chemistry and Physics Laboratory of the Source
Emissions Branch of the EPA contracted for construction of a similiar facility.
Development of the two facilities proceeded in parallel and design decisions
of each were impacted to varying degrees by both configurations. A simplified
model of the final facility configuration is shown in Figure 1 and the actual
installation, prior to installation of insulation, is shown in Figure 2.
Basically, the facility is a low speed, closed loop wind tunnel. Dust
is injected just upstream of the test section and is collected in a large, cyl-
indrical-bag filter dust collector located downstream of the diffuser. The
test section is a modular, 24-inch diameter duct, 40-feet in length. The en-
tire system is insulated for high temperature operation. Table I summarizes
some of the facility capabilities.
This final report on the particulate aerodynamic test facility is in-
tended to supplement the Reference 1 study, providing information on the final
as-built configuration and some of the reasons for design decisions. Section 2
presents the design requirements, Section 3 is a review of the conclusions of
the Reference 1 study, and Section 4 discusses some of the considerations for
each of the major components. Appendix A describes step-by-step facility opera-
tion. Complete facility operation instructions are contained in the Operations
and Safety Manual, Reference 2.
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u>
Figure 1. Model of Participate Aerodynamic Test Facility
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Figure 2. Particulate Aerodynamic Test Facility for Control Systems
Laboratory, Environmental Protection Agency
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TABLE I
SUMMARY OF MAJOR PERFORMANCE SPECIFICATIONS
OF PARTICIPATE AERODYNAMIC TEST FACILITY
Test Section
Dimensions
Velocity
24" Diameter
40' Long (four 10-foot test section
modules)
0-90 fps
Gas Conditioning Capability
Temperature
Moisture Content
Composition
Ambient to 450ฐF
Humidifier capable of supplying 50 Ib/hr
dry steam
0 to 100 percent combustion products from
gas fired boiler; other constituents by
separate injection
Particulates
0-10 gr/ft3 fly ash, depending on test
section velocity
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SECTION 2
FACILITY REQUIREMENTS
The basic design requirements for the particulate aerodynamic text fa-
cility were established in the design study conducted for the EPA by the Aero-
therm Division of Acurex Corporation (Reference 1). Following is a summary of
the requirements defined by the study including those areas where the design
study-generated requirements were modified in the actual design.
Conditioned Air Test Stream
The facility will operate with air as a test gas. The original require-
ment stated that the air temperature in the test section would be 70ฐF - 100ฐF
with a 10-80 percent relative humidity level. Precision control of the tem-
perature and humidity level at any intermediate setting will be provided. These
test conditions will be attainable on a 24rhours-per-day, 365-days-per-year
basis using the ASHRAE 99 percent climate criteria for Durham, North Carolina.
As designed, the test facility will operate with air at any temperature
setting in the range 70ฐF - 450ฐF in the test section.
A consideration was given in the design study to the achievement of 10
percent R.H. at room temperature. Cost consideration strongly favored a chil-
led water cooling coil, which relies on the central chilled water supply avail-
able in the EPA research facility Wing G. Since the chilled water supply tem-
perature may be as high as 45ฐF, the lowest dew point achievable in the test
stream is approximately 50ฐF, which corresponds to R.H. values ranging from
18 percent at 100ฐF to 50 percent at 70ฐF air temperature. These values must
be considered the low humidity design points.
The requirement for operation at elevated humidity in the range 70ฐF -
100ฐF was relaxed during the design and development effort and emphasis was
placed by the EPA technical monitor on achievement of typical combustion pro-
ducts humidity levels with or without exhaust gases. The primary design goal
that evolved for the upper limit humidity requirement is a dew point temperature
of 125ฐF - 130ฐF, achievable at typical exhaust gas dry bulb temperatures (in
excess of 200ฐF).
Operation at high humidity at 70ฐF - 100ฐF, a situation in which the bag-
house may be at dew point or below with resultant condensation on the filters,
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is an undesirable condition because of possible "blinding" of the filter bags.
Therefore such operation, although attainable, requires extreme caution.
Exhaust Gas Test Stream
The facility will also generate and operate with typical power plant
combustion products as a test stream. The exhaust products temperature in the
test section will be 170ฐF to 450ฐF, with precision control of the gas tempera-
ture and composition provided. Exhaust products will be generated with natural
gas fuel.
Particulate Loading
The conditioned air or exhaust products test stream will be loaded with
0.1-5.0 grains/ft3 of solid particulate material. The particulate material
will range from 0.2-20 microns mean diameter, and will be uniformly mixed in
the test gas at a known axial station in the test section.
Test Section
The test stream will flow through an enclosed test section of round
cross-section, with a two-foot maximum internal diameter. The test section
construction will allow interchangeable duct sections typical of fossil fuel
combustion system breechings to be installed at several locations as an inte-
gral part of the test section. Test section length and minimum diameter will
be determined as part of the design effort. The facility design should be such
that a "low" free stream turbulence level will be encountered in the test sec-
tion. Observation and lighting windows will be an integral part of the test
section construction, with window material of suitable quality for transmissom-
eter or photographic data-taking. The flow velocity in the test section will
be 5-90 ft/sec with precision control to any intermediate velocity setting.
Hot and Cold Operation
The facility will be capable of running in either the hot flow or cold
flow mode, with a reasonably convenient method of changing from one mode to the
other. The changeover need not be performed while the facility is in operation.
Exhaust Streams
Any gaseous exhaust streams from this test facility must meet local,
state, federal, and EPA air pollution and safety regulations.
Controls
A single control station will be provided for the operation of this fa-
cility. Instrumentation will include all diagnostic and safety equipment typi-
cal of a combustion facility of this size.
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Facility Cleanout
Means for accomplishing a rapid cleanout betwen tests of all flow sur-
faces exposed to the particulate material will be provided.
Miscellaneous Requirements
In addition to the operational specifications listed above, a few other
requirements less obvious do have to be considered. The most important of
these is the space allotment for facility installation in Wing G of the EPA
research center. Figure 3 shows the floor space available for this facility.
Ceiling height is nominally 20 feet, with numerous air conditioning and utility
ducts hanging from the ceiling.
Another requirement is the insulation of nearly all tunnel components
for safety reasons. With a test stream temperature of 450ฐ, the possibility of
burns and high heat load to the laboratory requires that insulation be instal-
led.
Noise and vibration from the fan must be considered. The large capac-
ity fan required to move greater than 17,000 scfm of air or test gas may re-
sult in very high noise levels in the vicinity of the fan, and is a potential
source of vibration for the supporting structure if adequate measures are not
taken to eliminate them.
Finally, ready and reasonably convenient access should be provided to
the test section for rapid modification of probe or model set-ups.
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7.0
vo
n
14-0"
Figure 3. Floor Space Available at
North Carolina Research Facility
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SECTION 3
DESIGN STUDY SUMMARY
The design study (Reference 1) considered engineering trade-offs for
the major components in the particulate aerodynamic test facility, thus laying
the ground work for component selection in the development and fabrication
effort. As background information for this final report, a brief summary fol-
lows of the design recommendations that were made in the design study.
3.1 OPEN CIRCUIT VERSUS CLOSED CIRCUIT TUNNEL
The design study concluded that the test gas circuit should be closed
loop and the particulate circuit should be open loop. Open loop operation
with exhaust gases would consume a large amount of fuel (300-400 gallons/hour
of fuel oil at 90 ft/sec test section velocity) and require a large heat ex-
changer system to cool the exhaust gases to tunnel operating temperature.
Similarly, open loop operation in cold flow would require a large air condi-
tioning unit. In addition, experience in other facilities has shown that a
closed circuit tunnel results in better control over the test stream and less
noise.
The particulate circuit should be open loop because in the closed loop
design the particle loading becomes degraded with time by agglomeration, wall
deposition and particle fracture. In addition, fan blades may become coated
and eroded, degrading performance.
Figure 4 is a schematic of the closed-loop particulate wind tunnel,
showing the relative orientation of major components. Particles are injected
ahead of the test section and collected downstream of the diffuser.
3.2 HORIZONTAL VERSUS VERTICAL TEST SECTION
The design study concluded that on the basis of cost, convenience, and
flexibility a horizontal test section is the most practical. A brief techni-
cal analysis showed that technical objectives would not be seriously compro-
mised for the particle size range of interests.
10
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APPITIVE3
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3.3 DUST INJECTION TECHNIQUE
The study recommended that the most cost effective dust feed system
that would satisfy specifications is a vibrating hopper dust supply feeding
dust to an air aspirator. Dust metering would be done with either variable
orifice valve or a screw conveyor. The resulting aerosol would be injected
isokinetically into the tunnel through multiple nozzles in the tunnel settling
chamber.
3.4 TEST SECTION DIAMETER AND LENGTH
In determining the test section size, consideration was given to wall
boundary layer thicknesses, test model sizes, probable dust mixing length, and
flow entrance and exit transition lengths. A 2-foot diameter 40-foot long
test section was determined optimum.
3.5 TEST GAS HEATING
An electric resistance duct heater was recommended on the basis of
control accuracy, cost, and availability.
3.6 AIR CONDITIONING
As indicated in Section 2 on facility requirements, a chilled water
coil was recommended in the design study to provide dehumidification capa-
bility. It was noted that the minimum humidity requirement as originally
specified by EPA could not be achieved with this approach. However, the al-
ternate design of a direct expansion refrigerator containing ammonia or freon
would offer a small improvement in relative humidity limits and would be quite
expensive.
3.7 CHARGING THE TUNNEL WITH COMBUSTION PRODUCTS
In a closed loop system, the enclosed volume may be precharged with a
test gas consisting of combustion products (primarily N_, CO., and H^O) in the
proper proportions. The precharged tunnel is then ready for testing. The
design study concluded that a small burner should be used to supply the com-
bustion products. Cooling the gases from combustion chamber temperature to
wind tunnel operating temperature was considered a difficult problem and the
tentative conclusion was to dilute with tunnel gas prior to injection into
the tunnel.
12
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3.8 FAN, MOTOR AND SPEED CONTROL
The presence of particulate natter downstream of the test section dic-
tates that the fan should be upstream of the test section. The large flow
resistance of the baghouse requires that the fan should be a centrifugal
blower to overcome the pressure drop. An airfoil blade design minimizes the
noise and pulsating flow characteristic of radial-blade centrifugal blowers.
The obvious choice for the drive was an electric motor. Speed control
by means of an eddy current coupling to a constant speed AC motor was rec-
ommended from the various alternates on the basis of range, low cost, and
simplicity.
3.9 MATERIALS OF CONSTRUCTION
Recommended tunnel material was steel, based primarily on the 450ฐF
operating requirement. Depending on the criticality of the application,
stainless steel, bare mild steel, and coated mild steel were recommended in
the study in various sections of the tunnel.
13
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SECTION 4
MAJOR COMPONENT DESIGN CONSIDERATIONS
The particulate Aerodynamic Test Facility, as built, met or exceeded all
the design requirements presented in Section 2. As would reasonablly be ex-
pected, however, in a project of this magnitude, the detailed design and fabri-
cation phases did produce some variances between the actual facility as built
and what was presented in the original design study. The differences were not
so much in principle as in detail.
Most of these variances can be attributed to a closer evaluation of the
economics of the situation, while others resulted simply from engineering con-
siderations unforeseen or ignored for simplicity in the original design study.
This section, which is the main body of this report, will deal with the specifics
of these variances and discuss the considerations that entered into the design
and/or specification of the wind tunnel components.
Figure 5 is a plan view of the Particulate Aerodynamic Test Facility
with major components labeled. Table II summarizes the tunnel component selec-
tion including a brief description of each of the major components and the
supplier.
4.1 FAN AND VARIABLE SPEED DRIVE
As noted in Section 3, the design study had concluded, after rather
detailed engineering trade-off study, that a centrifugal type fan was an optimum
choice over other types for the wind tunnel facility. Specifically, an airfoil
blade centrifugal was recommended for its higher pressure rise, wider speed
range with good flow quality, and low swirl component at the fan exit.
