EPA-600/2-77-218
October 1977
Environmental Protection Technology Series
DEVELOPMENT OF TECHNOLOGY
FOR CONTROLLING BOP
CHARGING EMISSIONS
Industrial Environmental Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Research Triangle Park, North Carolina 27711
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This report; has been assigned to the ENVIRONMENTAL PROTECTION TECHNOLOGY
series. This series describes research performed to develop and demonstrate instrumen-
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EPA-600/2-77-218
October 1977
DEVELOPMENT OF TECHNOLOGY
FOR CONTROLLING BOP
CHARGING EMISSIONS
by
K.E. Caine, Jr.
National Steel Corporation
Research and Development Department
P.O. Box 431
Weirton, West Virginia 26062
Contract No. 68-02-1370
ROAP No. 21AQR-05
Program Element No. 1AB604
EPA Project Officer: Robert C. McCrillis
Industrial Environmental Research Laboratory
Office of Energy, Minerals, and Industry
Research Triangle Park, NC 27711
Prepared for
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Research and Development
Washington, DC 20460
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ABSTRACT
During charging of liquid pig iron and scrap to the Basic Oxygen Process
(BOP) steelmaking vessel, emissions are generated which are not effectively
collected by the primary emission control system. This study was initiated
by the Environmental Protection Agency for development of technology for
control of the charging emissions.
Literature surveys were conducted on engineering characteristics of
domestic BOP steelmaking plants, the future of the BOP steelmaking process,
theories of emission generation mechanisms, effects of scrap types on
emissions and installations of charging emission systems.
Emission sampling was conducted at a production BOP shop to characterize
the emissions, determine emission velocity and volume and evaluate effects of
scrap type and hot metal pouring time on the emissions.
Tests were made with a 900 kg pilot vessel to evaluate various emission
control systems. Complete instrumentation was provided to measure the
emissions and the effectiveness of the systems investigated. The primary
conclusions of these tests were that slot type hoods are not satisfactory,
inert gas purging of the vessel to suppress emission generation is quite
variable and not practical, the Gaw closure plate system will be effective
if the capture velocity at the vessel mouth is sufficient and if the hood
system has enough volumetric capacity, pouring through the main hood with a
launder is a possibility but poses many problems, a canopy type hood is
satifactory if it is large enough and has sufficient exhaust capacity and
slow pouring reduces the rate of emissions but its effect upon the total
amount of emission is not as pronounced.
An evaluation of advantages and disadvantages from engineering and
operating viewpoints of the four systems which showed a probability of
success in the pilot BOP tests was made.
iii
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CONTENTS
Page
Abstract iii
Contents iv
List of Tables v
List of Figures vi
Acknowledgements ix
Sections
1. Introduction 1
2. Conclusions 3
3. Survey of Domestic Steelmaking Plants 11
4. Future of Steelmaking Processes 22
5. Theories of Emission Generation Mechanisms 26
6. Types of Emissions Possible from Various Scrap Types 27
7. Installations of Emission Control Systems 42
8. Characteristics of BOP Charging Emissions 48
9. Tests of Emission Control Systems with a Pilot Vessel 63
10. Discussion of Applications of Various Charging Systems 120
11. Appendix A - Spark Source Mass Spectrometric Analysis of Sized
Particulate Source Samples 135
12. Appendix B - Statistical Analysis of BOP Charging Emission
Study by Gerald Shaughnessy 149
iv
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TABLES
Number Page
1 Survey of BOP Plants - Location and Size 18
2 Survey of BOP Plants - Primary Emission System Data 19
3 Survey of BOP Plants - Blowing and Gas Cleaning System Data 20
4 Survey of BOP Plants - Charging Equipment and Comments 21
5 Scrap Types and Contaminants 29
6 ISIS Scrap Specifications and Commentary 32
7 Full Size BOP Tests - Charging Materials 54
8 Full Size BOP Tests - Particulate Emission Characteristics 55
9 Full Size BOP Tests - Chemical Compositions of Particulate 56
Emissions
10 Full Size BOP Tests - Chemical Compositions of Particulate 57
Emissions
11 Full Size BOP Tests - Gaseous Emission Characteristics 60
12 Summary of Pilot Vessel Test Heats 76
13 Pilot Vessel Tests - Charging Details 78
14 Pilot Vessel Tests - Transmittance Results 79
15 Pilot Vessel Tests - Dust Loading and Particulate Size of 80
Emissions
16 Pilot Vessel Tests - Gas Composition in the BOP Vessel 81
17 Pilot Vessel Tests - Chemical Compositions of Gaseous Emissions 82
18 Pilot Vessel Tests - Chemical Compositions of Particulate 83
Emissions
v
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FIGURES
Number Page
1 Sketch Illustrating BOP Charging Emissions 2
2 Slot Type Hood Concept 6
3 Inert Gas Purging Concept 7
4 Closure Plate Concept 8
5 Launder Pour Concept 9
6 Canopy Hood Concept 10
7 Raw Steel Production by Process in the United States and Canada 24
8 Raw Steel Production by Process in 29 I.I.S.I. Countries 25
9 Sampling Position at Weirton Steel Division 61
10 Schematic of BOP Charging Emission Sampling System 62
11 Experimental BOP Vessel and Hood 84
12 Photograph of Experimental BOP Vessel 85
13 Photograph of Experimental BOP Vessel 86
14 Slot Hood Details 87
15 Canopy Hood Details 88
16 Launder Pour Details 89
17 Grain Loading Sampling Train 90
18 Particle Size Sampling Train 90
19 Gaseous Emission Sampling Train 91
20 Vessel Gas Sampling Train 91
21 Particulate Sample Collection Train 92
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Number Page
22 Transmittance Measurement Train 92
23 No Emission Control, Heat No. 1 93
24 No Emission Control, Heat No. 2 94
25 No Emission Control, Heat No. 5 95
26 No Emission Control, Heat No. 9 96
27 25 mm Slot Hood, Heat No. 6 97
28 51 mm Slot Hood, Heat No. 3 98
29 102 mm Slot Hood, Heat No. 4 99
30 Argon Purge, Heat No. 7 100
31 Argon Purge, Heat No. 10 101
32 Nitrogen Purge, Heat No, 8 102
33 Nitrogen Purge, Heat No. 11 103
34 Nitrogen Purge, Heat No. 14 104
35 Nitrogen Purge, Heat No. 19 105
36 Closure Plate, Heat No. 12 106
37 Closure Plate, Heat No. 13 107
38 Launder Pour, Heat No. 15 108
39 Launder Pour, Heat No. 16 109
40 Canopy Hood, Heat No. 17 110
41 Canopy Hood, Heat No. 18 111
42 Slow Pour, Heat No. 20 112
43 Slot Hood Gas Velocity Profiles 113
44 Transmittance Results, No Emission Control and Slot Hood Tests 114
45 Transmittance Results, Inert Gas Purge Tests 115
46 Transmittance Results, Closure Plate and Launder Heats 116
vii
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Number Page
47 Transmittance Results, Canopy Hood and Slow Pouring Heats 117
48 Histograms or Emission Particle Sizes 118
49 Histograms or Emission Particle Sizes 119
50 Canopy Hood Concept 132
51 Launder Pour Concept 133
52 Closure Plate Concept 134
viii
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ACKNOWLEDGEMENTS
Participation of the following organizations and personnel during this pro-
ject is gratefully appreciated.
