EPA-650/2-73-028
September 1973
ENVIRONMENTAL PROTECTION TECHNOLOGY SERIES
1
I
-------
EPA-650/2-73-028
ENCLOSED COKE PUSHING
AND QUENCHING SYSTEM
DESIGN MANUAL
by
D.A. Pengidore
National Steel Corporation, Weirton Steel Division
P.O. Box 431
Weirton, West Virginia 26062
Contract No. 68-02-0622
Program Element No. 1AB013
EPA Project Officer: R.C. McCrillis
Control Systems Laboratory
National Environmental Research Center
Research Triangle Park, N.C. 27711
Prepared for
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D . C. 20460
September 1973
-------
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.
ii
-------
ABSTRACT
The Weirton Steel Division of National Steel Corporation has contracted
with Koppers Company to design and construct a new coke plant consisting
of a single battery of 87 ovens and complete coal chemical plant and
support facilities. The coke ovens are of the new tall oven configura-
tion and the plant features the most advanced production techniques and
air and water pollution control devices which set a new benchmark for
modern coking operations.
A most significant feature of this new plant involves the development of
a new concept in abating the air pollution normally associated with the
pushing and quenching emissions. Koppers Company with the Weirton Steel
Division and with the support and cooperation of the Environmental
Protection Agency has designed and constructed an "Enclosed Coke
Pushing and Quenching System."
The concept of this new system involves the containment of the hot coke
from the face of the slot type oven during the pushing operation,
through the successive handling and transport, and through a continuous
and controlled quench. The hot coke emissions are confined and cleaned
before discharge to the atmosphere and the quench emissions are controlled
to stack discharge of low velocity steam vapor.
This report was submitted in fulfillment of Contract No. 68-02-0622 by
National Steel Corporation, Weirton Steel Division, under the partial
sponsorship of the Environmental Protection Agency. Work was completed
on June 30, 1973.
iii
-------
ACKNOWLEDGMENTS
The following personnel and organizations are recognized with apprecia-
tion for their contribution and assistance in preparation of this
Design Manual:
Mr. D. A. Pengidore
Project Director
Weirton Steel Division
National Steel Corporation
Mr. A. Fraser
Assistant Project Director,
Engineering
Weirton Steel Division
National Steel Corporation
Mr. H. Wood
Assistant Project Director,
Environmental
Weirton Steel Division
National Steel Corporation
Mr. W. D. Edgar
Manager Pollution Control Projects
Koppers Company
Mr. R. C. McCrillis
Project Officer
Control Systems Laboratory
Environmental Protection Agency
iv
-------
CONTENTS
PAGE NO.
Abstract iii
Acknowledgments iv
List of Figures vi
List of Tables vii
Sections
I Conclusions 1
II Introduction 3
III Process Description 7
IV Process Design 15
V Environmental Posture 57
VI Capital Cost Estimates 63
VII Operating Cost Estimates 67
VIII Start Up Experience to June 30, 1973 81
IX Units of Measure - Conversions 85
-------
FIGURES
FIGURE NO.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
DESCRIPTION
System General Arrangement
Flow Diagram #1
Flow Diagram #2
Instrument Flow Diagram
System General Arrangement
(with legend)
Coke Guide Hood General Arrangement
Hot Coke Transfer Car General
Arrangement
Gas Cleaning Car General Arrangement
Quenching Pit General Arrangement
Quenching Pit - Section A-A
Quenching Pit - Section B-B
Quenching Pit - Section C-C
Quenching Pit - Section D-D
Quenching Pit - Section E-E & F-F
Emergency Dump Pit General Arrangement
Coke Quenching Car Alterations
Emergency Quenching Station Sections
Manual Coke Wharf
Substation and Electrical Control
Room General Arrangement
Control Room Instrument Panel
General Arrangement
PAGE NO
5/6
9/10
11/12
13/14
29/30
31/32
33/34
35/36
37/38
39/40
41/42
43/44
45/46
47/48
49/50
51/52
53/54
55/56
77/78
79/80
vi
-------
TABLES
TABLE NO. DESCRIPTION PAGE NO.
1 Comparison of Quench System
Service Water 60
Comparison of Environmental
Posture 62
Estimated Operating Cost Comparison
on a Man-hour per Week Basis 70
Estimated Operating Cost Comparison
on a Man-hour per Ton of Coke Basis 72
Electrical Comparison Connected
Horsepower of Major Facilities 74
vii
-------
SECTION I
CONCLUSIONS
The overall goal in preparation of this report is to demonstrate
a system designed for emission control capability, operability,
reliability and maintainability. This report covers only
Phase 1 relative to the Enclosed Coke Pushing and Quenching System
and involves the design and construction of the system.
The final report in this program will be issued at the conclusion
of Phase 2, Emission Testing and System Evaluation Program. Phase 2
will concern itself primarily with the degree to which the system
goals were attained. As this report anticipates the operation of
the system, it is not possible to draw conclusions at this time.
-------
-------
SECTION II
INTRODUCTION
The new 87 oven Koppers1 twin-flue battery for the Browns Island
plant of Weirton Steel will have a coke production rate of about
150 tons* per hour, while operating at a gross coking time of 15.4
hours. Modern pollution control equipment is being incorporated
throughout this new plant and a totally new concept for the control
of oven pushing and quenching emissions has been developed. This
concept includes the total enclosure of the coke during the push and
during the transfer period to the quenching system. Scrubbers are
used to remove particulate matter throughout the operation and the
intermittent large quenching vapor cloud, characteristic of all coke
plants, has been reduced to a smaller continuously flowing plume of
water vapor.
Full enclosure of the push has been made by the use of a hood which
surrounds the coke guide and which makes a tight connection to a
single position hot coke transfer car. Other coke plants rely upon
the motion of the quench car during the push to spread the coke to a
uniform depth for proper quenching, but with this system the car is
sized so that the coke is pushing without moving the transfer car.
Quenching of the coke is achieved by emptying the coke from the
transfer car into one of three receiving hoppers, from which the coke
* A list of factors for converting from non-metric to metric units is
provided on page 84.
-------
is fed by vibrating feeders onto the vibrating quenching conveyors.
Greater control of coke moistures is to be expected because of the
thinner depth of coke at quenching and because of better control of
quenching water volumes. Clean water is provided as makeup to the
quenching and gas cleaning systems. The water system is closed and
completely recirculating.