The fan and drive selection followed this procedure:
1. Fan static pressure requirements were determined using preliminary
tunnel layouts and duct dimensions.
2. Fan characteristic curves were cross-plotted with tunnel character-
istic curves for a number of fan sizes. Horsepower and efficiency
were calculated.
3. Preliminary size selection was made and bids solicited from several
manufacturers.
14
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Figure 5. Plan View of Installation
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TABLE II
MAJOR EQUIPMENT DESCRIPTION
Item
1
2
3
4
5
6
7
8
9
Qty.
1
1
1
2
3
1
1
1
1
Description
Airfoil blade, centrifugal blower, 30-inch tip diameter, insulated
housing, 304 stainless steel construction on all gas stream surfaces,
flanged inlet and outlet, access door, V-belt drive, belt guard.
Operating conditions:
22.200 cfm @ 10.6" W.G. AP 2100 rpm @ 70ฐF
22.200 cfm @ 6.2" W.G. AP 2100 rpm @ 450ฐF.
Constant speed, squirrel cage motor, 480 vac 3$, integral with eddy
current clutch. Horizontal foot mountings, blower cooled, continuous
duty. Solid state single channel speed controller with ac tachometer
in separate wall-mounted enclosure (WER Industrial Corp.)
Motor rating: 50 hp @ 1800 rpm
48" x 48" opposed blade damper, vertically oriented, 304 stainless
steel on all gas stream surfaces.
Butterfly valves, 12" inside diameter, 304 stainless steel, flanged.
Electric actuators, Model 1026, for items 3 and 4
Duct heater, 200 kw, 480 v 3 480 v SCR power controller, one
adjustable-band proportional controller driver unit with set point
adjustment, one set point controller unit with manual reset, two heater
overtemperature controllers.
Chilled water cooling coil, 48" x 48" frontal area, finned tubes, drain-
able, flanged, condensate collection pan with loop seal drain, 304 stain-
less steel construction on all gas stream surfaces.
Steam humidifier, air operated, modulating with operator, steam jacketed
manifold, steam trap, temperature switch, stainless steel construction
on all gas stream surfaces.
Supplier
Garden City Fan and Blower Co.
Miles, Michigan
U.S. Electrical Motors
Burlingame, California
American Warming & Ventilating
Inc. ,
Toledo, Ohio
Same as item 3
Leeds & Northrop Company
North Wales, PA
Pacific Chroma 1 ox Division
Emerson Electric Co.
Col ton, California
Same as item 6
Rempe Company
Chicago, Illinois
Armstrong Machine Works
Three Rivers, Michigan
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TABLE II (Continued)
Item
10
11
12
13
14
15
16
17
18
19
Qty.
1
1
1
1
1
1
1
1
1
1
Description
Dry Materials Volumetric Feeder, 2-1/2 ft3 vibrating hopper,
screw feeder, 10:1 variable speed transmission, 4 screw sizes
(GFE systems, which will be superseded by 2nd generation aerosol
generator, in development)
Bag filter system, 2088 ft2 minimum filter area, enclosed in-
sulated housing, screw conveyor and drive, compressed air
manifold with valves and timer, venturi throats, Nomex filter
bags, removable internal grating, hatch access to clean and
dirty air plenums, 300 series stainless steel on all gas stream
surfaces except in specified locations.
Hot water boiler, 30 Ib, 20 hp, Progress model, four-pass
horizontal five-tube, forced draft natural gas burner, FIA-
approved burner controls.
Heat exchanger, pump, and expansion tank for hot water system
for item 12.
Combustion products di verier valve set (two 6- inch valves)
Pneumatic actuator for item 14
Boiler draft modulator valve (one 6-inch valve)
Electric actuator for item 16
Wind tunnel ductwork, all sections, 304 stainless steel on all
gas stream surfaces, flanged
Ductwork support carriages and support towers, boxbeam
construction, primed and painted.
Supplier
Acrison Inc.
Carlstadt, N.J.
Miller Industrials
Division
Industrial Clean Air
Berkeley, California
Cleaver Brooks Company
Milwaukee, Wisconsin
Bell and Gossett
Fluid Handling Div. of
ITT
Morton Grove, Illinois
W. C. Morris Division
Dover Corporation
Tulsa, Okla.
Contromatics Corporation
Division of Litton Ind.
Rock vi lie, Conn.
Same as item 14
Ramcon Actuators and
Controls
Hills-McConna
Carpentersville, 111.
A. R. Peterson and Sons
Hayward, California
Master Metals
San Jose, California
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TABLE II (Concluded)
Item
20
21
22
Qty.
1
1
1
Description
Exhaust 12-inch diameter ducting and combustion
products 6- inch diameter ducting, flanged
Tunnel insulation, 3-inch thick; fiberglass and mineral fiber
blankets, secured with weld pins and galv. wire, finished with
galv. poultry wire and 1/4 inch cement, 8-oz canvas sized,
service temp = 650ฐF
Control console, relays, switches, meters
Supplier
Comfort Engineering
Durham, N.C.
Matls:
Owens Corning Fiberglas
Corporation
Toledo, Ohio
Forty-Eight Insulations,
Inc.
Aurora, Illinois
Installation:
Piedmont Insulation
Durham, North Carolina
Equipment: Various
Assembly:
Aerotherm Division
Acurex Corporation
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4. Design calculations were updated to final tunnel configuration
requirements as the design progressed.
5. Final fan selection was made on factors of cost, delivery schedule,
efficiency, noise, desired margin of safety, and compatibility with
the potential drive systems.
Fans of this type may be slightly oversize or undersize and still meet
delivery requirements. Thus, the 27-inch and 30-inch wheel diameter range
could be shown to meet the tunnel delivery requirements.
Figure 6 presents the results of the fan characteristic analysis for
the wind tunnel and the chosen vendor's fans. The preliminary analysis was
based on a gas conditioning section of 6 ft x 6 ft cross section, with a 1-
inch W.G. pressure drop. Calculations showed fan requirements to be approxi-
mately 7.4 inches W.G. (Point A, Figure 6). Based on these requirements, two
fan sizes were appropriate, depending on horsepower available. Figure 6 shows
that all fan/drive combinations would provide suitable margin.
The conditioning section design was subsequently modified to 4 ft x 4 ft,
increasing velocity and pressure drop at that location. The new fan require-
ment appears as Point C in Figure 6, resulting in the elimination of the
40-horsepower drive option. The figure shows that the 40-horsepower drive pro-
vides only a 10-percent margin over the nominally calculated fan requirement
at the calculated design point. Since the degree of conservatism in the anal-
ysis is not well defined, a 10-percent margin is inadequate. In addition, the
30-inch diameter fan offers the following advantages:
1. Lower rpm for a given fan requirement resulting in quieter and
smoother operation
2. Slightly higher efficiency
3. A small price increase over the 27-inch diameter size
Consequently the 30-inch diameter, 50-horsepower fan was selected.
The original design study established the basic trade-off factors be-
tween types of variable-speed drives and the choice narrowed, for purpose of
the actual design selection, to either SCR/dc or SCR eddy current clutch type
drives. Since these drives were comparable from a systems standpoint, the
final criteria was one of price. The choice was straightforward as the eddy-
current coupling device with a constant speed ac motor proved to be about 20
percent less expensive.
19
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20
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4.2 INSULATION
The external insulation performs three basic functions:
1. Reduces heat leaks from the tunnel at elevated temperatures,
2. Reduces the possibility of condensation on cold surfaces at high
humidity levels, and
3. Protects facility personnel.
The basic choices when designing an insulation system involve optimizing per-
formance (usually a function of thickness for a given material) vs. costs.
Actual material costs for insulation are relatively small compared to
installation costs. Therefore, reasonable variations in insulation thickness
do not appreciably perturb the total price of an insulation system within
practical installation limits. However, such thickness variations do impact
heating and cooling requirements with a resulting effect on the cost of these
components.
The duct insulation must have a service temperature of 450ฐF at most
locations and 500ฐF - 650ฐF in the region of the heater. Installed and fin-
ished, it must withstand occasional light impact and must have a clean, smooth
appearance on both square and round ducting. The thermal conductivity must be
as low as possible over the range of average operating temperatures. If possi-
ble, it should not contain asbestos. Cost and availability are also considera-
tions.
Table III presents the major types of insulation considered. The selec-
tion narrowed to glass fiber or universal fiber blanket or both on the basis
of service temperature, ease of handling (low density) and cost. Quotations
were obtained from various insulation installers. The final selection was
influenced by availability of material. The square ducting was insulated with
mineral fiber batt and the round ducting was insulated with the less dense and
more flexible glass fiber blanket.
The size of heater required to hold steady state conditions at the peak
operating condition of 450ฐF depends on the insulation thickness. However, as
will be discussed in the subsections on heaters, roughly 60 percent of the total
heater capacity is governed by the tunnel heat-up requirement. So in this design,
insulation thickness does not have great leverage on heater cost. Considering
all factors, including heater requirements, heat load to the laboratory, insula-
tion surface temperature, gas temperature decay between test section inlet and
outlet, and insulation availability, an insulation thickness of 3 inches was
selected.
21
-------
TABLE III
CANDIDATE DUCTING INSULATION MATERIALS
Insulation
Material
Glass fiber, bonded with
thermosetting binders
(without facing)
Mineral fibers, with
various binders
(without facing)
Polyurethane Foam
Calcium Silicate
Reinforced with small
amounts of asbestos
Form
Blanket or
batt
Batt
Board or
foam in place
Block
Density
(lb/ft3)
3-6
4-8
1.5-2.5
10-13
Service
Temperature
(ฐF)
450-1000
depending on type
650
250
1200
Thermal
Conductivity
(ฐF) (Btu/hr-ft3F)
100 .020*
200 .025
300 .032
400 .040
100 .020
200 .022
300 .027
100 .013
200 .016
100 .028
200 .031
300 .034
400 .038
Typical
Manufacturers
Owens-Corning
Johns-Man vllle
Forty-Eight
Insulations, Inc.
Owens-Corning
Data is for Owens Corning Intermediate Service Board and is typical of the glass fiber insulations.
-------
Allowing for heat leaks at flanges and other penetrations, the effective
normal conductivity for the insulation system can be taken as 0.04 Btu/hr-ft-ฐF.
The total heat leak from a 450ฐF internal gas temperature condition is calcula-
ted to be approximately 54 Btu/hr-ft2. Assuming 3000 ft2 of tunnel surface,
the incremental load on the laboratory air conditioning is 14 tons, the insula-
tion surface exposed to personnel will run at 105ฐF maximum. Exposed metal
surfaces will run hotter, of course. The worst case gas temperature decay be-
tween test section entrance and exit will be 10ฐ - 15ฐ, occurring at the hottest
condition and minimum flow rate.
The insulation system was installed as shown in Figure 7. A 2-inch-plus-
1-inch layup provides easier application over stiffness than a grooved 3-inch
blanket. On flat surfaces, the insulation was impaled on welded pins. On
cylindrical sections, wire bands were used in place of the pins. A covering
of 18 gauge galvanized poultry wire was finished with insulating cement (1/4
inch thick) and covered with 8 oz canvas sized with lagging adhesive.
At bolted flanges, expansion joints, and test section windows, the in-
sulation was beveled at an angle of approximately 45ฐ for access to the bolts.
4.3
CONDITIONING SECTION
The conditioning section consists of a chilled water cooling coil, an
electric heater and a steam humidifier. Its purpose is to achieve, in the test
section, an operating set point within the ranges listed in Table IV for closed
loop flow rates of 940-17,000 cfm.
TABLE IV
GAS CONDITIONING REQUIREMENTS
Condition
Set Point Range
Gas Temperature
Humidity
70ฐF - 450ฐF
"Typical" Stack Exhaust Product
Moisture Content:
Up to 14% - 15%
Moisture By Volume
70ฐ
to
100ฐ
Min: 0.008 Ib H-0 per
Ib air
Max: > 55% R.H. depend-
ing on velocity
and temperature
23
-------
STIFFENED {TYP)
TUNNEL
PIN
SPEED MOT
(TYP}
(INSULATION
Figure 7. Wind Tunnel Insulation Detail
24
-------
4.3.1 Heater
Based on the insulation effective thermal conductivity presented in 4.2,
the system steady state heat leaks were computed at maximum temperature and
maximum and minimum flow rates. The results were increased by 50 percent to
allow adequate margin for uncertainty. Table III summarizes the resulting
steady state heater power requirements. Blower power dissipation is considered
negligible because, on the conservative side, it is less than 10 percent of the
heater power required.