Environmental Protection Agency
Mr. R. C. McCrillis - Project Officer
National Steel Corporation - Research and Development
Mr. J. R. Suitlas - Project Manager
Mr. C. V. DeCaria - Project Engineer
National Steel Corporation - Weirton Steel Division
Mr. D. G. Ralston, Jr. - BOP Superintendent
Mr. A. Sosenko - Assistant BOP Superintendent
Kaiser Engineers
Mr. A. F. Nagy (Deceased)
Mr. J. K. Stone
T.R.W. Transporation and Environmental Operations
Mr. T. E. Eggleston
ix
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SECTION 1
INTRODUCTION
The BOP* steelmaking process is a method of producing liquid steel by
injecting high purity oxygen onto and/or into a mixture of steel scrap,
liquid pig iron produced by blast furnaces (hot metal) and fluxing agents.
The oxygen reacts exothermically with impurities in the metallic charge
thereby simultaneously refining the metal and melting the scrap. Products of
the reactions are high purity liquid steel, liquid slag containing oxides of
the impurities and an offgas mixture consisting primarily of carbon monoxide
and carbon dioxide. All domestic BOP shops have extensive efficient hood
systems located directly above the vessel for collection, cooling and clean-
ing of the offgas and particulate emissions generated during the steelmaking
process. During charging of scrap and hot metal to the vessel prior to the
oxygen blowing operation, the vessel must be tilted out from beneath the
hood system to provide access to the charging mechanisms and emissions
generated during this charging period are not generally captured effectively.
Figure 1 shows this schematically.
Extension of the main hood or installation of an auxiliary hood over the
charging emission area is not practical in many cases because clearances must
be maintained for scrap charging boxes, hot metal ladles and the crane cables
and bails.
This study was conducted to investigate and evaluate methods for con-
trolling the BOP charging emissions. Specific project objectives were:
1. Conduct a survey of existing BOP steel plant configurations with
particular emphasis to hood details.
2. Evaluate the future of the BOP steelmaking process.
3. Investigate theories of emission generation mechanisms.
4. Review published information on effects of charge materials on
charging emissions.
5. Study the effectiveness of various charging emission control systems
that have been tried.
6. Characterize BOP charging emissions by testing at a BOP plant.
7. Construct and operate a pilot BOP plant to investigate various
control methods.
8. Investigate applications of various charging control systems to both
new and existing BOP shops.
*BOP comes from jJasic JDxygen Process or Basic Oxygen JPlant and the term
basic refers to the chemical characteristics of the refractories and slags
employed.
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Offgas Collectio
System
Uncontrolled Emissions
Hot Metal
Transfer Ladle
BOP Vessel
Figure 1. Sketch Illustrating BOP Charging Emissions,
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SECTION 2
CONCLUSIONS
A survey of domestic BOP steelmaking plants illustrated that a wide
range of primary emission control system types and capacities are in opera-
tion. Each shop was designed independently to be the most efficient and
economical system for that shop at the time the shop was designed. Each shop
has independent engineering constraints such as building size, electrical
power availability, steam generation requirements, available space, planned
production rates etc. which dictate the engineering design criteria that must
be satisfied. This means that any considerations of employing the primary
hooding system as part of a charging emission control system must be on a
shop by shop basis.
A historical study of BOP steelmaking developments during the last
twenty-five years showed that the BOP will continue to be the dominant steel-
making process. Additional tonnage will accrue from both expansion of
existing facilities and construction of new facilities.
The type of scrap charged to the BOP has an influence on the type and
amount of emissions generated during hot metal charging. Impurities present
in various types of scrap were identified and discussed. There is a limit on
the amount of high quality scrap available and the usage of lesser quality
scraps containing impurities which result in additional charging emissions
will increase as the world market for steel increases. The charging emissions
problem may therefore possibly become more severe during the next 10 years.
A literature survey of charging emission control systems that have been
installed was conducted. There were fourteen descriptions of installed equip-
ment but data on emission capture effectiveness are meager. Twelve of these
were auxiliary hoods located in the emission area. The main differences
between installations were size and location which were dictated primarily by
individual shop configuration and the type of gas removal and cleaning equip-
ment utilized. Only four of the twelve hoods were reported as being success-
ful but no conclusive supportive data were located. Tests of a closure plate
system which increases the effectiveness of the primary hood system showed
some promise but long term field trials are required to establish reliability
and effectivness. Slot type hoods were not successful.
Emission sampling of a typical large tonnage BOP shop at Weirton Steel
was conducted during the charging operation to characterize the emissions,
determine emission velocity and volume and evaluate effects of scrap type and
hot metal pouring time. Emissions during charging were found to be quite
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variable. Some effects of scrap type were noted but correlations between
emissions and operating variables such as pouring time, hot metal temperature,
percent scrap in the charge, etc. were not observed. Details on dust loading,
particulate and gas compositions, gas velocity and volumetric emission rates
were determined.
A study of charging emission control schemes was conducted with a .90
tonne (1 ton) pilot BOP vessel designed expressly for charging emission con-
trol experiments. Instrumentation was provided to measure the emissions, the
effectiveness of the various systems investigated and the BOP operating
parameters. Twenty heats were made; four had no emission control system in
operation so that baseline conditions could be established, three were with
a slot hood, six employed inert gas purging of the vessel intended to suppress
the emissions at the source, two were for an evaluation of the closure plate
concept, two were launder pours (pouring through the vessel hood), two were
tests of a canopy hood and the last heat was an evaluation of slow hot metal
pouring. Sketches showing these concepts are shown in Figures 2, 3, A, 5 and
6.
It was found from the pilot vessel tests that:
1. At least part of the kish (graphite flakes) observed in particulate
emissions is kish carried over from previous hot metal production and trans-
portation operations. Therefore, a means employed to minimize kish carryover
such as skimming of the hot metal in the transfer ladle, would reduce the
generation of particulate emissions. However, kish has a large particle size
and probably drops out within the BOP shop building; therefore a reduction in
the kish emission may not have a significant influence on emissions exiting
the shop. It is not known if this observation is valid for full size vessels.
2. Slot type hoods are not satisfactory because the effective capture
area, the area adjacent to the hood which will divert gas flow to the hood,
is relatively small.
3, Effects of purging of the vessel with either argon or nitrogen prior
to and during charging were extremely variable; duplicate tests, with
nitrogen purging, for example, showed very good control in one test and
essentially no control in the other. It was concluded that gas purging would
not be practical.
4n The closure plate system was successful at capturing charging
emissions and it was concluded that the system would be effective if the
capture velocity at the vessel mouth is sufficient and if the hood system has
enough volumetric capacity.
5, Pouring through the main hood with a launder was very successful.
6. A canopy type hood would be satisfactory if it is large enough to
encompass the entire plume and if the gas handling system has a large enough
capacity.