Figure 1, System General Arrangement (drawing #319-A600), illustrates
the various components incorporated into this new system, their
interaction with each other, and with the coke oven battery proper.
(The components are identified in Figure 5.)
-------
PAGE NOT
AVAILABLE
DIGITALLY
-------
SECTION III
PROCESS DESCRIPTION
Figures 2 and 3 (drawings #319-A616 and #319-A617) describe the
conditions of transfer of hot coke from the oven through the quenching
operation. The diagrams also provide information on design parameters
used in the processing of the gas streams through the venturi scrubbers,
quench steam to the stack, and the water spray services. Figure 4
(drawing #319-A618) is an instrumentation flow diagram with complete
information on the monitoring and control of the process as conceived
for this particular design.
The flow diagrams indicate the general application and use of water in
the quench system. General service water is the source of makeup to
the system and is used in a number of once through applications with
subsequent discharge to recirculation sump. A direct service water
makeup to the sump provides the makeup trim source necessary to maintain
sump level control.
The venturi scrubbers, the stack mist suppressor, certain duct sprays,
and the track hopper sprays all use service water as their primary
source. The waters not vaporized in these services are ultimately
returned to the quench sump.
The primary use of recirculated water is in direct spray application
to the incandescent coke and for conveyor belt protection responding
to temperature monitoring.
-------
The gas flow definition as presented in Figure 2 represents the fume
and steam flow quantities at the maximum levels. The quench steam
discharge is based on the normal operating mode of two (2) quench
units operating concurrently. The fume system discharge represents
the condition when one (1) hopper is being charged and the maximum
fan capacity is being utilized. The gas flows and particulate
loadings are design values; they are not a result of measurements.
Establishing the exact values will be one of the principal goals of
Phase 2 of the demonstration.
-------
PAGE NOT
AVAILABLE
DIGITALLY
-------
SECTION IV
PROCESS DESIGN
This section provides definition of the various major components
contributing to the system as defined in Figure 5 (drawing #319-A600).
A. DOOR MACHINE
Each door machine is of the standard design with a door extractor,
door and jamb cleaners, and the necessary electrical controls for
all operations, including the coke guide. The traction drive for
the door machine - coke guide unit is also a part of the door
machine.
B. COKE GUIDE (Figure 6, drawing #319-A601)
The coke guide car consists of two connected sections. The first
section is the coke guide rack which is similar to the standard
design except that it has been totally enclosed and fits tightly
againt the buckstays and against the top of the jamb casting.
With this tight enclosure, no smoke will escape from the oven
door opening or from the guide during a push.
The second section of the coke guide is the hood. It is a double
segmented, quandrant type shroud with a rectangular cross section.
This shroud is mounted on the front steelwork of the coke guide
frame to totally enclose the push and contain the smoke during
the push. The stationary section of the hood is attached to the
fixed frame of the coke guide; the movable segment pivots
from this frame to contact the raised section of the hot coke
15
-------
B. COKE GUIDE (Figure 6) - Continued
transfer car. Structural steel members of both segments are
protected from the heat by stainless steel plates which also
form the hood enclosure. These plates are loosely bolted to
the structural frame. Seal plates are provided to cover the
gaps between the fixed and movable sections of the hood.
After the door has been removed, the coke guide is positioned
in front of the oven to be pushed by the door machine operator.
The guide is then racked in to give support to the coke during
the push. When the hot coke transfer car has been properly
spotted, the movable hood is lowered onto the raised section of
the coke transfer car. This lowering action prevents the car
from traveling and prevents the coke receiving car's sealing
curtain from closing. The cross-battery interlock circuit is then
energized permitting the push to occur.
After the pusher ram has been retracted, the door machine operator
raises the fume hood and the traction drive interlock for the hot
coke transfer car is released.
C. HOT COKE TRANSFER CAR (Figure 7, drawing #319-A602)
The hot coke transfer car is a four-axle type car with a fabricated
structural steel frame supporting one large hopper which is capable
of handling one oven of coke in a single position. The hopper is
totally enclosed including a scalable opening which is raised and
16
-------
C. HOT COKE TRANSFER CAR (Figure 7) - Continued
canted toward the oven to meet the extendable hood segment of the
coke guide. Also, there is a flexible stainless steel retractable
sealing curtain which closes over the opening during the travel
period. This curtain is driven by pushbutton from the cab of the
gas cleaning car.
The enclosed hopper consists of structural steel and plate
weldments with an internal lining of high duty refactory fire
brick. Hinged hopper gates for the discharge opening in the
bottom of the hopper are pneumatically operated from the locomotive
cab. When the gates are opened, the car cannot travel. The gates
open downward and out to provide a nearly total enclosure with the
top of the individual track hopper.
To position the hot coke transfer car at the oven, the operator
moves to an approximate location where lights will indicate
whether the transfer car is either right or left of the receiving
position. The operator then moves the transfer car as needed to
complete this pushing interlock where a third light indicates that
the car is centered. Once the car is spotted the sealing curtain
is opened and the coke guide hood is lowered.
D. GAS CLEANING CAR (Figure 8, drawing #319-A603)
The gas cleaning car is composed of two sections: the operator's
cab and locomotive and the gas cleaning system. From the operator's
17
-------
D. GAS CLEANING CAR (Figure 8) - Continued
cab, the operator can move the gas cleaning car and the hot coke
transfer car unit, and control the transfer car curtain dump
gates, and the gas cleaning equipment.
The scrubbing system which is mounted on the gas cleaning car
consists of spray nozzles for cooling the hot gases in the duct
from the hot coke transfer car and a high energy variable throat
venturi scrubber. The gas passes through the high energy venturi
scrubber, the flooded elbow, the cyclonic separator, and finally
through the fan and out the exhaust stack. Contaminated water from
the scrubbing system is returned to the main recirculating water
sump and is periodically replenished from a fixed source by the
car operator.
The gas cleaning system has been sized conservatively by selection
of the largest fan drive that can be reasonably supported by the
collector rail system (400 HP). The prediction of actual
particulate loading during the coke pushing operation contains
many variables and involves the potential for abnormal operating
conditions including partially carbonized coal in the push. It
is anticipated that the system as furnished will provide some
margin of capacity to effectively clean the gases evolving from
abnormal operating conditions.
The suction fan is equipped with a two (2) position inlet louver
control and the venturi throat is automatically operated to two (2)
18
-------
D. GAS CLEANING CAR (Figure 8) - Continued
positions. Both of these operations are pneumatically controlled.
this provides two (2) modes of gas cleaning operation. During
startup and during the coke transport period the venturi is in a
full open position and the fan inlet louvers are restricted. The
drop across the venturi in this mode should be 10" w.c. or less.