Heat-up power was sized on the assumption of a duct system weight of
25,000 pounds with a specific heat of 0.12 Btu/lb-ฐF and the insulation design
of 4.2. On that basis, heat-up histories are presented in Figure 8 for various
power inputs. It was concluded that the design study estimate of 200 kw of
heating power was still valid, resulting in a maximum heat-up time of 2 to 3
hours when uncertainties are included. Thus, an elevated temperature test
run could be easily initiated and completed in a single working day without
designing timer-initiated start-up into the controls. Table V includes the
heat-up power requirement for both tunnels.
TABLE V
HEATER POWER REQUIREMENTS
Steady State Power Required to
Achieve Maximum Temperature (kw)
@ Minimum Flow (kw) 60
@ Maximum Flow (kw) 75
Start-up Power for Elevated
Temperature Operation (kw) 200
The heater selected consists of 90 incoloy-sheathed hairpin resistance
elements, suspended from a flanged terminal box. The heater power supply is
480 VAC-3<|>-60 Hz. Two runs of heater elements are used only in heat-up and are
wired in identical circuits of 62.5 kw each. Two rows are wired for 75 kw
for steady state operation. Peak watt density on the heat-up elements is 24
watts/in2, while the peak density on the steady state elements is 13 watts/
in2. Including the effect of radiation heat transfer to the duct walls, which
is the dominant mode at low flow (1 ft/sec), the element surface temperatures
should remain below 1000ฐF, which is roughly 500ฐF below maximum allowable.
25
-------
Figure 8. Heat-up Power Required for 3-Inch Insulation
26
-------
4.3.2 Cooling Coil
The cooling coil is required to perform two main functions:
1. Remove blower power dissipation to maintain the ambient condition
in the tunnel, and
2. Dehumidify the gas to meet specific humidity requirements.
The governing factor in the design of the chiller was the requirement
to absorb blower power. If this was not done, the tunnel could achieve a
steady state operation temperature approaching 200ฐF at maximum flow rate and
horsepower input, just from the blower dissipation alone. Accordingly, the
coil was designed to remove 50 hp from the gas at 70ฐF. It can be shown that
dehumidification to a dew point of approximately 50ฐF can be achieved in a
short start cycle with a cooling coil sized to remove fan power.
An optimization study of the coil based on gas pressure-drop limits and
cost, in conjunction with vendor-recommended gas velocity across the coil,
dictated a finned coil arrangement of roughly 16 square feet of face area. The
coil is basically a counter-flow heat exchanger composed of straight plate
vertical fins on horizontal tubes spaced on 1.5 inch centers in staggered rows.
Condensed moisture flows down the fins to a drip pan and out a loop seal to a
drain.
The Aerotherm analysis of coil size agreed within 25 percent of the
analysis made by the prime vendor. (The Aerotherm design came out smaller.)
To provide plenty of margin, the vendor enlarged his recommended size by 40
percent, resulting in a coil with four tube rows. For a 10ฐF water temperature
rise the water flow rate must be 25 gpm to remove 50 hp. Under humid conditions,
the latent heat removal will require greater water capacity, but this is not
expected to exceed 75 gpm. Conversely, the temperature rise allowed may be
greater than 10ฐF.
4.3.3 Humidifier
The basic design requirement that moisture content be typical of industry
stack exhaust products implies that the tunnel dew point be in the range of
125ฐF - 130ฐF. For protection against condensation, an upper limit was set at
150ฐF. Actual total moisture requirements depends on gas temperature; but
assuming 300ฐF as representative and a charging time of 20 minutes, the humidi-
fier capacity required was calculated to be 66 Ib/hr. Higher humidity levels
at elevated temperatures could be achieved by extending the charging period.
27
-------
The humidity level achievable in the ambient range of 70ฐF - 100ฐF will
depend specifically on the temperature and velocity through the cooling coil
which continuously removes moisture. The maximum attainable steady state rela-
tive humidity at a worse case condition in which maximum moisture removal oc-
curs in the cooling coil will be approximately 55 percent. At lower tempera-
ture and higher and lower velocities, a greater R.H. can be achieved.
The humidifier consists of a manually-controlled pneumatically-activated
dry steam injector, which utilizes 10 psi facility steam.
4.4 PURGE SECTION
The primary purpose of the tunnel purge section is to purge the system
of test gases at the completion of a test run. In addition, the combustion
products generator is ducted into the tunnel at the purge section.
The purge section consists of three valves located downstream of the
blower. The valves include the 4 ft x 4 ft tunnel vane damper, the 12 inch
diameter butterfly exhaust valve and the 12 inch butterfly inlet valve. The
inlet valve draws laboratory conditioned air from the tunnel ambient environ-
ment. The exhaust valve couples the tunnel to an exhaust stack which extends
through the roof above the building.
In the purge mode, gas is circulated around the tunnel loop, the duct
damper is closed, and the inlet and exhaust valves are opened, effectively
exhausting test gas outside the building and replacing it with fresh air from
the room. During normal testing operation, the inlet valve is kept tightly
closed, the duct damper is open and the exhaust valve is open to establish a
pressure datum within the tunnel.
4.5 COMBUSTION PRODUCTS GENERATOR
4.5.1 System Selection
One of the few major differences between the design study conclusions
and the actual as-built Particulate Aerodynamic Test Facility was in the area
of combustion products generation.
The purpose of the combustion products generator (CPG) is to produce a
tunnel gas constituency typical of a power plant. It was concluded in the
design study that an external custom burner system would be the most effective
technique for displacing tunnel air with combustion products, and presented
a preliminary sketch of what such a burner might look like.
28
-------
During the actual design phase, however, a thorough reevaluation of the
various options discussed in the design study showed that a packaged boiler
system would be both economically and performance competitive with a custom
burner design, primarily because it was shown that design requirements could
be met with an energy release system significantly lower than the 2,000,000
Btu/hr originally thought necessary.
Consequently the evaluation focused again on the following five alter-
natives, but only in the 500,000 Btu/hr range:
1. Firebox with dilution and gas-to-air heat exchanger
2. Firebox with dilution and gas-to-water heat exchanger
3. Hydronic boiler with water-to-water heat exchanger
4. Steam boiler with steam-to-water heat exchanger (closed loop)
5. Steam boiler with water softening system (open loop)
Considerations of cost, compactness of equipment, ease of installation,
and ready availability of large quantities of chilled water narrowed the choices
to 3 and 4. Table VI shows the various boiler designs and manufacturers in-
vestigated.
Natural draft boilers were eliminated from contention because excess
air is high (40 percent) under normal operation and may become higher if an
induced draft fan is included in the exhaust ducting. Modification of dampers
in the natural draft boiler is possible to reduce excess air, but is risky be-
cause the outcome is presently not predictable.
Capacity requirements were analyzed from a tunnel leakage standpoint.
Figure 9 shows how leakage affects final tunnel composition after completion
of charging. The 20 hp boiler is a standard size and provided a significantly
greater margin for leakage than the 10 hp boiler. The 30 hp boiler does not
appear to make a major additional contribution. It was concluded then, that
20 hp was an optimum choice.
Final pricing of acceptable units showed a 20 percent variance; Cleaver-
Brooks was lowest, and in addition uniquely included in its price prepaid
shipping and services of a local service engineer to start, adjust, and test
the boiler. The price trade-off between steam and hydronic was negligible.
Since hydronic is safer because of the great expansion capability of steam, a
water boiler was favored.
29
-------
TABLE VI
BOILER MODELS STUDIED
Manufacturer
Eclipse
Ray pa k
Teledyne Laars
Fulton
Cleaver-Brooks
Boiler*
HP
20
20
20
12
13
10
20
20
Configuration
Fire Tube
/
/
/
Water Tube
/
/
/
/
/
End Product
Steam
/
Water
/
/
/
/
/
/
/
Draft
Natural
/
/
Forced
/
/
/
/
/
/
*1 boiler hp = 33,475 Btu/hr.
-------
u
X
0
A IE
\OO "2OO
1K1TO TUNNEL>
Figure 9. Tunnel Composition on Completion of Charging with
10 Percent Excess Air in 350ฐF CPG Exhaust
31
-------
The Cleaver-Brooks system was selected on the basis of price, quality
of exhaust products, relative simplicity of the system, and a good understanding
of the problem by their personnel.
The combustion products system includes the hydronic boiler, an expan-
sion tank, a recirculation pump, a heat exchanger, and various damper valves.
Figure 10 is a schematic diagram of the system. The components are described
in more detail below.
4.5.2 Hydronic Boiler
The boiler is a Cleaver-Brooks Progress Model 20 hp firetube boiler
supplying hot water at 200ฐF and 20 psi. The boiler is a four-pass horizontal
firetube boiler with 100 square feet of heating surface. The boiler is complete
with integral forced draft burner, FIA burner safety controls, boiler trim and
refractory. The boiler operates on natural gas. The gas pilot is the premix
type with automatic electric ignition. The FIA-type gas train provides extra
safety controls over the standard gas train. Water leaves the boiler at 200ฐF
and the unit is equipped with a high limit water temperature cutout set at
240ฐF. Water is returned to the boiler at 1"70ฐF from the heat exchanger.
Initial adjustment of the boiler firing rate and the heat exchanger hot and
cold side flow rates will establish the optimum operating conditions in future
runs.
Exhaust products exiting from the boiler at 300ฐF to 400ฐF are fed
either to the tunnel exhaust stack or to the tunnel through a draft damper
and diverter valve via a 6 inch duct (refer to Figure 10). The exhaust line
joins the tunnel exhaust line above the tunnel exhaust damper. The combustion
products generator fill line enters the tunnel fill line below the tunnel in-
let valve (valve 4). Interlocks and control of the system will be discussed in
Section 4.11.6.
4.5.3 Expansion Tank
Immediately above the boiler and connected to the feed water piping is
a 15 gallon expansion tank to allow for heat-up of the system. Make-up water
is automatically fed to the system if any loss of water occurs.
4.5.4 Pump
An in-line pump powered by a 1/2 hp, I*, 120 V motor circulates water
through the boiler and a hot water-to-chiller water heat exchanger.
32
-------
u>
Ul
SIGHT.
<* LASS
EXHKUST
EXPANSION
TANK
SERVICE
WATER
-cx
x\/\
NO NO
&XHAl>ST
(CONSOLED P
TUNNEL
COMBUSTIBLE
MIXTURE
NO MOP M ALLY OPEN
NC NORMALLY
PReS&URe REGULATOR. VALVE
CHECปC VALVE
\) THERMOCOUPLE (METER CM CONSOLE
/ PAMPER VALVES;
PEAFT
PlVERTgR, eXHAUST \
PIVERTSR, TUNNEL /
IKJLET
THERMOSTAT
HYPROMlC.
BOILER
7_
uo
CHILLED
OPPOSSD ACTION
opposep BLAPC
PAMPER
Figure 10. Combustion Products Generation System
-------
4.6 DUST COLLECTOR
The bag-type, pulse-clean dust collector selected for the wind tunnel
facility to filter the particulate from the gas was not significantly different
from that recommended in original design study. However, the actual specifi-
cation and dust collection procurement was not a straightforward process.
First of all, the potentially corrosive environment necessitated that
the dust collector, like the ducting, be fabricated of stainless steel or be
coated with acid resistant high temperature paints or an enameling process.
Such coatings were investigated, but fabrication costs with coatings proved to
more than outweigh any savings in basic structural material cost over all
stainless steel construction. Coatings would have also required periodic and
costly maintenance.