7. Slow hot metal pouring reduced the rate of emissions but it was not
determined if the total amount of emissions generated was changed. Further
tests to establish effects of scrap type and the effectiveness on full size
vessels are suggested.
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An evaluation of advantages and disadvantages from engineering and operating
viewpoints of the four systems which showed a probability of success in the
pilot BOP tests was made.
Application of the canopy hood concept to an existing or new BOP
installation will require accurate prediction of fume volumes and velocities
for a variety of hot metal charging operations. Since these conditions are
not completely predictable, the design of canopy hood systems to capture
charging emissions from BOP furnaces would be difficult. Available data
indicate that the emission volume rate required divided by the vessel tonnage
should be in the range of 33 to 81 m3/min/tonne (1100 to 2600 CFM/ton). The
application of a canopy hood will require consideration of the type of
existing air pollution control system and existing fan capacity, and dimen-
sional restrictions and operating clearances unique to individual shops.
Major advantages of the canopy hood concept are that it would involve minimum
constraints and changes to operating practices, and that auxiliary mechanical
or electrical devices are not required in the immediate vicinity of the
furnace.
The launder pour concept utilizes a launder to transfer hot metal from
the charging ladle to the furnace. The hot metal is conveyed by gravity
along a refractory-lined launder which is inserted through a port in the
lower section of the main exhaust hood. During hot metal additions, the
furnace would be in an almost vertical or upright position and, therefore,
the charging emissions would be captured by the main exhaust hood. Applica-
tion of the launder pour concept will require a verification that the existing
main gas cleaning system will handle charging emissions, design changes to the
hood and its cooling system, the determination if sufficient headroom is
available for the change in ladle pouring position and the design of the
launder arrangement. Procedural changes will be required which may reduce
productivity.
The closure plate concept utilizes a retractable closure plate to
restrict the main hood intake opening while the furnace is located at the
position for conventional hot metal charging. The partial restriction in
hood intake cross-sectional area results in an increased velocity of air flow
through the open portion, thus enabling the hood to more effectively capture
charging emissions for cleanup by the shop's main gas cleaning system.
Application of the closure plate concept will require verification that the
gas cleaning system can handle charging emissions and an examination of the
physical clearances available in the shop. Operation with a closure plate
may result in delays in the production cycle and, since this mechanism is
operated in the harsh furnace environment, maintenance problems may be
anticipated.
Tests performed with the BOP pilot plant indicated that the use of
slower-than-normal rates of hot metal pouring during charging resulted in a
lower rate of emissions. The slow hot metal pouring rate would have a serious
impact on the production output of a BOP plant since production efficiency is
a function of the tap-to-tap cycle time of the furnace. For a typical
tap-to-tap time of 45 minutes, an increase in hot metal charging time of 1
minute would reduce productivity by 2.2%.
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Slot Hood
Figure 2. Slot Type Hood Concept.
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Inert Gas
Figure 3. Inert Gas Purging Concept.
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Closure
Plate
Figure 4. Closure Plate Concept,
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Figure 5. Launder Pour Concept.
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Canopy Hood
Figure 6. Canopy Hood Concept,
10
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SECTION 3
SURVEY OF DOMESTIC STEELMAKING PLANTS
BRIEF DESCRIPTION OF BASIC OXYGEN STEELMAKING PROCESSES
BOP steel is made in a cylindrical vessel similar to a bessemer con-
verter. The BOP vessel, however, has a solid bottom and no tuyeres. Oxygen
is introduced by a vertical water-cooled lance inserted through the vessel
mouth. The converter can be tilted on trunnions which have an axis
perpendicular to the lance and situated at the largest section of the vessel.
The vessel is tilted for charging and tapping, but is stationary and upright
while blowing and refining. The lining is chemically basic and similar to
that used in basic open hearths, electric furnaces, and Thomas converters.
Blowing normally requires about 20 minutes and the full cycle including
charging, blowing, testing, tapping, and alloying, is 30 to 60 minutes.
LD-AC Process is a European modification of the BOP Process in which
powdered lime is blown with the oxygen to assist in forming an early fluid
slag for removal of high phosphorus contained in some European iron ores.
This practice was developed cooperatively by ARBED, the steel company of
Luxembourg and Centre National de Recherches Metallurgiques (CRM), a
governmental research organization at Liege, Belgium.
The OLP Process (Oxygen/Lime Powder) is very similar to LD-AC in
principle, purpose, and application and was developed independently for the
producers of Thomas Steel in France by IRSID, the French National Research
Institute. Both LD-AC and OLP have been widely practiced in Europe where
high phosphorus ores and Thomas iron must often be utilized, but never used
in the United States.
The Kaldo Process employs a rotating vessel of similar shape which is
blown with its axis inclined about 17° above the horizontal. The lance is
introduced through the vessel nose at an angle and blows oxygen lightly onto
the slag.
During blowing the vessel is rotated to mix slag and metal, to dis-
tribute heat from the reactions, and to attempt to prolong the refractory
life. Variations of the original process employed two lances, one of which
was submerged. Because of the slow blowing, the process requires up to two
hours per heat, but melts a higher proportion of scrap than a conventionally
operated basic oxygen furnace. One plant was built in the United States,
two in Sweden, and several more in other countries. The two-furnace plant
in the United States has been virtually supplanted by a BOP furnace.
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Thti Rotor Process is similar in principle to the Kaldo, but the vessel
has larger dimensions and is shaped like a cylindrical hot metal mixer or a
large diameter rotary kiln. Two lances are employed; one submerged, and one
above t'.ie bath to burn the CO to C02. Rotation of the larger vessel is
about two r.p.m. Although used at one time in Germany at both Oberhausen and
Peine, Lt is now apparently used only in South Africa.
OBM or Q-BOP, the latest basic oxygen process, originated in Europe as
OBM and is being promoted in the United States by U.S. Steel Corporation and
Pennsylvania Engineering Corporation (Pecor). So far, two plants are in
operation within U.S. Steel, and Pecor is converting an open hearth shop to
Q-BOP for Republic Steel, in Chicago.
The OBM, or Q-BOP, process is carried out in a modified basic-lined
converter which is fitted with bottom tuyeres through which both oxygen and
a hydrocarbon gas are injected. Concentric tuyeres are built into the bottom
so that the oxygen enters the bath shrouded by a shield of hydrocarbon gas
through the larger of two concentric pipes. On entry into the vessel, the
hydrocarbon is cracked endothermically, thus absorbing the heat that would
otherwise be liberated where the oxygen first contacts the molten metal. This
absorption of heat protects the tuyeres from rapid erosion that took place in
previous attempts to bottom blow with oxygen. The fact that the oxygen is
blown through the bottom rather than from above changes the character of the
slags. Powdered lime is blown in through the bottom tuyeres with the oxygen
to assist in obtaining a slag that is effective in removing phosphorus and
sulfur from the bath. This slag apparently develops a much lower iron oxide
content: than the slags made in the conventional BOP process.