While in the coke receiving and discharge operations, the venturi
is moved to its most restrictive position and the fan inlet is full
open. A maximum drop across the venturi of approximately 35" w.c.
is anticipated during this mode.
The referenced drawing indicates clearances between the gas
cleaning car and the coke guide hood and door machine that are far
more critical than any imposed by the use of the conventional quench-
ing equipment. Track alignment becomes critical under these new
conditions and of necessity tracks must be supported on firm and
predictable foundations. Maintenance attention will be required to
assure track and car conditions consistent with these clearances.
E. TRACK RECEIVING HOPPER (Figures 9 through 14)
Three coke receiving hoppers are located at the quenching station
beneath the quenching track for receiving incandescent coke from
the hot coke transfer car. Each of the three hoppers can hold
one oven of coke although normally two hoppers will be used with
the third available as a spare. Each hopper is formed of steel
19
-------
E. TRACK RECEIVING HOPPER (Figures 9 through 14) - Continued
plate and lined with refractory brick and has a charging hole
3 ft - 6 in by 14 ft in the top. This rectangular opening
is slightly larger than the opening in the hot coke transfer
car to facilitate discharging. Hinged gates for the track hopper
top openings are provided to prevent gas escape between the dis-
charges of coke from the car. Each set of gates is operated by
a shaft and lever system powered by a pneumatic cylinder. An
interlock timer for each hopper's gates prevents the coke from
being dumped into the same hopper until a preset time has elapsed
permitting the hopper to empty. Also, a red light at the dump
area for each hopper indicates to the operator that he should
travel to the other available hopper if the full time has not
elapsed. The top hinged gates of the hoppers open upon a signal
from the gas cleaning car cab console, provided the hopper runout
time has elapsed. When the gas cleaning car operator causes the
hot coke transfer car gates to start to close after dumping the
coke, the receiving hopper gates begin to close, and then the fume
exhaust main suction bypass duct butterfly valve closes causing all
fumes from the hopper to pass through the fume combustion system.
Near the top of each hopper a refractory castable-line offtake duct
withdraws fumes from the hot coke in the hopper. In each duct as
well as at the top of each hopper are water sprays to reduce the
temperature of these fumes. The withdrawn gases are sent by way of
20
-------
E. TRACK RECEIVING HOPPER (Figures 9 through 14) - Continued
this duct to the fume combustion chamber which is described in
Section H.
Each hopper has a working capacity for one load of coke from the
hot coke transfer car. Since it requires approximately 18 minutes
to discharge one hopper of coke to its quench system, it becomes
necessary to drop the second load of incandescent coke into the
other operating hopper (or the third hopper in an emergency).
On the bottom of each coke receiving hopper is a pneumatic
vibrating feeder which controls the rate at which the hot coke is
discharged onto the vibrating quench conveyor train. Maximum hot
coke feed rate is 85 TPH; normal rate is 80 TPH based on a 15.4
hour gross coking time.
F. COKE HANDLING (Figures 9 through 14)
Vibrating quench conveyors receive the hot coke from the vibrating
feeders. There is one fixed speed vibrating quench conveyor per
coke receiving hopper, having a roughened surface which promotes
coke conveying. Along the vibrating conveyor pans, from the
receiving hopper to the M-l conveyor belt, cooling sprays are
directed upon the passing coke.
The M-l conveyor belt transports the coke from the vibrating
conveyors to a junction point just below yard level where it
21
-------
F. COKE HANDLING (Figures 9 through 14) - Continued
discharges onto the M-2 conveyor belt. The M-2 conveyor belt
carries the coke to the top of the loadout bin. These conveyor
belts are also interlocked to prevent M-l from running if M-2
is stopped and M-2 cannot be run if the loadout bin is full.
M-4 conveyor belt from the emergency coke wharf also feeds onto
M-2 at the junction point.
The 150 ton capacity quenched coke loadout bin has a double gated
discharge at the bottom. High level probes at the top of the
bin control the coke conveyor belt to prevent overloading of the
bin. A coke bypass flop gate can be operated in case the bin
becomes full, whereby the coke is discharged from M-2 conveyor
across the flop gate into a discharge chute to the ground. Normally,
the coke from the storage bin will be loaded into trucks. The truck
operator will be able to observe and control the coke loading proce-
dure from the cab of his truck through the use of a television
monitor and a carrier type transmitter and receiver for operation of
the hopper gate. In order to minimize the fugitive dust from the
coke handling system, a dust collector as well as a vacuum cleaning
system are provided.
22
-------
G. SPRAY WATER AND STEAM EXHAUST SYSTEMS (Figures 9 through 14)
In order to cool the hot coke, water is sprayed on the coke at a
controlled rate by five banks of sprays which are located along
the sections of each vibrating conveyor. The tumbling action and
movements of the coke in the water bed causes maximum water-coke
contact, especially by the first four banks of sprays that are
activated by the operation. These four are operating while hot
coke is being conveyed and the fifth bank at the discharge end
comes on only when a high coke temperature is sensed after the
fourth spray bank.
The runoff water is collected in a floor channel and returned to
a settling basin. In the settling basin the water and solids
separate, with the clarified water flowing over a weir into the
clear well where it is recirculated by one of two pumps to the
sprays over the vibrating conveyors or to the M-l conveyor belt
in conjunction with another hot coke sensor. The solids which are
collected in the settling basin fall to the bottom where they are
pumped out by a sludge pump either onto the cool end of one of the
vibrating conveyors or into a container at yard level. If the spray
water pumps at the clear well fail, an emergency water tank located
above ground contains sufficient water to quench any coke remaining
in the track hoppers and on the vibrating conveyors. This emergency
system is controlled by the quenching station operator who is warned
of water failure by appropriate alarms.
23
-------
G. SPRAY WATER AND STEAM EXHAUST SYSTEMS (Figures 9 through 14)-Continued
Makeup water to the spray water system is supplied from the general
service source. Because this is a closed recirculating water
system, only makeup water is added to compensate for steam losses
and no water is discharged from the system.
Each coke quenching conveyor system has an exhaust hood enclosure
constructed of removable stainless steel panels, with access doors
for inspection of the vibrating conveyor pans and the sprays. At
the top of each flared hood is an exhaust duct which contains an
axial type fan for positive steam withdrawal. The steam is discharged
into an exhaust duct which conducts it into the exhaust stack. A
wooden louver mist suppressor is provided inside the stack to remove
the entrained water and particulate matter. Water sprays are located
above the suppressor to backwash the baffles.