Secondly, and perhaps most important, envelope considerations virtually
eliminated any standard design of the right capacity on the market. Height
restrictions were severe and necessitated a shallow angle hopper; length re-
strictions virtually dictated an upper limit on number of bags and thus limited
filter area to 2080 ft2.
In addition, other considerations such as existing building penetrations
(high bay door) required a custom combination modular/knock-down construction
to allow the dust collector to be assembled in place. Figure 11 is an exploded
pictorial view of the baghouse construction showing this modular construction.
The major modules are the clear air plenum, the side panels, the hopper, the
"tube sheet" (with nozzles and bag collars) and the structural support base.
The last two items are not shown for clarity.
The baghouse was supplied by Miller Industrials, a division of Industrial
Clean Air. All gas-side components are of stainless steel construction for
corrosion protection. The filter bags are 14-ounce felted "Nomex" for high
temperature serviceability on stainless steel cages. All exterior surfaces
are insulated with Johns-Manville "1000" spun glass board protected by a gal-
vanized steel sheathing.
Access to the interior of the baghouse is provided by eight 22-inch
round ports on top of the unit (into the clean air plenum) and a 2-foot by
4-foot door at one end of the unit for bag inspection and servicing.
The screw feeder at the bottom of the hopper is driven by a 3/4-hp elec-
tric motor which brings the collected particulate to the outlet end at 15 rpm
Because of severe height limitations which left no room for installation of a
rotary air lock, the normal technique for removing the particulate out of bag-
houses, a penumatic dust box was installed instead for future pneumatic line
connections to convey the collected material away as it is brought down by the
screw.
34
-------
6LC&KJ
Ul
UOT
Figure 11. Dust Collector Modular Construction
-------
4.7 DUCTING, GENERAL
Since there were some changes in the general tunnel ducting layout be-
tween the design study and the actual as-designed configuration, a few comments
addressing the more obvious and important of these will be made in the follow-
ing paragraphs.
4.7.1 Conditioning Section Cross-Sectional Area
The conditioning section cross-sectional area was changed from 36 ft2 in
the design study to 16 ft2 due to engineering consideration of efficient cool-
ing coil and heater design, already mentioned in the conditioning section dis-
cussion.
4.7.2 Dust Collector Entrance Elbow
In the interest of low pressure drop and good flow quality the dust col-
lector entrance elbow was reconfigured to provide a more gradual right angle
turn and in addition incorporate turning vanes. The turn was made rectangular
in cross section (16 ft2) for ease of fabrication. A transition from square
to round was then incorporated to make the necessary interface with the dif-
fuser outlet.
4.7.3 Expansion Joints
Because of the relatively high temperature achieved in wind tunnel
operation, it was necessary to design into the ducting system means for con-
trolled absorption of thermal expansion, primarily axial, but in some cases
angular, without which large forces would be developed and have to be reacted
by support structures and/or the ducting components themselves.
For this purpose, Aerotherm developed unique, custom expansion joints to
be installed in strategic locations depending on the potential for thermal
growth. Basically two types of flexible devices were developed; these are
shown in Figures 12 and 13.
Figure 12 shows the basic expansion joint scheme. Expansion is accommo-
dated by simply allowing the duct to which the joint is attached seek its own
position, depending on its thermal growth characteristics, by "telescoping"
into an adjacent duct. The joint is sealed by a rolling convolute of impervious
fabric capable of operating at the elevated temperatures.
Figure 13 shows a custom metal bellows type design. It was necessary at
the outlet of the diffuser to absorb not only axial thermal expansion, but also
a thrust load developed in the diffuser itself due to the negative pressure
inside the duct.
36
-------
LIMIT ซ5TOP
U)
-J
TRAVEL,
FABfZlC MSMBJ2ANE
Figure 12. Basic Rolling Convolute Expansion Joint
-------
41
FABRIC
48"[?lA
Figure 13. Bellow Expansion Joint
38
-------
In addition, all of those expansion joints provide points where small
amounts of angular misalignment arising from inherent fabrication and assembly
tolerances could be accommodated.
4.8 CONTRACTION
The usual design condition for a contraction cone in a wind tunnel is
that the velocity at the end of the cone be fairly uniform. The contours se-
lected, of course, must avoid regions of an adverse pressure gradient to pre-
vent flow separation from disturbing the core flow. The details of contraction
design can be very complicated and will not be discussed here except to say
that this particular contraction design was based on the method of Cohen and
Ritchie, a method based on a radial expansion from an adopted axial velocity
distribution, of a series solution of the Betrami differential equations in
the Stokes stream function. If more specific details are desired, consult
Reference 4 at the end of this report.
Of course, any contour design solution by such methods must allow for
the realities of fabrication capabilities. In this case the contour was ap-
proximated by 12 "gore" strips developed on flat stock, shaped to the contour,
and seam welded at the edges. Other methods such as spinning, or approxima-
tion by conical segments were not economically feasible.
4.9 DIFFUSER
The diffuser cone as presented in the design study was one of 3ฐ included
angle approximately 40 feet in length. As installed, the diffuser was shortened
to 20 feet, 6ฐ included angle preceded by 20 feet of 2-foot diameter straight
ducting. The two configurations are shown in Figure 14.
This major design change was incorporated for two reasons, one practical
and the other theoretical:
1. Diffusers are more costly to fabricate than equivalent lengths of
constant area duct.
2. Straight lengths of duct immediately upstream of the diffuser en-
hances its performance whatever its angle by assuring the flow will
be of good quality entering.
Pope and Harper (Reference 3) state conclusively that "with smooth flow
entering a typical wind tunnel diffuser, 5ฐ between opposite walls will yield
satisfactory flow, as will 6ฐ, possibly 7ฐ and probably not 8ฐ ... Even 7ฐ
moves into the questionable category." Fortunately, the wind tunnel configura-
tion conveniently allowed a 20-foot diffuser with 6ฐ included angle, preceded
39
-------
Figure 14. Diffuser Configurations
-------
by the 20 feet (five diameters) of straight section. Considering the economic
factors, the change was an ideal alternative to the original preliminary de-
sign layout.
4.10 AEROSOL GENERATOR AND INJECTION SYSTEM
The emphasis in the design of an aerosol generation system, or "dust
feeder," from the design study to the final design and installation has been
towards simplicity. A more sophisticated system is presently under design for
future installation.
Even the present simple system has seen some developmental changes,
however. The design study presented a system which created an aerosol by di-
rect aspiration of the fly ash by an air ejector. The air ejector was fed di-
rectly by a live-bottom bin. Feed rate control was established by the manipu-
lation of a variable size orifice at the bottom of the bin.
During the initial test and checkout of the tunnel, the above system was
built and installed, modified from the original concept in that the dust feed
rate was controlled by Acrison screw feeder rather than a variable orifice.
Screw feeders have proven capable of providing very accurate feed rate control
for fly ash; feed rates may be changed conveniently and are repeatable to
better than 2 percent.
This system worked reasonably well for short durations, but had long
term reliability problems. These were due to a number of reasons, but the
primary problem was the slow accumulation of fly ash in the aspirator itself,
a phenomenon associated with moisture condensation from the expanding air as it
passed through the aspirator. Such accumulation eventually degraded the over-
all performance and so the system could not be used for long duration tests.
To eliminate this problem, the present system aspirates the dust by a
crude fluidization technique. This solution, shown in Figure 15, should be
considered interim until the more sophisticated system can be installed.
The dust is introduced into a "pressure pot" through which air is passing
at a sufficient velocity to remove the particulates or agglomeration of parti-
culates small enough to have terminal velocities lower than the internal air
velocity. As a result, these particulates are carried away and transported to
the tunnel by the approximately 5 psi potential in the fluidization container
through a 3/4-inch vinyl tube. If the particulate agglomerations are too large
to be carried away, they are "churned" inside the chamber until they are deag-
glomerated sufficiently well to be transported to the tunnel. This highly con-
centrated dust-laden flow is split into eight separate streams for injection
into the stilling chamber.
41
-------
Figure 15. Aerosol Generation System
-------
Actual sampler comparison tests have been conducted using this system
and it has been shown to be repeatable and reliable. However, it should be
pointed out that particle size distributions have not been investigated, so it
is not known to what degree this system is capable of deagglomerating the bulk
fly ash to its original constituent size distribution.
4.11 CONTROLS AND INSTRUMENTATION
The basic requirements for the controls and instrumentation system, de-
fined in Reference 1, were followed in the final design. Complete control re-
quired for startup, regulation and shutdown of tunnel components is accom-
plished from the mezzanine. Parameters that are controlled from the operating
console are the following:
Test gas velocity
Test gas temperature
Inlet, exhaust and tunnel damper valve position
Test gas humidity
Combustion products injection
Dust injection
Dust collector pulse cleaning frequency
Control devices also on the mezzanine, but not a part of the console,
are control valves for chilled water flow to the tunnel chiller, chilled water
to the combustion products generator heat exchanger and the steam flow valve to
the steam humidifier.
In addition to control functions, the console includes meters for moni-
toring tunnel velocity and temperatures and pressures that are critical to the
proper operation of the wind tunnel. Indicator lights shown the operational
status of the various system components. Safety interlocks are included in
control operations to protect against potential hazards to personnel and equip-
ment. A fault light display and alarm horn notify the operator if certain
operating limits are being exceeded. A key switch on the console controlling
power to all subsystems prevents tunnel operation by unauthorized personnel.
The console panel is shown in Figure 16. The controls and meters are on
standard 19-inch wide panels mounted in vertical twin rack assemblies which are
bolted together. Each panel is assigned to a specific subsystem, thus simpli-
fying console operation and providing minimum disruption in the even mainte-
nance or modification is required on a given subsystem.
43
-------
Figure 16. Test Facility Control Console
44
-------
A complete description of how the tunnel is controlled is contained in
Reference 2. All control systems are electrically operated except for the com-
bustion products diverter valve and the steam humidifier control valve, which
operate pneumatically.
This section summarizes how each subsystem is controlled, with block
diagrams for clarification where necessary. Appendix A outlines the basic pro-
cedure for operating the particulate wind tunnel.
4.11.1 Fault Lights
The design study identified a tentative list of tunnel conditions that
should be flagged by an alarm or fault system. A summary of the faults designed
into the control console is presented in Table VII. Each fault operates a
light allocated to that fault as well as an alarm horn. Certain faults inter-
lock with other parts of the control system for automatic control of a poten-
tial hazard; other faults only alert the operator to take action or monitor
the situation.
4.11.2 Velocity Control
Velocity control is maintained primarily by fan speed control with the
tunnel damper as an auxiliary control. A block diagram of the fan speed con-
trol system appears in Figure 17. The fan control was designed so that the
tunnel velocity may be controlled by operator adjustment of the clutch coupling
through the adjustment dial on the console or in the automatic mode by feed-
back control employing a built-in analog computer1. In either mode of operation
tunnel velocity is computed automatically from the tunnel contraction section
static pressure drop and absolute temperature.
The velocity computer has three prime tasks:
1. Conversion of a thermocouple voltage to an absolute temperature
analog.
2. Computation of the velocity by implementing a preprogrammed formula.
3. Interfacing to the pressure transducer and to the clutch controller.
In the automatic mode, the velocity computer serves as the summing point
in the velocity control system. As such, it compares the set point defined by
the velocity control (console dial) to the computed value and applies the error
(residual) to maintain the difference at a minimum. Additionally, the initial
conditions of the controller are set by the velocity computer in manual mode so
that relatively "bumpless" transfer occurs when switching to automatic mode.
'The computer was designed by the Products Division of Acurex Corporation.
45
-------
TABLE VII
FAULT LIGHTS AND HORN ALARM
Title
Actuated
By
Interlocked
Control Functions
Tunnel over temp.
Heater over temp.
Chiller over press.
Low tunnel velocity
Tunnel inlet valve
open
Low air press.
Tunnel temp, low
Boiler fuel limits
Boiler flame failure
Boiler water low
Boiler over temp.