SURVEY RESULTS
The results of this survey of present BOP plants are summarized in
Tables 1 to 4. Table 1 shows the steel companies, plant locations, dates of
start-up, and number and sizes of the furnaces.
Type o:: Hood
"Type of Hood," Table 2, lists the different kinds of hoods as designated
in the literature. There are, however, only two general types of hoods in
common usage: plate hoods and membrane wall hoods. Plate hoods are usually
constructed with panels so that the water flow can cool the entire surface in
an effective manner. This was the type of hood built on most early furnaces.
Beginning in 1963, membrane wall hoods were installed in several plants,
especially where high pressure steam or water was used for cooling, and
pressure vessel certification was required. There are several different
designs of membrane wall hoods referred to by several different names in the
literature; these names have been used without change in the Tables.
There is a third type of hood, which has had only a limited application.
It is the water-cooled elbow hood installed on the top-charged vessels of
McLouth Steel in Detroit.
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Hood Cooling
The most prevalent method of hood cooling utilized is unpressurized cold
water cooling (designated "Water" in the Tables), of which there are 24
installations. There is also one plant using high-pressure water for cooling
(designated as "Water, High Pressure"). In the East Chicago plant of
Youngstown Sheet & Tube Company, the water is cooled by means of a water-to-
air heat exchanger and is reused. There are two different schemes for steam
cooling mentioned in the literature, steam generation and steam condensed
systems. In the steam generation system water is evaporated to steam and
used in the plant. This scheme is used by 7 plants. In the steam condensed
system water is evaporated, condensed, and recirculated in the hood system.
Two plants use this system.
There are eight plants on which data are not available.
An article by E. Durham, of Babcock and Wilcox Company, appeared in
IRON AND STEEL ENGINEER for April, 1964; and in OXYGEN STEELMAKING. published
in 1966 by the Association of Iron and Steel Engineers (AISE), which contains
extensive information on membrane hoods and waste heat boilers.
Gas Cooling
"Gas Cooling" refers to the means by which the gases are cooled after
leaving the hood and before they enter the precipitator or the scrubber.
When a precipitator is used for gas cleaning, water is sprayed into the gas
stream to cool the gases to below 288°C (550°F), and also supply moisture
needed to condition the gases for precipitation. When venturi scrubbers are
used for gas cleaning, the water is often used in low pressure-drop
"quenchers."
The Tables show 25 plants using sprays, 7 using water quench and 4 are
simply designated as using "water." All plants using "water quench" or
"water" utilize scrubbers or venturi scrubbers. There are no data on seven
plants, but cooling is undoubtedly by water in some form.
Dust Removal Systems
The column labeled "Dust Removal Systems," classifies the systems as
either 'precipitator' (dry), 'scrubber1 (wet), or 'venturi scrubber' (wet).
It is doubtful whether there is a real difference between the 'scrubber' and
'venturi scrubber', but the nomenclature has been retained from the sources
utilized.
The survey shows 19 plants using precipitators; and 18 using scrubbers,
which are designated as either 'scrubber' or 'venturi scrubber.' There is
one 'disintegrator' (wet) utilized at McLouth; this is of the rotating-type
originally sold by Thyssen, of Germany. No information is available on 5
plants. A discussion of the considerations in choosing a wet or dry system
13
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follows:
Comparison of Dry and Wet Cleaning
In the overall picture, there is little clear-cut superiority for either
a 'wet' scrubber or the 'dry1 electrostatic precipitator. When properly
designed, installed, maintained, and operated; either system will meet most
standards. The choice depends on the conditions at the site of the installa-
tion. Among the characteristics which have dictated the choice in the
various locations, the following are the most important:
Scrubber
(1) The wet scrubber requires more fan capacity to develop
the high pressure-drop that is necessary for high
efficiency gas cleaning. As a result, the fan power
requirements will be higher than those for a precipitator.
(2) Water is required in large quantities for a scrubber.
The effluent water as well as the gas must meet the
local codes.
(3) Maintenance of a scrubber is less than that of a
precipitator.
(4) Only wet systems are considered safe by most suppliers
for use on closed hood gas recovery systems, such as the
Japanese "OG" system.
Precipitator
(1) The precipitator requires less fan horsepower than
that required for a scrubber because a high pressure
drop is not required.
(2) The so-called 'dry' precipitator requires about 15%
moisture in the gas to attain reasonable gas cleaning
efficiency. This moisture must be supplied by injecting
steam during the early parts of the blow when gas
temperatures are insufficient to evaporate sufficient
amounts of cooling water to supply the moisture.
(3) Maintenance required to keep the precipitator, gas
collection, rapping, and discharge systems operating
efficiently is more sophisticated than that required
for wet scrubbers.
Blowing Rate and Gas Cleaning System
Table 3 shows the design blowing rate. The columns headed "Gas Cleaning
System" list the fan gas volumes and, where available, fan horsepower.
Types of Charging Equipment
The column headed "Types of Charging Equipment," Table 4, lists the types
of scrap charging equipment.
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Four different types of charging equipment were found:
1. The first and most widely used type is the tilting box
charging car carrying either one, two, or four boxes.
There are 23 plants using this general type of charger.
2. The second is crane handled charging boxes; 10 plants
use this system.
3. The third is the right-angle funnel of Calderon design.
There were 5 of these in service.
4. The fourth type is the electric furnace basket, in use
only at McLouth Steel Corporation.
There are 5 plants for which no information is currently available.
The choice between the charging car and crane is one that is made
largely on the basis of the relative cost and usefulness of the additional
crane, as opposed to the single-purpose charging car. The electric furnace
charging basket used at McLouth Steel Corporation has not been used elsewhere
in the United States because no other shops are designed for vertical
charging.
Comments
The last column of the Tables labeled "Comments" indicates, among other
things, the plants now using or planning one of the limited-combustion closed
hood oxygen converter gas recovery processes, the various types of which are
described below. The other comments give information on spare scrubbers and
fan capacity, when it has been available.
Limited-Combustion Gas Collection Systems
The basic oxygen process off gases consist largely of carbon monoxide
together with a small proportion of carbon dioxide. Early BOP furnaces all
had full-combustion or open hood systems. Large quantities of air were drawn
into the hood above the vessel mouth in order to burn all of the hot CO gas
to C02 before the gas was cleaned. This technique required that large
quantities of heat generated by the combustion of CO be absorbed and made it
necessary to clean not only the furnace gases, but also the oxygen and
nitrogen from the combustion air drawn into the hood. By limiting the excess
air, and cleaning only the mixture of CO and C02, the gas volume to be
cleaned can be reduced.
The Yawata Steel Company in Japan was the first to devise a workable
suppressed combustion system which is known as the "OG" System. This system
relies on a movable skirt positioned during a heat to limit the amount of air
drawn into the hood. The system utilizes nitrogen as a purging agent to
prevent explosions.