After a short time delay, a spray in the duct near the exhaust fan
comes on whenever the exhaust fan is operating to cool the gas and
the fan drive system.
H. TRACK HOPPER FUME EXHAUST AND GAS CLEANING SYSTEM (Figures 9 through 14)
At the top of each receiving hopper is an exhaust duct which is
independent of the steam withdrawal system. This duct consists
of two sections, one for fumes and combustion gases from the
incandescent coke in the hopper and the other for the initial
coke dumping period when both ducts are used for handling the
24
-------
H. TRACK HOPPER FUME EXHAUST AND GAS CLEANING SYSTEM
(Figures 9 through 14) - Continued
large volume of air and gas which is generated (Figures 10 and
14). This large volume comes from the quick displacement of
air by the coke dropping into the hopper as well as from the
burning of the incandescent coke while falling. It is
therefore necessary to use the auxiliary suction duct to with-
draw this large volume until the coke has been dumped and the
receiving hopper top gates have been closed. This is, of course,
a short interval (10 to 20 sec.) relative to the residence time
of the coke within the hopper.
After the hopper gates have been closed, the butterfly valve in
the secondary duct closes causing a reduction in volume of
offtake gas, but the suction is sufficient to handle the gas
generated. The suction from the fan pulls the gas from the
hopper through the fume burner duct only. In the fume burner
duct, an air admission port is provided along with a coke gas
fired pilot burner to initiate combustion of any combustible
gases that may be generated. There is also a cooling spray
beyond the fume burner which is actuated by high gas temperature.
After the gases pass through the burner section of the duct, they
continue through a high energy type scrubber, across a flooded
elbow which separates the heavier particulate matter from the gas
stream, through the cyclonic moisture separator, and through a
centrifugal type exhaust fan (which pulls the suction on the coke
25
-------
H. TRACK HOPPER FUME EXHAUST AND GAS CLEANING SYSTEM
(Figures 9 through 14) - Continued
receiving hoppers) before being discharged as cleaned gas into
the stack (Figure 9). The dirty water from the flooded elbow
is returned to the settling basin described in Section G.
The collected water from the cyclonic separator drains into a
seal pot which overflows into a channel that also runs to the
settling basin.
I. EMERGENCY COKE DUMP PIT (Figure 15, drawing #319-A610)
On the north side of the continuous quenching system is an
emergency coke dump pit. This is used only when the continuous
quenching system is inoperable and the hot coke transfer car
contains a load of incandescent coke which must be dumped.
When this condition is encountered the transfer car passes
through the track hopper area to the emergency dump station.
The car is manually positioned over the pit which has reinforced
concrete sides with a firebrick lining and is capable of holding
one load of coke. It is open on the east side with a concrete
approach ramp so that the coke may be removed by a front-end
loader. There is a spotting interlock which must be satisfied
in order to open the coke car gates.
To cool the hot coke, three banks of sprays are located at the
top of the pit, with five sprays per header. A manual shut off
valve which regulates the mill water to the sprays is located
26
-------
I. EMERGENCY COKE DUMP PIT (Figure 15) - Continued
adjacent to the pit. The car operator dumps the load of coke
into the pit, leaves the car and goes to the valve station
where the water valve for quenching the coke is opened for the
required time and is then closed. Thereafter the standard coke
quenching car must be employed until the continuous quench system
is in operation again.
The run-off from the emergency quench is collected in a sump and
is discharged into the quench track drainage trench which runs
back to the sump in the continuous quench station pit.
J. EMERGENCY POKE QUENCHING SYSTEM AND WHARF (Figures 16 through 18)
In case of an extended downtime at the continuous coke quenching
station an emergency quenching station is available at the south
end of the battery. The regular enclosed coke transfer car is
not adaptable to the conventional quenching system; therefore, a
standard 40 foot quench car with a sloped bed (Figure 16, drawing
#319-A612) is employed using a trackmobile as the method of
moving the coke car. The trackmobile also serves for other
emergency needs when not needed for quenching.
The quenching station is located at the south end of the battery
and the emergency coke wharf is located midway between the station
and the continuous quenching site. The quenching station (Figure 17,
drawing #319-A611) is an open type with overhead sprays which are
27
-------
J. EMERGENCY COKE QUENCHING SYSTEM AND WHARF
(Figures 16 through 18) - Continued
operated from a control room by the car operator. The dirty water
is collected in a sump and pumped to a trench which drains to the
main sump at the continuous quenching pit.
After the coke has been quenched, the trackmobile pulls the
quenching car to the emergency coke wharf (Figure 18, drawing
#319-A615) where the coke is dumped. The coke is fed onto a
conveyor belt (M-3) by an operator using manual wharf gates.
The coke is transferred from M-3 conveyor to M-4 conveyor and
then to M-2 conveyor which leads to the loadout bin.
K. DESIGN COMMENTARY
The design and equipment scope for this particular project is
being developed in very conservative terms. Since the reliability
of performance of certain of the equipment and the system in
general has not been established in actual operation, the owner
has elected to provide operational spares for all critical
components and has also provided complete, although limited, con-
ventional quenching capability as backup protection. It is entirely
possible that performance experience will permit reduction or elimi-
nation of certain of those facilities on subsequent installations.
28
-------
PAGE NOT
AVAILABLE
DIGITALLY
-------
SECTION V
ENVIRONMENTAL POSTURE
The design concepts introduced with this new system were developed
for the express purpose of eliminating the air pollution conditions
inherent in the handling of incandescent coke from the ovens through
the quenching operation.
The conventional system, currently in use throughout the industry,
involves pushing hot coke from the ovens through a guide into an
open, shallow-bed car for transport to a batch type quenching
station. Substantial emissions of smoke and particulate are dis-
charged into the atmosphere during the period when the coke passes
through the guide, when the coke breaks up leaving the guide, and
during the distribution of coke into the quench car. The quantity
of the emissions encountered during this phase of the operation and
in the subsequent transport is affected by the completeness or
efficiency of the coking process within that particular oven. If
the push contains coke that is not completely carbonized, the com-
bustion of the volatile matter will cause smoke emission from the time
of exposure until it is water quenched.