Boiler heat ex-
changer off
Explosive mixture
Test sect, inlet exceeds 500ฐF
Modulating or Aux. heater
elements exceed overtemp.
setpoint (1200ฐF recommended)
Chiller exceeds 120 psi
Tunnel velocity not adequate
for operation of auxiliary
heaters
Tunnel inlet (from laboratory) not
closed; fault not operative if
tunnel damper closed for purging
Compressed air press, is too low
to operate explosive mixture de-
tector, humidifier, and diverter
valve
Tunnel temp, below 170ฐF (com-
bustion products dewpoint),
when boiler is on
Boiler fuel press, exceeds
the range of 5.5" to 20" W.G.
Boiler flame failure
Boiler water level below safe
level
Boiler water temp, exceeds
250ฐF
Recirculation pump off or
chilled water not flowing
in boiler heat exchanger,
when boiler is on
Gas mixture approaching ex-
plosive level in boiler
exhaust stack (with di-
verter to exhaust) or in
tunnel (with diverter to
tunnel)
Shuts off heater system
No effect on tunnel systems
Shuts off boiler and swings
diverter valve to exhaust
No effect on tunnel systems
20% lower explosive limit
swings diverter valve to
exhaust
40% lower explosive limit
shuts off boiler
46
-------
MCTTOI2
STAI2TER
r
CONSOLE
Figure 17. Velocity Control System
-------
4.11.3 Temperature Control
Feedback control of the tunnel heater power is employed to achieve any
temperature set point between the limits of 70ฐF and 450ฐF. The cooling coil
is manually throttleable and is intended to be used as a cooling element for
test conditions near ambient temperature. Its purpose in temperature control
is to remove dissipated fan power. Reheat will be required to maintain accu-
rate temperature control.
The heater power supply is 480-3<|>-60 Hz. The two auxiliary (heat-up)
heater modules are wired in identical circuits of 62.5 kw each and are operated
by a set point controller which deactivates the heaters when set point is
reached in heat-up. The third heater module is the modulating heater, wired in
a 75 kw circuit, which is controlled by an SCR controller package to continu-
ously maintain accurate set point. Thermocouples located at the test section
inlet are connected to the modulating heater controller and the auxiliary
heater controller.
A thermocouple is welded to a heater element of auxiliary heater no. 1
and to an element of the modulating heater, providing a means of sensing ex-
cessive element temperatures. A pressure switch (in the console) coupled to
the contraction section AP manifold provides for signalling the operator with
a fault light if tunnel velocity is too low to safely use the high watt density
auxiliary heaters.
Temperature measurements at the following locations in the tunnel are
displayed on meters on the console tunnel temperatures panel.
1. Test section inlet
2. Test section outlet
3. Dust collector outlet
4. Temperature control (gas conditioning) section inlet
5. Temperature control section outlet
6. Humidity sensor
For tunnel startup to an elevated temperature, the normal mode of opera-
tion is to operate the fan at nearly full velocity in order to maximize the
effectiveness of the heater elements. Set points will be adjusted on the modu-
lating heater control and the auxiliary heater control. Auxiliary heater power
may be cut in half by operating auxiliary heater no. 1 only. Auxiliary heater
no. 2 will not operate independently. When set point is achieved, the auxiliary
heaters will cut out and not reactivate unless the manual reset button is de-
pressed. Tunnel velocity may then be adjusted to the desired set point. The
48
-------
modulating heater functions throughout the test run as required on Thyristor
(SCR) control to maintain set point.
A schematic of the chiller is shown in Figure 18. Chilled water flow is
controlled by hand-operated valves located on the mezzanine. A drain valve
provides capability for emptying the coil when test conditions exceed 180ฐF.
Compressed air applied to the vent valve can be used to force all water from
the coil. Safety features to handle the possibility of steam forming in the
coil include an over pressure switch which shuts down the heater system at
120 psi in the coil and a relief valve which opens at 140 psi. The preceding
settings may be adjusted. A system fault is announced at the 120 psi level.
The chiller section of the control console includes 1) a status light
coupled to the water flow switch shown in Figure 18, and 2) a meter showing
the chiller inlet and outlet water temperatures.
4.11.4 Humidity Control
A schematic diagram of the humidifer system is shown in Figure 19.
#
Steam is supplied to the humidifier control unit by means of a manual
valve on the mezzanine. The steam controller is a pneumatically actuated valve
attached to the humidifier. The penumatic controls are operated from the con-
trol console. Air is supplied to these controls via the manual laboratory air
valve on the mezzanine.
Operation consists of the following procedures:
1. Upon achievement of temperature set point and after the tunnel is
charged with combustion products (if required), the humidifier is
turned on by manually opening the steam valve and electrically open-
ing the control air solenoid valve.
2. Adjustment of the control air pressure by means of the pressure
regulating valve (venting type) controls the diaphragm-actuated
steam regulating valve from closed at 3 psig to maximum position
at 10 psig.
3. An aspirator, operating on laboratory air, draws tunnel gases past
a humidity sensor that will operate up to 120ฐF. (The measurement
system was designed for the range 70ฐF - 100ฐF.) The humidity
measurement appears on the console meter. Since the tunnel gas
may have cooled in transit to the detector, a temperature meas-
urement must also be made and the relative humidity corrected to
the tunnel temperature at the test section inlet.
49
-------
TO
Ul
o
TUNNEL.
FLOW
FROM
FACIL
COOLEK
Figure 18. Chiller Schematic
-------
WAY
VALV/E
CONTROL,
SUPPLY
100 PS IS
I
STEAM I2E6ULATIN6
VALVE
HUMIDITY PETeCTOe.
Figure 19. Humidity Control System
-------
4. As the humidity set point is approached, the air pressure regulating
valve will be adjusted to achieve a smooth approach.
5. If humidity exceeds set point and the chiller is operating for tem-
perature control, the humidifier flow is reduced with the pressure
regulating valve. The chiller will continue to condense moisture
from the gas.
6. The humidifier is shut off from the console pushbutton which vents
the solenoid valve, closing the steam valve.
4.11.5 Purge Section Control
Control of the purge section valves is maintained from the console by
means of toggle switches. A position potentiometer on each valve is read out
on a panel meter indicating percent of full open position. Limit switches on
the tunnel damper and the inlet valve actuate the panel limit lights indicating
the valves are either fully closed or fully open. The limiting positions of
the exhaust valve are not critical and therefore not indicated with lights.
It is important to insure the closed status of the inlet valve so that test
gases do not enter the laboratory area. Therefore, a fault light indicates
when the inlet valve is not closed. The fault light is automatically deacti-
vated during purge by means of the closed switch on the tunnel damper.
4.11.6 Combustion Products Control
The combustion products system is controlled from the console. Refer
back to Figure 10 for the combustion products system schematic diagram. The
system is started by 1) opening the flow valves to the coolant side of the
heat exchanger (located on the mezzanine), 2) starting the boiler recirculation
pump, and 3) activating the "boiler on" switch at the console. There will be a
fault signal if the boiler is activated without coolant flow or recirculation
pump on. Until the boiler is turned on, the combustion products diverter valve
is unpowered and, therefore, cannot be moved from the exhaust position. Boiler
ignition activates the console flame-on light on the console.
Controls in the boiler-mounted control package automatically proceed
through a normal start sequence with the appropriate interlocks and flame safe-
guard features. Wind tunnel control console relays are connected to the fol-
lowing switches internal to the boiler:
1. Low water cutoff
2. High water temperature cutoff
52
-------
3. High and low gas pressure limits
4. Flame failure
Any one of the above problems will shut the boiler down and alert the operator
to the situation by fault alarms (light and horn) at the console.
To guard against the hazard of an explosive mixture of gas forming in
the wind tunnel, a combustible mixture detector, calibrated for natural gas, is
connected to the tunnel and the combustion products 6-inch duct by means of
an aspirating draw system. The aspirator begins drawing air automatically
with boiler turn-on. The detector control package is mounted on the console
and provides two alarm levels, 20 percent of the lower explosive limit (LEL)
and 40 percent LEL. The console fault light operates on signal from the de-
tector electronics. In the "exhaust" mode, the detector sample is drawn from
the 6-inch duct. When the combustion products are diverted to "tunnel," a
three-way solenoid valve in the detector draw line automatically switches the
measurement to the tunnel. To insure that the aspirator is properly powered
by laboratory compressed air, an air pressure switch signals a console fault
alarm if the compressed air pressure is low. (The alarm also indicates that
the diverter valve pneumatic actuator and the humidifier pneumatic valve will
not operate effectively until laboratory air pressure is increased.) As well
as actuating the fault alarm, the 20 percent LEL alarm diverts boiler gases to
exhaust. At 40 percent LEL, the boiler is shut down.
Due to the risk of moisture condensation, the tunnel temperature, par-
ticularly at the baghouse, should be above approximately 170ฐF before combus-
tion products are allowed to enter the tunnel. Therefore, when the boiler is
on, a temperature switch located at the baghouse exit, will signal a console
fault alarm until the tunnel temperature exceeds 170ฐF. The diverter valve is
not interlocked to the temperature switch so operator judgement is required
here.
In order to operate the boiler at optimum combustion efficiency, the
draft damper position is controlled by the operator from the console. This
valve is normally open, and is operable from the console only during flame-on
condition. A pressure gauge is included on the console to provide direct read-
out of draft pressure. During boiler operation, the gauge should indicate
+ 1/2 inch to 1 inch W.G. To assist in monitoring the boiler exhaust, a second
pressure gauge measures tunnel pressure at the purge section outlet (that is;
the boiler exhaust back pressure).
Measurements on the console assigned to the combustion products system
temperatures panel include the following temperatures:
53
-------
1. Combustion products gas (at the boiler exhaust)
2. Boiler water inlet
3. Boiler water outlet
4. Boiler heat exchanger inlet
5. Boiler heat exchanger outlet
Boiler water pressure is also displayed on the console. Normal operat-
ing pressure is about 20-25 psig. To avoid moisture condensation in the stack,
the combustion products gas temperature should be kept between 300ฐF and 350ฐF.
When the boiler achieves steady state operation (about 20 minutes) and
tunnel temperature exceeds 170ฐF at the dust collector exit, the diverter valve
is actuated to the tunnel position.
When tunnel charging is completed (as determined by a detection system
external to the control console) the operator will swing the diverter valve to
exhaust and probably continue boiler operation in preparation for recharging
as required due to dilution from tunnel leaks.
4.11.7 Dust Collector Control
There are two functions on the dust collector which are controlled: the
bag cleaning function and the hopper cleanout. Only the former is initiated
from the control console. Hopper cleanout will be achieved when the tunnel is
not operating by activating a motorized screw in the hopper at an adjacent
circuit breaker.
The switch on the control panel activates the bag cleaning controller
located on the baghouse. This controller performs the following functions:
Controls the duration of the cleaning air pulse (adjustable)
Controls the period between pulses (adjustable)
Controls the cleaning air in a prescribed manner to 12 groups of
bags via 12 solenoid valves
The baghouse pressure drop is displayed on the control panel with a dif-
ferential pressure gauge.
54
-------
REFERENCES
1. Anderson, L. W., Lapson, W. F., and Schaefer, J. W., "Design of a Particu-
late Aerodynamic Test Facility," Aerotherm Final Report No. 71-43, Decem-
ber 7, 1971.
2. "Particulate Aerodynamic Test Facility, System Description and Operations
and Safety Manual," Aerotherm User's Manual, UM-73-39, March 1974.
3. Pope, Alan and Harper, John J., Low Speed Wind Tunnel Testing, John Wiley
and Sonse, Inc., 1966.
4. Cohen, M. J. and Ritchie, N. J. B., "Low Speed Three Dimensional Contrac-
tion Design," Journal of the Royal Aeronautical Society, Vol. 66, April
1962, p. 231.
55
-------
APPENDIX A
TEST FACILITY OPERATION PROCEDURE
This section outlines the basic procedure for operating the test facil-
ity. It is presented in enough detail to provide a working knowledge of tunnel
operation.
Figure A-l shows the locations on the tunnel of the hatches, breaker
boxes, thermocouples, and pressure taps. Table A-l is the key to Figure A-l.
Table A-2 contains the test facility startup and operation procedure.