Shortly after the first commercial application of the "OG" System, IRSID,
of France, developed a similar limited-combustion system. This system relies
more upon equalization of the pressure inside and outside the hood and less
on hood-to-vessel sealing to limit the influx of air. As time goes on, and
15
-------
more and more of the "OG" and IRSID Systems are installed, the two systems
become more and more similar; "OG" now uses less nitrogen-purging than it did
originally, while IRSID does not rely as heavily on pressure-control. Both
manufacturers have specified a wet scrubber for cleaning the combustible
gases, ,ind have also specified that each furnace have a separate gas cleaning
system :Ln order to avoid the danger of 'dead spots' in the system and leakage
around large valves used to connect two vessels to one gas cleaning system.
Ar-.icles on the "OG" and IRSID Systems appear in IRON AND STEEL ENGINEER
for December, 1962 and March, 1966, respectively. Both have been reprinted
in OXYGEN STEELMAKING, 1966, by AISE. These articles give good background
on these two most widely-used limited combustion systems.
Baiimco has recently developed a system similar to the "OG" System. The
closed system for the third vessel at Bethlehem Steel-Burns Harbor is to be
supplied by Baumco. Baumco supplied the gas cleaning systems for the U.S.
Steel-Fairfield Q-BOP, and presumably will supply the system for the Republic
Steel-Chicago Q-BOP shop.
The: Krupp system employs an auxiliary ring-shaped hood which is
installed concentrically around the main hood where it joins with the top of
the vessel to prevent air from entering or gas from escaping from the main
gas system at the vessel mouth. Through this outside hood a small amount of
gas is withdrawn; burned with air; and cleaned in a separate system. The
amount of gas withdrawn and burned is regulated by the pressure in the main
gas system. The bulk of the unburned gases is collected by the main or inner
hood anc. cleaned without burning.
DISCUSSION
The most pertinent observation relevant to the BOP charging emissions is
the extremely wide range of systems and system capacities* Each shop was
designed independently to be the most efficient and economical system for that
particular shop at the time the shop was designed. Each shop has independent
engineering constraints such as building size, electrical power availability,
steam generation requirements, available space, planned production rates etc.
which dictate the engineering design criteria that must be satisfied.
This means that any considerations of employing the primary hooding
system as part of charging emission control system must be on a shop by shop
basis.
REFERENCES
This literature search covered the following technical publications:
Iron and Steel Engineer
Journal of Metals (AIME)
Iron and Steelmaker (I&SM) (AIME) (since December, 1974)
Proceedings of the Open Hearth and Basic Oxygen Committee
"33" Magazine (since 1964)
16
-------
Ironmaking & Steelmaking (London) (since 1974)
Blast Furnace and Steel Plant (prior to 1971)
Yearbook of American Iron and Steel Institute
Selected Annual Reports of the steel companies
Miscellaneous foreign periodicals
17
-------
TABLE 1. SURVEY OF BOP PLANTS - LOCATION AND SIZE
Alan Wood Steel
Allegheny Ludlura Steel
Armco Steel
ii
Bethlehem Steel
CF & I Steel
Crucible Inc.
Ford Motor Company
Inland Steel
M
Interlake, Inc.
Jones & Laughlin Steel
Kaiser Steel
McLouth Steel
National Steel
Republic Steel
Sharon Steel
United States Steel
Wheeling-Pittsburgh
it
Wisconsin Steel
Youngs town Sheet & Tube
*Q-BOP
Furnaces
Plant Location
Conshohocken, Pa.
Natrona, Pa.
Ashland, Ky.
Mlddletown, Ohio
Lackawanna, N.Y.
Sparrows Point, Md.
Bethlehem, Pa.
Burns Harbor, Ind.
it
Johnstown, Pa.
Pueblo, Colo.
Midland, Pa.
Dearborn, Mich.
East Chicago, Ind.
it
Chicago, 111.
Aliquippa, Pa.
ii
Cleveland, Ohio
Fontana, Calif.
Trenton, Mich.
Ecorse, Mich.
ii
Weirton, W.Va.
Granite City, 111.
Warren, Ohio
Gads den, Ala.
Cleveland, Ohio
Buffalo, N.Y.
South Chicago, 111.
Farrell, Pa.
Duquesne, Pa.
Gary, Ind.
Gary, Ind.*
South Chicago, 111.
Lorain, Ohio
Braddock, Pa.
Fairfield, Ala.*
Monessen, Pa.
Steubenville, Ohio
South Chicago, 111.
East Chicago, Ind.
Campbell, Ohio
Plant
Code
A
B
C
D
E
F
G
H
I
J
K
L
M
N
0
P
Q
R
S
T
U
V
W
X
Y
Z
AA
BB
CC
DD
EE
FF
GG
HH
II
JJ
KK
LL
MM
NN
00
PP
QQ
Date of
Start-Up
1968
1966
1963
1969
1964/66
1966
1968
1969
1976
1978
1961
1968
1964
1966
1974
1959
.1957
1968
1961
1958
1958/69
1962
1970
1967
1967
1965
1965
1966
1970
1976
1974
1963
1965
1973
1969
1971
1972
1974
1964
1965
1964
1970
1976
No. &
N.T.
2 x 150
2 x 80
2 x 180
2 x 210
3 x 300
2 x 215
2 x 270
2 x 300
1 x 300
2 x 200
2 x 120
2 x 105
2 x 250
2 x 255
2 x 210
2 x 75
2 x 80
3 x 190
2 x 225
3 x 120
5 x 110
2 x 300
2 x 235
2 x 350
2 x 235
2 x 190
2 x 180
2 x 245
2 x 130
2 x 200
1 x 150
2 x 215
3 x 215
3 x 200
3 x 200
2 x 225
2 x 230
3 x 200
2 x 200
2 x 285
2 x 120
2 x 280
2 x 200
Size
M.T.