The conventional quenching station involves the introduction of large
quantities of water distributed over the bed of hot coke. The forma-
tion of steam and vapor is almost explosive in nature during the
initial phase of this quench procedure. This large volume of steam
is discharged at relatively high velocity from an appropriate stack
57
-------
or tower. This condition creates a situation in which large
quantities of steam and entrained moisture are discharged into
the atmosphere.
This new system offers relief from all of the problem areas
associated with the conventional process techniques.
The coke guide is totally enclosed within a segmental steel hood.
Minimum clearance closure is provided at the interface of the
hood and oven and between the hood and the coke transfer car.
The transfer car is so configurated that it will accept the total
coke push while in this single stationary position. During the coke
push the guide hood and transfer car are under suction to a gas
cleaning car. All emissions generated during this operation are
drawn through a high energy venturi scrubber prior to release to
the atmosphere. At the conclusion of the push, the guide hood is
retracted from the transfer car and a wire mesh sealing curtain is
drawn over the car opening. The car remains under suction to the
scrubber during the entire residence time of the coke. The gas
cleaning car also serves as the locomotive and is coupled to the
transfer car.
The combination of facilities described above eliminates the emissions
problems associated with the push as well as with the transport
interval to the coke quench facility.
58
-------
The continuous quenching facility as conceived for this particular
design involves the use of several underground refractory lined
hoppers. The transfer car is positioned over one of these hoppers.
Pneumatically operated doors on the hopper and on the transfer
car are opened and the hot coke is discharged into the underground
hopper. The doors provide limited exposure of the coke to the
atmosphere during this transfer and during this period the hopper
is under suction to another high energy venturi scrubber. The
hopper remains under the influence of this suction and scrubber
during the entire residence time of the hot coke.
A vibrating feeder at the base of each hopper distributes hot coke
onto a vibrating conveyor at controlled rates. The coke is quenched
by water sprays as it passes the length of the vibrating conveyor.
The quench conveyor is completely hooded and steam generated is
drawn off through a combination of induced and natural draft to a
stack.
The stack provides a common discharge for both the quenching steam
and the scrubber serving the underground hopper. It is anticipated
that the discharge from the stack will be a low velocity, low
volume plume at an almost continuous rate. The stack also contains
a vapor suppressor to further reduce any tendency for carryover.
59
-------
Experimental testing confirmed that 120 gallons of water per ton of
coke is required to quench coke in the manner projected by this new
system. It is anticipated that the system will operate at 10 to 20%
in excess of this requirement.
Conventional quench stations utilize approximately 500 gallons of
water per ton of coke with considerable variation in this quantity
reported by various plant practices.
Table 1 indicates the maximum design ratings of the various service
water commitments to the continuous quench system and to a comparably
sized conventional system. It does not reflect the actual rate of
water consumption.
TABLE 1
COMPARISON OF QUENCH SYSTEM SERVICE WATER
Closed Quench System Conventional
Quench Sump Make-Up 500 gpm 1,250 gpm
Quench Stack Mist Suppressor 400 gpm 650 gpm
(Intermittent Use)
Underground Coke Hoppers 350 gpm
Venturi Scrubber
Gas Cleaning Car 300 gpm
Venturi Scrubber System
The water system is described schematically in Figure 2. The system
is completely closed and the source of makeup water is uncontaminated
service water. Although a direct source of service water capable
of delivering 500 gpm is available at the recirculating water sump and
60
-------
responsive to level control, a major portion of the makeup require-
ments will actually be provided by the gas cleaning systems and other
service water users. The once through waters used continuously at
the stationary gas cleaning system and the intermittent return from
the gas cleaning car venturi scrubber and mist suppressor will
provide the major source of quench water makeup. The coke fines
settled from the recirculating water are periodically pumped to one
of the quench conveyors for removal with the coke. The water flows
as indicated represent capability and do not represent a water balance.
The commitment of gas cleaning and miscellaneous water to quench
system makeup, the capability for close control of coke moisture, and
the substantial reduction in vapor carryover in quench steam are
anticipated to result in a water consumption reduction of approximately
one-third.
Table 2 summarizes the relative position of the new closed coke
quench system to the conventional quench system in terms of resolution
of air and water pollution problems.
As can be seen, the new system offers a solution to all of the current
pollution abatement problems associated with the coke side of the
battery.
61
-------
TABLE 2
COMPARISON OF ENVIRONMENTAL POSTURE
1. Coke pushing
at the
ovens
Closed Coke System
All particulate and fume
contained and scrubbed
prior to discharge
2. Coke transport Coke totally enclosed
to quench with all fumes scrubbed
prior to discharge
3. Coke quenching All fume is contained
and scrubbed in period
Conventional
System
All particulate and
fume discharged
directly to the
atmosphere
All fumes discharged
directly to the
atmosphere. When
green coke is present,
fume discharge is
substantial during
transport
Batch quenching results
in explosive evolution
from transport to quench. and discharge of
4. Water use
Steam generated by
quench is at controlled
rate and at relatively
low velocity when
discharged to atmosphere
No water pollution,
completely
recirculating system
steam, particulate, and
entrained moisture
direct to atmosphere
No water pollution
implication. This
system, too, can be
completely recirculating
62
-------
SECTION VI
CAPITAL COST ESTIMATES
The following cost estimates represent the installed cost of
facilities including engineering, material and labor. They
are considered representative of project costs prevailing to
January, 1973:
1. Enclosed Coke Guide and Telescoping Quadrant Hood
Estimated cost each - $80,600.00
Three (3) units are included in this project $241,800.00
2. Hot Coke Transfer Car
Estimated cost each - $230,700.00
Two (2) units are included in this project $461,400.00
3. Gas Cleaning - Traction Drive Car
Estimated cost each - $404,000.00
Two (2) units are included in this project $808,000.00
4. Track Foundations and Trackage $138,700.00
5. Collector Rail System $ 52,250.00
6. Emergency Drive Car (Trackmobile) $ 35,600.00
7. Emergency Quench Car (Modification)
Estimate includes costs to modify configuration
and increase size of an existing open type quench
car of acceptable condition $ 19,450.00
63
-------
8. Coke Quenching and Distribution System including:
A. Underground track hoppers
B. Vibrating coke feeders
C. Vibrating conveyors
D. Quenching and track hopper emission collection and
control systems including hoods, fume mains, induced
draft fans, scrubbers, mist eliminator and stack.
E. Concrete foundations
F. Quench water recirculation system including equipment
to handle contaminated water from and supply clean
water to the gas cleaning car.