The startup description begins with the circuit breaker boxes and proceeds
through all of the facility subsystems. In the text, words consisting of all
uppercase letters denote labels as they appear on the control console or else-
where .
Under normal circumstances the shutdown procedure for individual sub-
systems is the opposite of the steps in Table A-2. There is, however, a cor-
rect order in which the subsystems should be deactivated, as delineated in
Table A-3. The normal shutdown procedure assumes as an initial condition that
all tunnel subsystems are activated.
There are several instances during which a malfunction in a tunnel sub-
system will require a specialized operation procedure. These activities are
briefly outlined below:
If the fan becomes disabled during a test run, the tunnel should
remain sealed off from the room, all subsystems deactivated, and
the test gas purged from tunnel by the repaired fan or other means.
If one or more of the heater modules overheat, and the automatic
heater over-temperature control fails to operate, deactivate the
system and operate the fan for a length of time sufficient to cool
the modules.
If condensation occurs on the dust collector bags, purge the tunnel
in conjunction with the heater system until the filter media are
fully dry.
This is not an exhaustive list, since straightforward solutions to such
difficulties are usually discovered when operator judgement and discretion are
applied.
56
-------
U1
-J
Figure A-l. Plan View of Installation
-------
TABLE A-l
KEY TO FIGURE A-l
ITEM
DESCRIPTION
1 Breaker box 1
2 Breaker box 2
3 Breaker box 3
4 Breaker box 4
5 Breaker box 5
6 Turning box hatch, before vanes
7 Turning box hatch, after vanes
8 Stilling section hatch
9 Diverging section hatch
10 Baghouse access door
11 Conditioning section inlet thermocouple
12 Conditioning section outlet thermocouple
13 Test section inlet thermocouple
14 Velocity computer thermocouple
15 Auxiliary heater controller thermocouple
16 Modulating heater controller thermocouple
17 Conditioning section outlet thermocouple
18 Baghouse outlet thermocouple
19 Contraction section AP tap, low velocity
20 Contraction section AP manifold tap, high velocity
21 Tunnel low temperature switch
22 Tunnel over-temperature switch
23 Combustible gas detector
24 Combustible gas detector tap, exhaust
25 Combustible gas detector tap, tunnel
26 Humidity detector tap
58
-------
TABLE A-2
TEST FACILITY START-UP AND OPERATION PROCEDURE
ITEM
COMMENTS
1.
2.
Breaker and Junction Boxes
A. 'Box 1, Switches ON:
1) Unnumbered
2) Unnumbered
3) Unnumbered
Box 2, Switch outside lever ON:
B.
C.
Box 3:
1) Switch outside breaker lever ON
2) Dial overtemp controls to desired setpoints
3) Reset both heater overtemp controls
0. Box 4, Switches ON:
1) I 30
2) # 32
Verify secured hatches
A. Turning box, before vanes
B. Turning box, after vanes
C. Contraction section
0. Diverging section
C. Baghouse access door
3. Manually rotate fan one revolution by the fan belt
4. Open compressed air supply valve.
5. If tunnel is to be operated above 180ฐF and tunnel
chiller will not be used, drain chiller.
6. Activating console panel:
A. Turn panel POWER switch ON with key
B. Panel initial conditions
1) All subsystem power switches should be off.
2) All fault lights, unlit
Refer to Figure A-l
Heater, 440V
Fan motor, 440V
Baghouse auger, 220V
Fan motor, 440V
Heater Overtemp Control Box
Recommended maximum setpoints:
Modulating heater: 1200ฐF
Auxiliary heaters: 1200ฐF
Marked "PF"
Console and boiler, 220V
Boiler, 110V
Check for obstructions
Supplies air to all pneumatically-
operated subsystems.
All switches except those for the heaters
normally have defaulted to the OFF or
MANUAL positions before initial console
activation.
Correct any indicated faults before
proceeding
59
-------
ITEM
COMMENTS
Tunnel Fan
A. Set TUNNEL VELOCITY dial to zero
B. Adjust TUNNEL DAMPER POSITION to OPEN
C. Turn FAN POWER switch ON.
D. For automatic velocity control, switch VELOCITY
CONTROL to AUTO at this time.
E. By monitoring the test section VELOCITY meter,
approach the desired velocity by slowly increasing
the dial setting
F. Inspect fan for smooth, quiet rotation and that down-
stream pressure readings are steady.
8. Tunnel Chiller
A. Open chiller water inlet and outlet valves
B. Verify illumination of CHILLER ON lamp
C. During operation, keep CHILLER WATER OUTLET tempera-
ture below - 65ฐF.
9. Heater System
(Note: Procedure assumes breaker box 3 is
activated)
A. Turn No. 1 or both auxiliary heaters ON
B. Dial in desired tunnel temperature setpoint
C. Press auxiliary heater RESET button
D. Turn modulating heater switch ON
E. Dial in desired tunnel temperature setpoint
F. At setpoint attainment:
1) DEGREES DEVIATION meter reading s 0
2) Auxiliary heaters turn off and must be manually
reset for further operation
3) Power supplied to modulating heater diminished
G. During tunnel shutdown, always deactivate heaters
before fan
10. Humidity Control System
A. If tunnel is to be operated below 120ฐF, open humid-
ity detector aspirator and toggle valves.
B. Open steam inlet valve
A slight fan speed surge will be
noted if control mode is switched to
AUTO above ~ 10 fps tunnel velocity
Lubricate bearings after every 200
hours of operation.
If humidifier is on at this point,
chiller may cause condensation in the
tunnel
If this is impossible, tunnel is
operating too hot for the chiller.
Close valves and drain the chiller
before continuing.
Max. Tunnel Temp. 450ฐF; Tunnel
velocity must be above ~ SOfps before
heater activation
Heater No.2 will not operate indepen-
dently of No. 1
Verify ON lamp, illuminated
Used to maintain tunnel temperature
during testing
Glowing intensity of OUTPUT L.E.D. is
proportional to power supplied to the
heater.
Refer to Chroma 1 ox mannual for modu-
lating heater proportional band and
manual reset adjustment.
60
-------
ITEM
COMMENTS
C. On HUMIDITY CONTROL panel:
1) Verify illumination of STEAM ON lamp
2) Turn CONTROL AIR switch ON
3) Modulate control air pressure until desired
humidity is reached
11. Combustion Products Generator System
A.
Open heat exchanger and boiler water inlet and outlet
valves.
Verify:
1) Operation of lab facility chiller
2) Proper water level in expansion tank sight glass:
Just above lower end of glass tube.
Shutoff Cocks in burner and pilot gas lines, open
3)
4)
Proper pressures in pilot gas line: Before reg-
ulator, ~ 5 psig; after regulator, - 15" W.G.
5) High and low gas pressure switches, reset
6) Low boiler water switch, reset
7) BOILER HEAT EXCH. INLET temperature - 45ฐF
C. On COMBUSTION PRODUCTS CONTROL panel:
1) Verify DIVERTER VALVE POSITION = EXHAUST and
DRAFT VALVE POSITION =OPEN
2) Test COMBUSTIBLE GAS ALARM system
3) Turn RECIRCULATION PUMP switch ON
4) Turn BOILER switch ON
5) Verify FLAME ON lamp, illuminated
6) Verify BOILER DRAFT = 1/2" to 1" W.G.
7) During operation be sure that:
a. BOILER MATER pressure < - 20 psig
b. BOILER MATER INLET temperature > 170ฐF
c. BOILER WATER OUTLET temperature < 200ฐF
d. BOILER HEAT EXCH. OUTLET temperature < 65ฐF
Calculate tunnel relative humidity by
converting meter RH at humidity de-
tector temperature to RH at tunnel
temperature employing a psychrometric
chart
Valves should be inoperable from con-
sole during flame-off
Recalibrate system every 3 months
Subsequent automatic start sequence:
1. 15 (second boiler pre-purge by
blower
2. Combustion Air Proving Switch,
activated
3. Igniter spark, activated
4. Pilot gas line solenoid valve, open
5. Pilot flame, on
6. Burner gas line motorized valves,
open.
7. Flame on
8. Pilot gas line solenoid valve, closed
If necessary to attain proper draft,
modulate DRAFT VALVE POSITION
61
-------
ITEM
COMMENTS
11. (continued)
G.
e. COMBUSTION PRODUCTS GAS temperature above
300ฐF, by adjusting heat exchange and boiler
water inlet and outlet valves
Visually inspect flame for stability and color-
yellow with blue tinge
H. Verify combustible mixture detectorrotometer setting:
- 1.75 - 2.0 scfh when boiler is operating.
I. Verify Combustible mixture detector aspirator pres-
sure: - 10 - 15 psig
Combustion Products Generator System Operating Modes
(note: procedures assume fan is operating)
1) Boiler off; valve positions
a. Draft, open
b. Diverter, exhaust
c. Inlet, closed
d. Exhaust, open
e. Tunnel damper, open or modulated
2) Boiler on, exhaust to stack
a. Initially, operate tunnel in mode 1)
b. Implement new valve positions:
(1) Draft, open
(2) Divcrter, exhaust
(3) Inlet; open
(4) Exhnust, closed
(5) Tunnel damper, open or modulated
c. Activate corrbustion products generator
system.
3) Boiler on, exhaust to tunnel
a. Initially, operate tunnel in mode 2)
b. Raise DUST COLLECTOR OUTLET temperature to
steady state 170ฐF, minimum. Monitor there-
after.
c. Implement new valve positions:
(1) Draft, open or modulated
(2) Diverter, tunnel
(3) Inlet, closed
(4) Exhaust, open
(5) Tunnel damper, open or modulated
d. When tunnel is fully charged with combustion
products, return to modes 1) or 2)
Prevention of condensation in the
the stack.
Marginal adjustment can be made by
varying position of combustion air
damper plate
Refer to Figure A-2 (a)
Pressure datum
Refer to Figure A-2 (b)
Pressure datum
Refer to Figure A-2 (c)
Prevention of condensation in tunnel
and baghouse
62
-------
ITEM
COMMENTS
11. (continued)
4) Tunnel Purge
a. Initially, operate tunnel in mode 1)( or,
mode 2)with boiler off)
b. If water vapor is judged to be present in
the tunnel, keep DUST COLLECTOR OUTLET temp-
erature above 170ฐF
If operating, close down humidifier
Turn on boiler blower motor switch
Implement new valve positions
(1) Draft, open
(2) Diverter, exhaust
(3) Inlet, open
(4) Exhaust, open
(5) Tunnel damper, closed or modulated
When tunnel is judged fully purged, return
to mode 1)
12.
c.
d.
e.
Aerosol Generator and Dust Collection System
A. Prepare aerosol generator for operation
(procedure to be supplied later)
B. Breaker Box 5; Switches ON:
1) Outside breaker lever
2) Power pushbutton switch
C. On DUST COLLECTOR panel, turn PULSE CLEAN TIMER to
ON.
D. On PARTICULATE GENERATOR panel, turn power ON
E. Adjust reading on CARRIER AIR meter from
dust generator location
F. Keep DUST COLLECTOR AP meter reading < 8" W.G.
G. Operate tunnel and dust generator in conjunction
with combustion products generator system as
shown in Figure A-2.
Refer to Figure A-2 (d)
Prevention of condensation in the
tunnel
Dust auger control box; Heater overtemp
box must be on for this box to activate
(Operate dust auger in conjunction
with bulk handling system)
63
-------
TABLE A-3
TEST FACILITY NORMAL SHUT-DOWN PROCEDURE
(Assumes All Subsystems Are Initially Activated)
Item
Item Referenced in
Table 9-2
1. Turn off aerosol generator system
2. Turn off boiler and heat exchanger pump, manually turn
on boiler blower
3. Shut off chilled water supply to tunnel chiller and
boiler heat exchanger
4. Turn off humidity control system
5. Deactivate humidity detector
6. Shut off steam supply
7. Turn off heater(s)
8. Reduce test gas velocity to <30 fps in test section
9. Proceed to purge tunnel
10. Upon completion of purge, reset tunnel valves to
normal positions and shut off boiler blower
11. Reduce test gas velocity to zero
12. Shut off tunnel fan
13. Shut off control console
14. Shut off compressed air supply
15. Turn off circuit breakers
12
11
8, 11
10
10
10
9
7
11
11
7
7
6
4
1
64
-------
Tunnel Exhaust
1 1 ฎ 1 1 ฎ ^
t -ซ- -ซ- ^
mi
I
1 zz
$ j
Inlet
Boiler Off
Tunnel
Mill
1 r
Boiler
Tunnel
tH
1
Boiler
Tunnel
L
.