135
75
165
190
270
195
240
270
270
180
110
95
225
230
190
70
75
170
205
110
100
270
215
320
215
170
165
220
120
180
135
195
195
180
180
205
210
180
180
260
110
255
180
18
-------
TABLE 2. SURVEY OF BOP PLANTS - PRIMARY EMISSION SYSTEM DATA
Plant
Code
A
B
C
D
E
F
G
H|
l'
J
K
L
M
N
0
P
Q
R
S
T
U
V
w
X
Y
Z
AA
BB
CC
DD
EE
FF
GG
HH
II
JJ
KK
LL
MM
NN
00
PP
QQ
(*)
Type of Hood
Membrane Tubes
Paneled Plates
Membrane Tubes
Membrane
Plate and Tubes
Membrane Tubes
Finned Tubes
Tubes
-
-
Paneled Plates
Paneled Plates
Membrane Tubes
Paneled Plates
-
Paneled Plates
Paneled Plates
Paneled Plates
Paneled Plates
Paneled Plates
Water-Cooled Elbow
Paneled Plates
Membrane Tubes
Membrane Tubes
Paneled Plates
Paneled Plates
Paneled Plates
Paneled Plates
-
-
-
Membrane Tubes
Plate
Plate
Paneled Plates
Membrane
Paneled Plates
-
Membrane Tubes
Paneled Plates
Paneled Plates
Membrane Tubes
—
Assumed
Hood Cooling
Steam Generation
Water
Steam- Condensed
Water
Steam-Condensed
Steam Generation
Steam Generation
Steam Generation
-
-
Water
Water
Steam Generation
Water
-
Water
Water
Water
Water
Water
Water
Steam Generation
Water
Steam Generation
Water
Water
Water
Water
-
-
-
Water
Water
Water
Water
Water
Water
-
Water, High Pressure
Water
Water
High Pressure/Water
Heat Exchangers
—
Gas Cooling Dust Removal Syste
Water Sprays
Water
Water Sprays
Water
Water Sprays
Water Sprays
Water Sprays
Water Quench
-
-
Water Sprays
Water Quench
Water Sprays
Water Quench
Water Quench
Water Sprays
Water Sprays
Water Sprays
Water Sprays
Water Sprays
Water Sprays
Water Sprays
Water Sprays
Water Sprays
Water Sprays
Water Sprays
Water Sprays
Water Sprays
-
-
-
Water Quench
Water Quench
Water Sprays
Water Quench
Water
Water Sprays
-
Water Sprays
Water
Water Sprays
Water Sprays
—
Precipitator
Scrubber
Precipitator
Scrubber
Scrubber
Venturi Scrubber
Precipitator
Scrubber
Scrubber (*)
-
Precipitator
Scrubber
Precipitator
Venturi Scrubber
Scrubber
Precipitator
Precipitator
Precipitator
Precipitator
Precipitator
Disintegrator
Precipitator
Precipitator
Scrubber
Precipitator
Precipitator
Precipitator
Precipitator
-
Scrubber (*)
-
Venturi Scrubber
Venturi Scrubber
Venturi Scrubber
Venturi Scrubber
Venturi Scrubber
Venturi Scrubber
-
Precipitator
Venturi Scrubber
Precipitator
Precipitator
—
19
-------
TABLE 3. SURVEY OF BOP PLANTS - BLOWING AND GAS CLEANING SYSTEM DATA
Design Gas Cleaning System
Plan:
Code
A
B
C
D
E
F
G
H
I
J
K
L
M
N
0
P
Q
R
S
T
U
V
W
X
Y
Z
AA
BB - -
CC - - - - -
DD - - - - - -
EE - - - - - -
FF - - - - - -
GG - -
HH - - - - - -
II 566 20,000 5,700 202,000
JJ 566 20,000 1,300 47,500 1680 2250
KK - - -
LL - - - - - -
MM 420 15,000 17,000 @ 288°C 600,000 @ 550°F -
NN 650 23,000 - - - -
00 340 12,000 16,000 570,000 1680 2250
PP 740 26,000 17,800 630,000 2800 3750
QQ - -
Blowing
m^/min.
420
180
420
640
710
620
620
990
180
310
620
620
110
170
370
566
370
_
-
710
620
420
420
Rate
CFM
15,000
6,500
15,000
22,500
25,000
22,000
22,000
35,000
6,500
11,000
22,000
22,000
4,000
6,000
13,000
20,000
13,000
_
-
25,000
22,000
15,000
15,000
m3/min
17,000
8,900 @
20,000
1,600
28,000
20,000
42,000
16,000 @
8,500
9,900
42,000
—
5,700 @
6,460 @
-
37,000
16,000
35,700
18,000
12,000
28,000
20,000
20,000 @
Capacity
CFM
600,000
288°C 314,000 @
700,000
55,000
1,000,000
700,000
1,500,000
82°C 570,000 @
300,000
350,000
1,500,000
—
93°F 200,000 @
293°F 228,000 @
-
1,300,000
550,000
1,260,000
650,000
420,000 @
1,000,000
720,000
288°C 700,000 @
Motor
KW
1040
550°F 2610
-
1490
670
5590
-
180 °F 3360
520
3730
-
—
200°F -
560°F 370
-
3700
—
2240
1190
140°F 1840
-
-
550°F 1340
Power
H.P.
1400
3500
-
2000
900
7500
-
4500
700
5000
-
—
_
500
-
5000
-
3000
1600
2470
-
-
1800
20
-------
TABLE 4. SURVEY OF BOP PLANTS - CHARGING EQUIPMENT AND COMMENTS
Plant
Code
A
B
C
D
E
F
G
H
I
J
K
L
M
N
0
P
Q
R
S
T
U
V
W
X
Y
Z
AA
BB
CC
DD
EE
FF
GG
HH
II
JJ
KK
LL
MM
NN
00
PP
QQ
Type of
Charging Equipment
2-Box Charger
4-Box Charger
Right-Angle Funnel
2-Box Charger
Charging Car
2-Box Charger
Crane Charged
Charging Car
Charging Car
Right-Angle Funnel
2-Box Charger
Charging Car
Right-Angle Funnel
Right-Angle Funnel
Crane Charged
4-Box Charger
2-Box Charger
Crane Charged
Crane Charged
Electric Furnace Basket
2-Box Charger
2-Box Charger
Crane Charged
2-Box Charger
2-Box Charger
2-1 Box Cars
2-Box Charger
2-Box
2-Box
Crane
Crane
Crane
Crane
Crane
2-Box
2-Box
1-Box
1-Box
Charger
Charger
Charged
Charged
Charged
Charged
Charged
Charger
Charger
Charger
Charger
Comments
300,000 SCFM fan in reserve
Closed Hood "OG" System
Third Furnace has full Membrane Hood
Closed Hood - "Baumco"
Details not available as of July, 1975
One Spare Scrubber
Closed Hood "OG" System
Plant now out of operation
Converted from right-angle funnel
One fan in reserve
One fan in reserve
IRSID Closed Hood being installed
Data Not Available
To be built in open hearth building
Replaces a 2-furnace Kaldo Shop
Late-stage change from BOP to Q-BOP
Closed Hood "OG" System
Open Hearth Shop converted to Q-BOP
One fan in reserve
21
-------
SECTION 4
FUTURE OF STEELMAKING PROCESSES
A isurvey of the development of steelmaking processes was conducted by
reviewing available pertinent literature. Obtaining accurate data on a
worldwide basis is difficult because many countries do not publish accurate
information.
Proportions of total raw steel production for the various steelmaking
processes in the United States and Canada during the last 25 years are shown
in Figure 7.* During the early 1950's about 90 percent of the steel was made
in open hearth furnaces, seven percent was from electric furnaces and three
percent was produced in Bessemer converters. The BOP process was developed
commercially in the late 1950's and a gradual replacement of open hearth
and Bessemer furnaces occurred. The primary reasons for adoption of the BOP
process are lower capital and operating costs. Other factors are hot metal
and scrap availability, equipment obsolescence and costs involved to install
and operate emission control equipment.
From 1962 to 1972, inclusive, the percentage of BOP furnaces increased
from 5.6 percent to 56.0 percent at a rate of about 5.0 percent increase per
year. The open hearth furnace declined during the same period from 84.A to
26.2 percent at a rate of 5.8 percent per year. During the period 1972 to
1976, the rate of change in proportions changed; the BOP percentage increased
from 56.0 to 62.4 percent at a rate of 1.3 percent increase per year and the
open hearth decreased from 26.2 to 18.3 percent, a rate of 1.6 percent de-
crease per year.