G. Substation control facility including all quench
station instrumentation and controls
H. Quenched coke distribution system
I. Any additional items not specifically listed, but
necessary to this system $3,652,400.00
9. Emergency Dump Fit Including Water Quench System
and Controls $ 112,700.00
10. Emergency Quench Station and Emergency Conventional
Coke Wharf $ 384.700.00
Total $5,907,000.00
64
-------
The distribution of the total cost is estimated as follows:
Engineering and Administrative Expense....$ 977,000.00
Material 2,619,000.00
Labor 2.311.000.00
Total $5,907,000.00
Cost of expanding the initial installation to serve
an additional coke oven battery of similar size.
This includes an additional transfer car, gas
cleaning car, enclosed coke guide, and extension
of the underground facilities to serve two (2)
additional coke hoppers and continuous quenchers...$1,810,000.00
As stated elsewhere in this text, the project estimated cost reflects
a very conservative approach in providing backup protection facilities
and 100% sparing of all critical operating units. As operating
experience is established, it is possible that reductions in overall
costs can be justified as the reliability of the system components
is confirmed.
65
-------
66
-------
SECTION VII
OPERATING COST ESTIMATES
An evaluation of the projected operating and maintenance expense of
the new closed coke quench system as compared to the conventional
quenching system in use at the existing Weirton coke plant is
presented in tabular form.
The tabulation provides a comparison on the basis of operating,
service and maintenance manpower on a facility basis and also on a
tonnage basis. The evaluation involved all facilities from the coke
guide at the oven face through the quenching operation. Distribution
of coke after quenching has been excluded, since no technical differ-
ences are imposed by the system.
The cost of installing and operating the closed coke quench system is
significantly higher in both cases. The prevailing means of handling
and quenching coke provides a simple and economical method. It does
not, however, provide a satisfactory solution to the elimination of
serious pollution problems inherent in this batch process. This new
closed coke quenching system does offer solution to abating pollution in
processing coke from slot type ovens. The cost of this solution is
reflected in higher operating and maintenance charges.
From the ovens through the quench, more equipment and complexity is
involved. Although the equipment utilized represents technology
utilized individually in other applications and as such should perform
reliably in this case, the fact that more apparatus is involved creates
an additional maintenance problem.
67
-------
The use of high quality refractories in the wear areas of the
transfer car and the underground hoppers is expected to support a
reasonable maintenance position in these areas. The use of vibrating
feeders and conveyors in the mainstream of coke processing will most
certainly inflate maintenance considerations.
The skills required to operate and maintain this new system are no
more demanding than those currently employed in coke plant operation.
The complexity of the gas cleaning car-coke transfer car does not
approach that of the modern larry car or pusher machine. It is
anticipated that the current level of skill of the quench car operator
will be sufficient for the coke transfer position. The quench station
operator will be a new position with appropriate training required.
The operation is displayed by graphic means (see Figures 19 and 20) and
the operator's responsibility will be primarily observation and monitor-
ing with actual operation taking place in a semi-automatic mode. The
equipment controls and instrumentation, while adding a substantial
maintenance load, do not add new technology to the current skills
of coke plant maintenance personnel.
Tables 3 and 4 present a comparison of operating labor and maintenance
labor and materials between a new tall oven battery and an existing
coke plant complex of six (6) 13 foot high oven batteries arranged
in two (2) units of three (3) batteries. It is presented on a manhour
basis (Table 3) and on a cost per ton of coke basis (Table 4). While
68
-------
this comparison is meaningful in this particular situation, a comparison
of two (2) modern high production batteries of similar size would present
a significantly different cost prediction. These costs are average, over
the life of the battery. Therefore, it is expected costs will be lower
at the start and somewhat higher as the battery approaches the end of
its useful life.
Table 5 indicates the application of significantly higher connected
horsepower requirements to serve this new system. The most significant
contributors to the increased power requirements are the fans necessary
to the gas cleaning systems. The actual energy requirements reflecting
in operating costs will be specifically determined in the Phase 2
continuing evaluation program.
69
-------
TABLE 3
ESTIMATED OPERATING COST COMPARISON ON A
MAN-HOUR PER WEEK BASIS
Comparison: Mainland
Island
Operating Sequence
Coke Handling from
Oven to Transport
Vehicle
Coke Transport
itteries, 2 Quenching Stations
littery, 1 Quenching Station
Expense Item
Operating Labor M.
Assigned Mechanical
Assigned Electrical
Car & Track Repair
SW Mech. Shops
SW Elect. Shops
Funded Repairs
R & M Materials
Tools & Oper. Supplies
Operating Labor M.
Assigned Mechanical
Assigned Electrical
Car & Track Repair
SW Mech. Shops
SW Elect. Shops
Funded Repairs
R & M Materials
Tools & Oper. Supplies
Basis
H./Week
M II
II II
II II
II II
II II
Ratio
11
ii
H./Week
ii ii
M ii
ii ii
ii ii
ii ii
Ratio
M
n
87 Ovens
New Closed
System
168
83
61
8
35
8
0.75
0.75
0.75
168
134
101
34
57
14
2.00
1.50
2.00
294 Ovens
Conventional
System
672
111
82
11
47
11
to 1.00
to 1.00
to 1.00
336
84
7
22
3
to 1.00
to 1.00
to 1.00
-------
TABLE 3 (cont'd)
87 Ovens
294 Ovens
Operating Sequence
Coke Quenching
Expense Item
Operating Labor
Assigned Mechanical
Assigned Electrical
Car & Track Repair
SW Mech. Shops
SW Elect. Shops
Funded Repairs
R & M Materials
Tools & Oper. Supplies
Basis
M.H./Week
Ratio
New Closed
System
336
312
235
51
132
32
5.00 to
3.50 to
4.00 to
Conventional
System
336
70
17
34
62
3
1.00
1.00
1.00
NOTE: Funded repair costs were estimated over the life of the battery.
These are estimates; these data will be updated with the actual cost figures developed
during Phase 2.