Exhaust
1 + 1 From
1 vp^ Boiler
ฉurV^
Inlet
On, Exhaust to Stack
Exhaust
1 L From
i(~r Boiler
r^r^
Inlet
on, Exhaust to Tunnel
Exhaust
MSl-1 LIง^ From.
ul Boiler
I ^Z^ Blower
f ป J Only
( 1 ฎHrฎ
t
Valve Positions
Draft
(not shown
Open
Open or
Modulated
Open or
Modulated
Open
ฉ*ฉ
Diverter
Exhaust
Exhaust
Tunnel
Exhaust
Inlet
Closed
Open
Closed
Open
Exhaust
Open
Closed
Open
Open
(i)
Tunnel
Damper
Open or
Modulated
Open or
Modulated
Open or
Modulated
Closed or
Modulated
Inlet
(d) Tunnel Purge, Boiler Off
Figure A-2. Combustion Products Generator System Operating Modes
65
-------
APPENDIX B
Aerotherm Final Test Report 74-107
TEST PHASE OF PROJECT 7086
ENGINEERING SERVICES SUPPORT OF
PARTICIPATE AERODYNAMIC
TEST FACILITY
66
-------
Aerotherm Project 7086
July 15, 1974
Aerotherm Final
Test Report 74-107
TEST PHASE OF PROJECT 7086
ENGINEERING SERVICES SUPPORT OF
PARTICULATE AERODYNAMIC
TEST FACILITY
by
Dale R. Blann
Hans J. Dehne
L. W. Anderson
Contract No. 68-02-1318
Task Order No. 1
Prepared for
U. S. Environmental Protection Agency
Research Triangle Park
North Carolina 27711
67
AEROTHERM
ACUREX Corporation
-------
TABLE OF CONTENTS
Section Page
1 INTRODUCTION 71
2 SUBTASK 1: VELOCITY PROFILES 72
2.1 Objective 72
2.2 Approach 72
2.3 Apparatus 72
2.4 Test Procedures 77
2.5 Test Results 77
2.6 Conclusions 102
3 SUBTASKS 2 AND 3: PARTICIPATES TESTING
AND ISOKINETIC SAMPLER COMPARISON 103
3.1 Objectives 103
3.2 The Approach 103
3.3 Test Apparatus 104
3.4 Test Program and Results 108
3.5 Conclusions 113
68
-------
LIST OF FIGURES
Figure Page
1 Velocity Profile Probe and Grid 73
2 Stagnation Pressure Probe and Traverse Bar 74
3 Static Pressure Probe 75
4 Particulate Aerodynamic Test Facility for EPA
(DORSEY) Control Systems Laboratory 76
5 Velocity Distribution 78
6 Velocity Distribution 79
7 Velocity Distribution 80
8 Velocity Distribution 81
9 Velocity Distribution 82
10 Velocity Distribution 83
11 Velocity Distribution 84
12 Velocity Distribution 85
13 Velocity Distribution 86
14 Velocity Distribution 87
15 Velocity Distribution 88
16 Velocity Distribution 89
17 Velocity Distribution 90
18 Velocity Distribution 91
19 Velocity Distribution 92
20 Velocity Distribution 93
21 Velocity Distribution 94
22 Velocity Distribution 95
23 Velocity Distribution 96
24 Velocity Distribution 97
25 Velocity Distribution 98
26 Velocity Distribution 99
69
-------
LIST OF FIGURES (concluded)
Figure Page
27 Velocity Distribution 100
28 Velocity Distribution 101
29 Basic TAsk 3 Test Arrangement 105
30 Aerosol Generation System 106
31 Initial Injection Line Arrangement 109
32 Dust Profiles - Dorsey Tunnel Test Section
Velocity 60 fps 110
33 Dust Profiles - Dorsey Tunnel Test Section
Velocity 90 fps, 60 fps, 30 fps 111
34 Final Injection Line Arrangement 112
35 Final Concentration Profile for Subtask 3 114
70
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SECTION 1
INTRODUCTION
In response to Task No. 1 under Contract 68-02-1318, Aerotherm Division
of Acurex Corporation has provided engineering services to plan and conduct
preliminary tests in the Particulate Aerodynamic Test Facility to establish
its utility as a basic test bed for Control Systems Laboratory research pro-
grams .
Three subtasks were accomplished:
1. Establish invicid core flow zones at four axial stations and three
operating conditions
2. Conduct particulate sampling tests at typical facility operating
conditions to establish particulate loading profiles across the
duct
3. Conduct an experimental comparison of isokinetic particulate sam-
pling instruments.
Modifications were made during the testing, as necessary, to improve
system performance.
Subtask 1 is described in detail in Section 2 below. Subtasks 2 and 3
were closely related and were carried out together; thus they will be de-
scribed in conjunction in Section 3.
71
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SECTION 2
SUBTASK 1: VELOCITY PROFILES
2.1 OBJECTIVE
The objective of Subtask 1 was to establish the invicid flow core re-
gions in the wind tunnel test section at four axial positions and at three
operating conditions.
2.2 APPROACH
The approach to meeting the objectives was to make pitot tube traverses
vertically and horizontally at each of the axial stations and at each of three
operating conditions, and to calculate, based on the measured static and stag-
nation pressure data, the local air velocity at each of the profile grid
points. The calculated velocity data was then plotted graphically to obtain
"velocity profiles" at each axial station in both the vertical and horizontal
directions.
2.3 APPARATUS
The test set-up for taking the velocity pressure data is shown in Fig-
ure 1: the details of the probes are shown in Figures 2 and 3. Two probes
were used: 1) a total pressure probe which measured stagnation pressure and
2) a static pressure probe which indicated local duct static pressure.
The static probe was stationary. It was mounted through one of four
ports located at each axial station. The stagnation probe was attached to
an aluminum tube which penetrated the test section through conax fitting in-
stalled into diametrically opposed prot holes. It was of sufficient length
to allow the probe to be positioned at any point across the duct.
Manometer tubing was attached to each probe. For greater sensitivity
a 3 inch inclined manometer was used to measure differential pressures be-
tween the static and stagnation probe, which by definition, is velocity pres-
sure.
The basic layout of the Particulate Aerodynamic Test Facility is shown
in Figure 4. The fan is an airfoil centrifugal type driven by a 50 H.P. vari-
able speed drive. The air (or combustion products, if desired) is "conditioned"
72
-------
fU*1
tEHEEQ
TVfl^AL.
73
-------
Figure 2. Stagnation Pressure Probe and Traverse Bar
-------
DMX HOLES
PLACES
z.a
J t
Figure 3. Static Pressure Probe
75
-------
Figure 1. Model of Partlculate Aerodynamic Test Facility
-------
downstream of the fan prior to the first turn. The conditioning section con-
sists of a duct heater (resistance heating), duct chiller (air-to-water heat
exchange), and humidfier (steam).
The test section is 2 feet in diameter which gives a contraction ratio
of 9 to 1. Particulates may be injected (as described in sections below)
which are subsequently removed by a bag-type dust collector. The gas returns
to the fan to complete the circuit.
2.4 TEST PROCEDURES
The test program was straightforward. Both probes were installed into
a given test section axial location and the tunnel air velocity adjusted at
the control console to indicate a given nominal test section velocity. The
tunnel velocity controller was switched to AUTO in order to hold that velo-
city, and the tests were conducted. Three nominal test section velocities
were used: 30, 60, and 90 fps. The probes were kept in position at each
axial location until all data at the three different velocities were attained;
then they were moved to a new axial location.
The stagnation probe was sequentially positioned across the duct at
pre-determined intervals by scribe marks on the traverse road. These scribe
markes were made to provide 1/4 inch increments for a distance of 3 inches
from each wall and 1 inch increments in between (core region).
2.5 TEST RESULTS
The velocity profile data is plotted in Figures 5 through 28 for each
nominal velocity, sequentially by test section. A single data point at a
given "x" location indicates that the pressure reading from the manometer was
steady; two points indicate a measureable fluctuation could be observed, so
max-min was recorded. No attempt was made to average over the test time-
increment at such points.
The horizontal profiles show the expected uniform core flow in the
center with a boundary layer developing along the wall. Boundary layer thick-
nesses range from 1/2 to 4 inches depending on velocity and axial position.
Test section 1 does show, for both 60 and 90 fps, some local distortion in
the profiles, but since it disappears by test section 2, it is attributed to
the presence of the dust injector nozzles in the stilling chamber.
The vertical profiles, however, present more difficulty in interpreta-
tion. As one scans the vertical velocity profiles from test section 1 to 4,
it is apparent, particularly at the higher velocities, that the flow is being
77
-------
g '
:J.: U
Figure 5. Velocity Distribution
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Figure 8. Velocity Distribution
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Figure 9. Velocity Distribution
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Figure 11. Velocity Distribution
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Figure 12. Velocity Distribution
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Figure 13. Velocity Distribution
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Figure 16. Velocity Distribution
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Figure 20. Velocity Distribution
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Figure 26. Velocity Distribution
-------
Figure 27. Velocity Distribution
-------
Figure 28. Velocity Distribution
-------
skewed towards the bottom of the tunnel. Also, the upper portion of the
tunnel, in addition to being of lower average velocity, seems, as indicated
by the scatter in the max-min data points, to possess greater turbulence.
The exact reason for this behavior is unclear, but the most likely ex-
planation (without benefit of further testing) is that it is related to the
180ฐ turn at the end of the test section. The flow seems to be adjusting
itself to go around the turn. The disturbance may be caused by a stall in
the turn at higher velocities; it is well known that flow disturbances in
subsonic flow can be propagated well upstream of the actual cause of the dis-
turbance .
It was observed during testing that the presence of a 3 inch diameter
probe in test section 3 partially alleviated the problem, probably due to the
vorticity added to the flow by its presence. Consequently, in an attempt to
artificially create this vorticity, some hastily made vortex generating tabs
were inserted into the turn at the end of test section 4. This technique was
not completely successful, but did indicate that the problem could be solved
with further testing and minor equipment changes.
2.6 CONCLUSIONS
Basically, the velocity profiles of the Particulate Aerodynamic Test
Facility show good quality flow and should provide the basis for many inter-
esting experiments in the particulate flow research. Good quality flow is
available in all but the last test section, and tests can be run in either
uniform or shear flows.
The solution to the problem of poor flow quality in the last test
section could be approached in a number of ways. The method that is most
direct and has the greatest probability of success with minimum expenditure
of time and money is to install one or more turning vanes in the turn. Other
methods would include experimenting further with the installation of vortex
generators or swirl generators in the turn to redirect the higher energy flow
into the "stalled" regions. More elaborate methods might include boundary
layer suction on the inside turn radius of the elbow.
102
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SECTION 3
SUBTASKS 2 and 3: PARTICULATES TESTING
AND ISOKINETIC SAMPLER COMPARISONS
3.1 OBJECTIVES
The objective of subtask 2 was to first document the concentration pro-
files that were being obtained with the aerosol generation system as it was
initially installed*, and secondly, modify the system as required to obtain
dust concentration profiles as uniform and repeatable as possible for use in
reaching the objectives of subtask 3.
Subtask 3 has the primary objective of obtaining comparative test data
between a commercially available low volume "Method 5" isokinetic stack sam-
pler and a newly developed high volume isokinetic sampling train. The low
volume unit was typical of most currently available mass sampling systems
which sample at rates less than one CFM. The primary drawback of these low
volume sampling rate devices is that, in regions of low particulate loading,
they necessitate excessively long sampling periods in order to gather mea-
surably significant quantities of pollutants and thus achieve acceptable
accuracy. As a consequence of these long sampling cycles, short term oper-
ating conditions, which can vary widely during the sampling process, can be
completely masked.