The decrease in the rates of change during the past five years is related
to considerations other than a simple consideration of BOP steelmaking versus
other processes. The remaining open hearth shops are relatively modern and
efficie.nt and, therefore, the economic incentive for replacement is not as
strong. In addition, several companies have delayed construction of new BOP
shops because of unfavorable business conditions.
The number of electric furnace shops has increased steadily during the
past 20 years. The percentage of steel made in electric furnaces has
increased from 7.5 percent in 1956 to 19.2 percent in 1976. This, in general,
is a result of the development of both the specialty steel market and the
emergence of mini-mills which produce a limited range of products to localized
markets;.'
*Data from American Iron and Steel Institute (AISI) Annual Statistical
Reports1..
22
-------
Figure 8 shows International Iron and Steel Institute (IISI) data for the
29 IISI countries. The IISI represents the bulk of world production exclu-
sive of the USSR and Communist countries. (The scales of Figures 1 and 2 are
the same for ease of comparison.) The changes in the proportions of the
various processes are essentially the same. The only significant difference
is that the percentage of world production by the BOP process is greater by
about four percent for the IISI countries than for the United States and
Canada. (Note that the IISI data includes United States and Canada and the
actual difference between the United States and Canada and the other IISI
countries obtained by deducting the United States and Canada from the IISI
totals is about five percent.) The rates of growth for the BOP and electric
furnace processes and the decline of the open hearth are about the same as
for the United States and Canada.
It appears from the trend lines that the BOP process will continue to be
the dominant steelmaking process and that further increases in BOP tonnage
can be expected in the future. The increases will occur because of open
hearth process replacement and expansion of steelmaking capacity.
23
-------
100,
DATA FROM
A.I.S.I.
1957
1962
1967
1972
1977
Year
Figure 7. Raw Steel Production by Process in the United States and Canada.
24
-------
100
c
o
•H
iJ
O
•o
o
0)
-------
SECTION 5
THEORIES OF EMISSION GENERATION MECHANISMS
DISCUSS::ON
A literature survey for information on mechanisms of emission generation
that occur during BOP charging was unproductive. There are several papers on
fume generation during blowing of iron with oxygen which indicate that the
fume emitted during blowing results from bursting of carbon monoxide bubbles
and subsequent oxidation of ejected bubbles (1,2,3). Experiments of
injecting fuel oil, gas and steam with the oxygen have had limited success on
suppression of fumes.
It is readily apparent from observations of charging emissions that part
of the smissions are generated by burning of combustibles in the scrap. It
has been observed frequently that the amount of the visible flame generated
is a function of the type of scrap charged; high quality, more expensive
scraps exhibit less emissions than dirty junk-laden scraps. The following
section describes types of scraps and possible emissions therefrom.
BIBLIOGRAPHY
1. Morris, J. P., Riott, J. P. and Illig, E. G., "A New Look at the Cause of
Fuming," Journal of Metals, July, 1966, pp. 803-810.
2. Rengstorff, G. W. P., "Formation and Suppression of Emissions from
Steelmaking Processes," Proceedings of Open Hearth Steel Conference,
1961, Vol. 44, pp. 120-146.
3. Ellis, A. F. and Glover, J., "Mechanism of Fume Formation in Oxygen
Steelmaking," Journal of The Iron and Steel Institute, 1971, pp. 593-599.
26
-------
SECTION 6
TYPES OF EMISSIONS POSSIBLE FROM VARIOUS SCRAP TYPES
There are a number of identifiable sources of emissions in scrap charged
to the BOP. Table 5 is a summary of scrap types and scrap contaminants and
Table 6 is a detailed description of ISIS (Institute of Scrap Iron and Steel)
specifications with a capsule commentary. In summary these tables show that
oil and grease occur principally on turnings and borings, machinery, unpre-
pared automotive scrap, uncleaned cans, and containers. They can occur in
any scrap. Bulky scrap will absorb and hold more of this contaminant than
heavy, densely-packed scrap.
The principal origin of tar and related materials is in undercoating
materials in unprepared autobody scrap and tar-coated roofing materials. Only
burning or pulverizing and sorting will reduce the amount of contaminants.
Paint, lacquer and inorganic coatings occur in unincinerated automobile
scrap, scrap cans, and, in smaller quantities, on salvaged structural steel.
The baled lighter-gauge material will be the worst offender because of the
higher ratio of surface area to weight.
In-plant mill scrap from hot mills contains some mill scale. The pro-
portion of scale and therefore fuming increases as the scrap pieces become
thinner and the scrap density decreases. Salvaged scrap from used equipment
also has some rust. The amount of rust will vary with the age of the
structure from which the scrap was derived and the degree of protection
afforded it with paint, galvanize, or other coatings.
Zinc in scrap reacts readily with oxygen during hot metal charging to
produce dense ZnO fumes. The primary source of zinc in scrap is galvanized
steel from end-use products such as roofing, ventilation ducts and light
structural steel sections. Segregation of galvanized scrap is usually
employed during preparation of higher quality scraps but lesser scrap
qualities may contain galvanized steel from miscellaneous sources such as
garbage cans, automotive parts, pipe and conduit.
Lead reacts to form PbO during charging and the primary source of lead
in scrap is terne plate, lead coated steel. Production of terne plate in
recent years has decreased and the amount of scrapped terne plate is quite
small. Recently the price of recoverable lead has been relatively high and
scrap dealers carefully segregate lead scrap for sale to lead producers.
Consequently, easily separated lead scrap such as from automobile batteries
is not often found in steel plant scrap.
27
-------
The production of tin plate, tin-free steel (chrome plate), and black-
plate ii5 about 7% of all steel shipments. It must therefore be expected that
some finds its way into bundled or shredded scrap. Most scrap tin plate
however is detinned to recover the tin and is charged to blast furnaces rather
than to BOP furnaces.
The major source of miscellaneous combustibles is unprepared and incom-
pletely prepared auto hulks. Upholstery material, wood, plastic, rubber, tar,
oil, paint, and volatile non-ferrous materials can be left in the auto hulks,
and thereby can be incorporated in the scrap shipped to the steelmaker.
The amount of combustibles can range up to 10% of the automobile's weight
if hone of it is removed. Various studies have shown that removal of most
of this material from the auto hulk is easy and cheap, for example, upholstery,
which is? easily accessible. To remove electrical insulation, rubber bushings,
small plastic parts, and undercoating is time-consuming and expensive; and
not often done. Therefore, incineration or shredding, followed by sorting,
levitation, and magnetic separation is the only effective means of removing
these contaminants. At one time, burning of automobile hulks was more
prevalent, but since open burning has been banned in many areas, an increased
amount of this type of charging fume may be expected. Confined burning and/or
adequate sorting after shredding is, of course, desirable.
The volatile and combustile surface contaminants adhering to scrap con-
tribute greatly to the emission of charging fume when the scrap is charged
into a 30F. Consequently, the amount of surface on the scrap is very impor-
tant as a measure of the potential for producing charging fume. Although
the surface per ton of scrap varies inversely with the bulk density of scrap,
the ISIS Specifications contain specific limits on density in only 9 of the
28 specifications in common use. All 9 are specifications for bundles or
shredded scrap on which the risk of excessively bulky scrap is the greatest.