-------
TABLE 4
N>
Comparison: Mainland
Island
Operating Sequence
Coke Handling from
Oven to Transport
Vehicle
ESTIMATED OPERATING COST COMPARISON
ON A MAN-HOUR PER TON OF COKE BASIS
Labor & Material per Ton
Labor & Material per Ton
Coke Transport
Expense Item
Operating Labor
Assigned Mechanical
Assigned Electrical
Car & Track Repair
SW Mech. Shops
SW Elect. Shops
Funded Repairs
R & M Material
Tools & Oper. Supplies
Basis
M.H./Ton
Ratio
n
Operating Labor M.H./Ton
Assigned Mechanical " "
Assigned Electrical
Car & Track Repair
SW Mech. Shops
SW Elect. Shops
Funded Repairs
R & M Material
Tools & Oper. Supplies
n n
Ratio
3,325 Tons
BF Coke/ Day
New Closed
System
0.00721
0.00356
0.00262
0.00034
0.00150
0.00034
1.00
1.00
1.00
4,400 Tons
BF Coke/Day
Conventional
System
0.02181
0.00360
0.00266
0.00035
0.00152
0.00035
to 1.00
to 1.00
to 1.00
0.00721
0.00575
0.00433
0.00146
0.00244
0.00060
,75
.00
2,
2,
2.25
to
to
to
0.01090
0.00272
0.00022
0.00071
0.00009
1.00
1.00
1.00
-------
TABLE 4 (cont'd)
Operating Sequence
Coke Quenching
Expense Item
OJ
Operating Labor
Assigned Mechanical
Assigned Electrical
Car & Track Repair
SW Mech. Shops
SW Elect. Shops
Funded Repairs
R & M Material
Tools & Oper. Supplies
Basis
M.H./Ton
Ratio
3,325 Tons
BF Coke/ Day
New Closed
System
0.01443
0.01340
0.01009
0.00219
0.00567
0.00137
6.50
4.75
5.00
4,400 Tons
BF Coke/ Day
Conventional
System
0.01090
0.00227
0.00055
0.00110
0.00201
0.00009
to 1.00
to 1.00
to 1.00
NOTE: These are estimates; these data will be updated with the actual cost figures developed
during Phase 2.
-------
TABLE 5
ELECTRICAL COMPARISON CONNECTED HORSEPOWER OF MAJOR FACILITIES
Operating Sequence
New
Closed Quench System
Conventional System
A. Coke Handling from Oven
to Transport Vehicle
1. Door Machine, Coke Guide
and Hood
a. Traction Drive 60
b. Hydraulic Pump 25
c. Door and Jamb
Cleaning Devices 1.2
Sub Total 97
Door Machine and Coke
Guide
a. Traction Drive 40
b. Hydraulic Pump 20
c. Door and Jamb
Cleaning Devices 12_
Sub Total
72
B. Coke Transport
1. Transfer Car
a. Sealing Curtain 7%
2. Gas Cleaning Car
a. Venturi Scrubber
Fan 400
b. Water Recirculat-
ing Pumps 20
c. Air Compressor 10
d. Locomotive
Traction Drive 172
1. Quench Car
2. Locomotive
a. Traction
Drive 180
b. Air Compressor
& Misc. 30
Sub Total
609% HP
Sub Total
210 HP
-------
TABLE 5 (cont'd)
-sj
Ul
New
Operating Sequence Closed Quench System
C. Coke Quenching 1. Venturi Scrubber
Induced Draft Fan
400
*2. Quench Steam Induced
Draft Fan 100
*3. Hopper Vibrating
Feeder
*4. Quench Conveyor
5. Quench Water Pump
6. Breeze Pump
7. Control House Air
Conditioning and
Ventilation
Sub Total
Total
5
50
75
50
25
705
1,411% HP
Conventional System
1. Quench Water
Pump 150
2. Breeze Pump 7%
3. Mist Eliminator
Backwash 7%
Sub Total 165
Total 447 HP
*NOTE - Two (2) of the units as indicated would operate concurrently to serve the normal operating
requirements.
-------
76
-------
PAGE NOT
AVAILABLE
DIGITALLY
-------
SECTION VIII
START UP EXPERIENCE
TO JUNE 30. 1973
The Weirton coke plant was made operational on May 30, 1973.
The Enclosed Coke Pushing and Quenching System was complete and
accepted the first coke push on the following day. This section
summarizes the experience demonstrated during the first month
of operation.
The quenching system operated on a sporadic basis during this
start up period. There was an anticipated incidence of debugging
of apparatus and controls under operating conditions, since little
time was permitted for pre-operational debugging due to the start
up schedule requirements.
A problem of serious magnitude became evident almost immediately
after start up. The facilities and design provided to handle and
segregate the fines developed through gas cleaning and coke fines
(breeze) generated through the handling and quenching process have
proven to be inadequate. The preponderance of delay time encounter-
ed at the continuous quencher during this initial operating period
can be attributed to this factor. As this inadequacy became evident,
a two (2) phase program was initiated immediately to support continued
operation of the system. Additional pumping apparatus, immediately
available from in-plant sources, was installed with necessary piping
to bring breeze laden water from the collecting sump in the under-
ground pit to the surface where a temporary decanting sump was
81
-------
constructed. The decanted water is returned to the recirculating
water pump clear well within the pit. The breeze in the temporary
decanting sump is periodically removed by clamshell bucket operated
from a mobile crane.
Engineering was initiated to develop permanent facilities suitable
for long term solution to the breeze segregation and handling problem.
Although these plans are in the formative stage of engineering, it is
probable that the ultimate solution will involve appropriate decant-
ing facilities with mechanical means for removal of breeze and
transport to the coke delivery conveyor system.
The gas cleaning car also encountered difficulty due to particulate
and breeze clogging of the gas cleaning recirculating water system.
It was apparent during this initial operation that the gas cleaning
system was doing a very good job in withdrawing and cleaning all of
the emissions generated during the coke pushing operation. The
volume of particulate collected in the recirculated water was large
and required dumping and replenishment (in part) after each push.
Physical changes to certain piping, the configuration of the water
separator reservoir, and the mechanism for dumping contaminated water
were initiated to overcome these plugging problems.
The basic equipment related to the whole system has operated well
during the first month of operation. While it is certain that minor
82
-------
modification to certain of the facilities will be necessary and
appropriate as operating experience increases, it is equally apparent
at this early stage that the performance of the individual system
components and the system as a whole does provide the emission
abatement capability as predicted.
Definition of any specific changes or additions made to the Enclosed
Coke System will be included in the Phase 2 program, Emission Testing
and System Evaluation to be carried out under EPA Contract 68-02-1347
which was signed June 29, 1973.