A secondary objective of subtask 3 was to demonstrate the utility of
the recently completed Particulate Aerodynamic Test Facility in simulating
repeatably, on a steady state basis, a condition or range of conditions typi-
cal of industry stack sampling environments.
3.2 THE APPROACH
The approach to accomplishing subtask 2 was to make horizontal tra-
verses with the sampling probe of a direct-reading (IKOR) dust sampler at
various test sections to determine the kind of profiles being obtained with
a given aerosol generatory test set-up. The most important variable in
An interim system, pending the design and installation of more sophistica-
tion and higher mass flow rate.
103
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adjusting the dust profiles was, of course, the location of the injector
lines themselves.
Objective 3 was achieved by injecting dust and simultaneously sampling
a given axial location by the two sampling devices to be compared. Concen-
trations during the tests were monitored for constancy on a real time basis
by the direct reading sampler located downstream. Figure 29 shows the basic
test arrangement.
3.3 TEST APPARATUS
The test apparatus for subtasks 2 and 3 consisted of:
Aerosol generation system
Real-time concentration monitor:
IKOR Model 206 Portable Air Quality Monitor
Low volume sampler:
Lear Siegler Model 31 Stack Sampler
High volume sampler:
Aerotherm High Volume Stack Sampler
The final configuration of the aerosol generation system is shown
pictorally in Figure 30. The system consists of six major components:
Pressurized storage/feed bin
Modified Acrison Model 120-0 screw feeder
Aerosolization chamber
Transport line
Distributor
Injection tubes
The aerosolization chamber may be roughly characterized as a fluidized
bed, but it should be pointed out that high quality fluidization is not gen-
erally attained due to the agglomerated condition of the dust and the rela-
tively high superficial air velocities through the chamber. The incoming
dust, the bulk of which is highly agglomerated and too heavy to be entrained
in the air flow through the chamber directly, drops down to a churning bed of
dust where it is broken up and de-agglomerated to the point where it may be
carried away to the tunnel. Further dispersion is accomplished by impact and
shear forces as the dust is transported at high velocity to the tunnel.
104
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o
en
COWTEACTIOM SECTION*
TEST SEOTIOM
TVPiCAL. 4- PLACES
Figure 29. Basic Task 3 Test Arrangement
-------
so.
106
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Actual redispersion and de-agglomerization efficiency was not of im-
portance in these subtasks, and consequently was not determined quanitatively.
Qualitatively (by visual observation) however, the de-agglomeration appeared
to be excellent.
Feed rate control was achieved with an Acrison screw feeder modified
by installation of a cylindrical bin which is pressurized at the same pres-
sure as in the aerosolization chamber. Pressurization was necessary because
the screw feeder was not designed to feed against pressure.
The transport line was 3/4 inch vinyl tubing. The distributor split
the aerosol flow from the transport line into eight individual injection
lines which were routed through the stilling chamber straightening vanes to
appropriate injection points.
The real time concentration monitor was an IKOR Model 206 Portable Air
Quality Monitor. A sample is continuously drawn through an electronic sensing
head where the particulates generate an electric current by charge transfer.
This feature, combined with a strip recorder output, allowed continous real-
time monitoring of any point of interest and relatively rapid traverses of
the tunnel duct to be made to obtain concentration profiles. The features
and dimensions of the unit are given in Table 1.
TABLE 1
MODEL 206 PORTABLE AIR QUALITY MONITOR
IKOR INCORPORATED
BURLINGTON, MASSACHUSETTS
1. Weight and Dimensions
a. Stack Unit 18 x 11 x 17 25 Ibs
b. Control Unit 26 x 11 x 20 28 Ibs
c. Stack Probe 5 ft length 13 Ibs
2. Participate Emission Mass Flow Range, 0.001 - 100 Grains/SCF
3. Particulate Size Detection, 0.1 - 100 microns
4. Stack Temperature Range, 30ฐF - 2000ฐF
5. Ambient Operating Temperature Range, -20ฐF - +160ฐF
The two manual samplers to be compared were basically equivalent sampler units
(except for sampling' rate and certain commercial features) based on EPA Method
5 particulate sampling technique. The low volume sampler was a Lear Siegler
Model 31 Manual Stack Sampler, and the high volume was an Aerotherm HVSS Stack
Sampler.
107
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3.4 TEST PROGRAM AND RESULTS
The test program consisted of setting up the tunnel flow environment
to simulate conditions typical of stack environments. The parameters se-
lected were:
Air as the gas stream
Temperature: 300ฐF
Velocity: 60 fps
Dust concentration: approximately 0.5 grains/cu.ft.
Profiles were taken horizontally with the IKOR sampler at various sta-
tions. The data was automatically recorded on a strip chart recorder in real
time. The data presented in this report is replotted from these strip chart
records for clarity.
The initial injection line arrangement was as shown in Figure 31. The
eight injection lines were equidistant from one another on a circle of ap-
proximately 40 inches diameter. The plane of injection was approximately 4
feet forward of the wind tunnel straightening vanes - essentially at the en-
trance of the contraction. These positions correspond to those originally
designed into the tunnel.
Typical profiles obtained by this arrangement are shown in Figure 32
which shows max-min data from traverses at test sections 2 and 4. The data
shows a fairly high degree of scatter and extremely nonuniforn profile (de-
finite injector "spikes") at station 2; by test section 4, however, enough
mixing has occurred that the profile is more uniform bell shape, as would be
expected, and with less data scatter between max-min points.
The effect of velocity was explored in this same configuration; the
results are shown in Figure 33, which presents the data from traverses at
test section 4 at three different velocities. It demonstrates that at the
higher velocities, the dust tends to migrate more toward the center to cause
a steeper concentration gradient across the duct. This is probably attribu-
table to the imbalance of aerodynamic forces acting on the particles in a
nonuniform velocity field; in other words "lift" towards the center of the
duct is being generating on the particles.
To obtain more uniform profiles across the duct for the entire length
of the tunnel test section, the injection line arrangement was modified to
that shown in Figure 34. This was necessary to provide a more reliable basis
for the comparison tests of subtask 3. The plane of injection in this case
108
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o
vo
(o FT Dl* STILLING, CHAMBER
2. FT Dlfc TEST SECTION
F\JXM& OF
INJECTDI2. LCXA710MS
40 IM. INJECTION
CIECL&
Figure 31. Initial Injection Line Arrangement
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- DUST
TUNNJ&J --
TEST SECTION VELOC.ITV &O FRS
A TEST SECTION!
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DU5JT PBDFILES-DORSeV
TEST ^gCTlON VELOGTrY 0 90 FP&
A&OFPS ~
30 FPS
SECTION 4
TUMMEL.
Figure 33.
Ill
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FT DI/X STILUNq CHAMBER
20 IN. INKJET
INJECTION DI/XMETE2
ro
FLAME. OF INJECTION
INJECTION DIAMETE/2.
Figure 34. Final Injection Line Arrangement
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was 2 inches forward of the straightening vanes. Figure 35 shows the profile
that resulted from this arrangement after final tuning of the injection lines
to achieve near equal distribution of the dust between them. The profile is
relatively flat and exhibited only a ฑ10 percent concentration variation;
time-averaged over a few minutes these fuctuations were of negligible im-
portance .
The two samplers were placed in test section 2 from opposing sides at
approximately equal concentration points. Test durations of 4 hours for the
low volume sampler and 1 hour for the high volume sampler were selected for
the data comparisons. Even with this 1 to 4 time ratio, the total sample
volume ratio was 2 to 1 in favor of the high volume sampler because of its
8 to 1 sampling rate ratio over the low volume sampler. This meant that
allowing for wind tunnel and aerosol generater set-up time each day, it was
possible to obtain only one sampler per day with the low volume sampler and
as many as 3 5o 5 per day with the high volume sampler. In addition sample
twice the volume of particulate-laden flow in any given test.
Table 2 presents the data of three days of testing. The concentrations
measured by both samplers are in close agreement in each case; averages over
the three days are exactly the same. Because of its capability for higher
sampling rate, however, the high volume sampler was able to detect slight
variations in concentration that could not have been detected by the low
volume sampler.
Another test result of interest is that a negligible amount of parti-
culates settled in the probe of the high volume sampler. The high velocity
in the probe assures that nearly all the sample is carried into the cyclone
or filter; accuracy is enhanced.
3.5 CONCLUSIONS
The present aerosol generation system can deliver a range of dust con-
centrations with a variety of profiles, depending on placement of injection
lines. The system exhibits good de-agglomeration efficiency and provides
reasonably long term operation with constancy of output. At present, however,
the system is capable of only a few hours operation without shut-down to re-
plenish the bin (1 cu.ft.). This capability is soon to be extended under
another program.
High volume sampling trains were demonstrated to be superior to low
volume sampling trains for at least three reasons:
113
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\0
I
i.
8
b
3
0
111
I
u
I
n.5>
CEDSS-SECTIOM
Figure 35. Final Concentration Profile for Subtask 3
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TABLE 2
Date
3-18
3-19
3-20
Low Volume
Time
10:53
14:53
10:30
14:45
9:22
13:22
Vol ume
(scf)
128.7
136.4
128.5
Cone.
(gr/scf)
0.045
0.038
0.038
Average 0.040
High Volume
Time
11:30
12:30
13:45
14:45
10:30
11:30
13:15
14:15
9:30
10:30
11:02
12:02
13:00
14:00
Vol ume
(scf)
232.7
236.4
Avg.
238.4
240.5
Avg.
231.8
231.7
236.8
Avg.
Cone.
(gr/scf)
0.047
0.046
0.0465
0.043
0.035
0.039
0.036
0.039
0.032
0.036
0.040
115
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Sampling time is reduced for equivalent volume sample. This means
reduced time investment in the sampling task.
More samples/day on short turn-around are possible. This means it
is possible to detect variation of short duration during a typical
8 hour testing period.
Negligible sample loss due to settling in the probe. This means
increased accuracy.
116
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TECHNICAL REPORT DATA
fPlceir read Inunctions on iht rtvmt before completing)
i REPORT NO
EPA-650/2-74-103
3 RECIPIENT'S ACCESSION NO.
4 TITLE AND SUBTITLE
Design, Fabrication, and Installation of a Particulate
Aerodynamic Test Facility
6 REPORT DATE
October 1974
6 PERFORMING ORGANIZATION CODE
7 AUTHOR1S)
Dale D. Blann, Ken A. Green, and
Larry W. Anderson
8 PERFORMING ORGANIZATION REPORT NO
74-108
9 PERFORMING OR9ANIZATION NAME AND ADDRESS
Aerotherm/Acurex Corporation
485 Clyde Avenue
Mountain View, California 94040
10 PROGRAM ELEMENT NO.
LAB012; ROAP 21ADJ-080
11. CONTRACT/GRANT NO.
68-02-0625
12 SPONSORING AGENCY NAME AND ADDRESS
EPA, Office of Research and Development
NERC-RTP, Control Systems Laboratory
Research Triangle Park, NC 27711
13. TYPE OF REPORT AND PERIOD COVERED
Final; Through 7/25/74
14 SPONSORING AGENCY CODE
15 SUPPLEMENTARY NOTES
16. ABSTRACT
The report presents the trade-offs and design considerations, component selection
criteria, and final design details for a particulate aerodynamic test facility. The
design meets a range of performance specifications for the test gas, including
test section gas velocities to 90 ft/sec, temperatures to 450F, and variable humidity
and gas composition, including particulates.
7.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS C. COSATI Field/Group
Air Pollution
Aerodynamics
Test Facilities
Wind Tunnels
Design Criteria
Fabrication
Installing
Air Pollution Control
Stationary Sources
Particulates
13B
20D
14B
14A
13H
8. DISTRIBUTION STATEMENT
Unlimited
19 SECURITY CLASS (This Report)
Unclassified
21. NO. OF PAGES
122
20 SECURITY CLASS (Thispage)
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
117
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