83
-------
84
-------
SECTION IX
UNITS OF MEASURE - CONVERSIONS
Environmental Protection Agency policy is to express all measurements
in agency documents in metric units. When implementing this practice
will result in undue cost or lack of clarity, conversion factors are
provided for the non-metric units used in a report. Generally, this
report uses British units of measure. For conversion to the metric
system, use the following conversions:
To convert from
cfm
°F
ft
gal.
gpm
gr/scf
hp
in.
in. we
Ib
tons ( short )/hr
To
nrvsec
°C
m
1
I/sec
mg/Nm3
W
m
N/m2
kg
kg/hr
Multiply by
.0004719
5/9(°F-32)
.3048
3.785
0.0631
2288.136
745.7
.0254
248.84
0.454
907.185
85
-------
86
-------
BIBLIOGRAPHIC DATA
SHEET
Report No.
EPA-650/2-73-028
3. Recipient's Accession Mo.
4. Title and Subtitle
Enclosed Coke Pushing and Quenching System
Design Manual
5. Keport Date
September 1873
6.
7. Author(s)
D.A. Pengidore
8. Performing Organization Kept.
No.
9. Performing Organization Name and Address
National Steel Corporation
Weirton Steel Division
P.O. Box 431
Weirton. West Virginia 26062
10. Pro|ect/Task/Worlc Unit No.
1ARQ13
11. Contract/Grant No.
68-02-0622
12. Sponsoring Organization Name and Address
EPA, Office of Research and Development
NERC-RTP, Control Systems Laboratory
Research Triangle Park, North Carolina 27711
13. Type of Report & Period
Covered
Final
14.
IS. Supplementary Notes
16. Abstracts ^ne manual describes a new concept in abating air pollution normally asso-
ciated with coke pushing and quenching emissions in the iron and steel industry.
The "enclosed coke pushing and quenching system" involves containment of the hot
coke from the face of the slot-type oven during the pushing operation, through the
successive handling and transport, and through a continuous and controlled quench.
The hot coke emissions are confined and cleaned before discharge to the atmosphere
and the quench emissions are controlled to stack discharge of low velocity steam
vapor. The coke plant itself consists of a single battery of 87 "tall" ovens and
complete coal chemical plant and support facilities.
17. Ke> Words and Document Analysis. Ma. IV.srnpturs
Air Pollution
Metallurgical Fuels
Coke
Coking
Iron and Steel Industry
Capitalized Costs
Operating Costs
Scrubbers
17b. Identifiers/Open-Ended Terms
Air Pollution Control
Stationary Sources
Coke Pushing
Coke Quenching
Particulates
Mist Suppressors
17e. COSATI Field/Group l^R 141")
18. Availability Statement
Unlimited
19. Security Class (This
Report)
UNCLASSIFIED
20. Security Class (This
Page
UNCLASSIFIED
21. No. of Pages
95
22. Price
FORM NTIS-3S (REV. 3-721
USCOMM-DC 14952-P72
87
-------
INSTRUCTIONS FOR COMPLETING FORM NTIS-35 (10-70) (Bibliographic Data Sheet based on COSATI
Guidelines to Format Standards for Scientific and Technical Reports Prepared by or for* the Federal Government,
PB-180 600).
1. Report Number. Each individually bound report, shall carry a unique alphanumeric designation selected by the performing
organization or provided by the sponsoring organization. Use uppercase letters and Arabic numerals only. Examples
FASEB-NS-87 and FAA-RD-68-09.
2. Leave blank.
3. Recipient's Accession Number. Reserved for use by each report recipient.
4. Title and Subtitle. Tide should indicate clearly and briefly the subject coverage of the report, and be displayed promi-
nently. Set subtitle, if used, in smaller type or otherwise subordinate it to main title. When a report is prepared in more
than one volume, repeat the primary title, add volume number and include subtitle for the specific volume.
5. Report Date. I .ich report shall carry a date indicating ai least month and year. Indicate the basis on which it was selected
(e.g., date of issue, date of approval, dale of preparation.
6. Performing Organ!totion Code. Leave blank.
7. Author(s). Give name(s) in conventional order (e.g., John K. Doe. or J.Robert Doe). List author's affiliation if it differs
from the performing organization.
8- Performing Organization Report Number. Insert if performing organisation wishes to assign this number.
9. Performing Organization Name and Address, ("uve name, street, c uy, state, and zip code. List no more than two levels of
an organisational hierarchy. Display the name of the organization exactly as it should appear in Government indexes such
as USCRDR-I.
10. Project/Task/Work Unit Number, list the protect, task ami uurk unit numbers under which the report was prepared.
11. Contract/Grant Number. Insi ri contra..t >>r grant number under whit h report was prepared.
12. Sponsoring Agency Name and Address. Ini luJe / ip code.
13. Type of Report and Period Covered, (ruinate interim, final, • 1C., and, if applicable, dales covered.
14. Sponsoring Agency Code. Leave blank.
15. Supplementary Notes, b.ntci information not included c 1st where but useful, such a' Prepared in cooperation with . . .
Translation of ... Presented at eonfunni e of . . 1 o hi published in ... Supcisolc.s . . Supplements . . .
16 Abstract. Im lude- a brief (200 words or less) (actual summary of the most significant information contained in the report.
If the report contains a significant bibliography or literature survey, mention it here.
17. Key Words and Document Analysis, (a). Descriptors. Select from the Thesaurus of I ngmeering and Scientific Terms the
proper authotr/ed terms thut identify the major concept of the research and are sufficiently specific and precise to be used
as index entries for cataloging.
(b). Identifiers and Open-Ended Terms. Use identifiers for proiect names, code names, equipment designators, etc. Use
open-ended terms written in descriptor form for those sublets for which no descriptor exists.
(c). COSATI Field/Group. Field and'Group assignments are to be taken from the 1965 COSATI Subject Category List.
Since the majority of documents are multidise iplmary in nature, the primary Field/Group assignment(s) will be the specific
discipline, area of human endeavor, or type of physical object. The application(s) will be cross-referenced with secondary
Field/Group assignments that will follow the primary postmg(s).
18. Distribution Statement. Denote releasahility to the public or limitation for reasons other than security for example "Re-
lease unlimited". Cite any availability to the public, with address and price.
19 & 20. Security Classification. Do not submit classified reports to the National Technical
21. Number of Pages. Insert the total number of pages, including this one and unnumbered pages, but excluding distribution
list, if any.
22. Price. Insert the price set by the National Technical Information Service or the Government Printing Office, if known.
FORM NTIS-3S (REV. 3-72) USCOMM-OC I4BS2-P7
------- |