The expected density of the other grades generally decreases as you progress
from No. 1 Heavy Melting (ISIS No. 200) at about 4000 kg/m3 (250 Ib/cu. ft.),
to the ones covering Turnings, such as Nos. 219 to 227, which can be very
light a:id bulky.
28
-------
TABLE 5. SCRAP TYPES AND CONTAMINANTS
NJ
VO
ISIS
Code
No.
200
201
202
203
204
205
206
207
Grade
No. 1 Heavy
Melting
No. 1 Heavy
Melting
No. 1 Heavy
Melting
No. 2 Heavy
Melting
No. 2 Heavy
Melting
No. 2 Heavy
Melting
No. 2 Heavy
Melting
No. 1 Busheling
Thickness
6 mm-plus
(l/4"-plus)
6 mm— plus
(1/4" -plus)
6 mm-plus
(l/4"-plus)
3 mm-plus
(l/8"-plus)
—
—
—
-
Density
Bundle or Kg/cu. m.
Piece Size .(lb/cu.ft.
P 150 x 60cm
(P 60 x 24")
P 90 x 45cm
P 36 x 18"
P 150 x 45cm
(P 60 x 18")
Chg. Box
P 45 x 90cm
(P 18 x 36")
P 90 x 45cm
(P 36 x 18")
P 150 x 45cm
(P 60 x 18")
30cm sq.
(12" sq.)
Contaminants
Other
) Zinc Lead Tin Coatings Sources
THESE
CONTAMINANTS
NOT
PERMITTED
Galv. UNDER
THESE
Galv. Prepared Auto Scrap
SPECIFICATIONS
Galv. Prepared Auto Scrap
(Free of sheet iron
or thin gauge tnat'l)
Galv. Prepared Auto Scrap
(Free of sheet iron
or thin gauge mat'l)
No No No No New factory bushels.
No auto or fender
208 No. 1 Bundles
Sheets
Chg. Box
1200 Kg/cu.m No
[75 (min.)]
No Chem.
Detinned
No
stock
No auto or fender
stock
-------
TABLE 5. (CONTINUED)
ISIS
Code
No. Grade
209 No. 2 Bundles
210 Shredded Scrap
211 Shredded Scrap
212 Shredded
Clippings
213 Shredded Tin Cans
214 No. 3 Bundles
215 Incinerator
Bundles
216 Terne Plate
Bundles
217 Bundled No. 1
218 Bundled No. 2
219 Machine Shop
Turnings
Density
Contaminants
Bundle or
Thickness Piece Size
Sheets Chg. Box
-
-
Sheets
-
Sheets Chg. Box
Chg. Box
Sheets Chg. Box
3 mm-plus Chg. Box
(l/8"-plus)
3 nun-plus Chg. Box
(l/8"-plus)
Kg/cu.m.
(Ib/cu.ft.)
1200 Kg/cu.m
[75 (min.)]
800 Kg/cu.m
[50 (avg.)]
1100 Kg/cu.m
[70 (avg.)]
950 Kg/cu.m
[60 (avg.)]
-
1200 Kg/cu.m
[75 (min.)]
1200 Kg/cu.m
[75 (min.)]
1200 Kg/cu.m
[75 (tain.)]
1200 Kg/cu.m
[75 (min.)]
1200 Kg/cu.m
[75 (min.)]
Zinc Lead Tin
Galv. No No
Other
Coatings
No
From Auto Bodies
From Auto Bodies
_
Solder Tin or
TFS
No Restrictions
Solder Tin
Lead
No No No
-
Al Tops
No Cans
Whatsoever
Al?
-
No
From Auto Body, Chassis,
Driveshaf ts , and Bumpers
Sources
-
Autos ; Unprepared
Nos. 1 & 2 steel
Autos ; Unprepared
Nos. 1 & 2 steel
-
-
Incinerated Tin
Cans
-
No. 1 Steel
60% Auto &
Fender Stock
Machine Shop
(No Iron Borings)
-------
TABLE 5. (CONTINUED)
ISIS
Code
No.
220
221
222
223
224
225
226
227
228
Density
Bundle or Kg/cu. m.
Grade Thickness Piece Size (Ib/cu.ft.)
Machine Shop - -
Turnings & Iron
Borings
Shoveling -
Turnings
Shoveling - - -
Turnings & Iron
Borings
Iron Borings - -
Auto Slabs - P 90 x 45cm
(P 36 x 18")
Auto Slabs - P 60 x 45cm
(P 24 x 18")
Briquetted
Iron Borings
Briquetted
Steel Turnings
Mill Scale - -
Contaminants
Other
Zinc Lead Tin Coatings Sources
- - - - Machine Shop
- Free of Machine Shop (No Iron
Excess Borings)
Oil
- - - Free of Machine Shop
Excess
Oil
- - - " Machine Shop
From Auto Bodies Automobiles
From Auto Bodies Automobiles
"Analysis and density to
consumer's specifications"
"Analysis and density to
consumer's specifications"
- - - Magnetic
-------
TABLE 6. ISIS SCRAP SPECIFICATIONS AND COMMENTARY
ISIS* Specifications for Basic Open
Ho o, »-«-V.
T?~\ or* f-yf r*
Furnace, and Blast Furnace Grades
ISIS 200 No. 1 heavy melting steel.
Wrought iron and/or steel
scrap 1/4 inch and over in
thickness. Individual pieces
not over 60 x 24 inches
(charging box size) prepared
in a manner to insure compact
charging.
ISIS 201 No. 1 heavy melting steel
3 feet x 18 inches. Wrought
iron and/or steel scrap 1/4
inch and over in thickness.
Individual pieces not over
36 inches x 18 inches
(charging box size) prepared
in a manner to insure compact
charging.
ISIS 202 No. 1 heavy melting steel 5
feet x 18 inches. Wrought
iron and/or steel scrap 1/4
inch and over in thickness.
Individual pieces not over
60 inches x 18 inches
(charging box size) prepared
in a manner to insure compact
charging.
Commentary
ISIS 200
ISIS 201; 202
The only possible source of
charging fume from scrap which
adheres to this specification
is from the reaction of iron
oxide or paint on the scrap
which reacts to form fume when
hot metal is poured over it.
Same remarks as 200. The
different size alone should
not effect charging fumes.
^Institute of Scrap Iron and Steel
-------
TABLE 6. (CONTINUED)
ISIS* Specifications for Basic Open
Hearth, Basic Oxygen, Electric
Furnace, and Blast Furnace Grades
ISIS 203 No. 2 heavy melting steel.*
Wrought iron and steel scrap,
black and galvanized, 1/8
inch and over in thickness,
charging box size to include
material not suitable as No. 1
heavy melting steel. Prepared
in a manner to insure compact
charging.
ISIS 204 No. 2 heavy melting steel.**
Wrought iron and steel scrap,
black and galvanized, maximum
size 36 x 18 inches. May
include all automobile scrap
properly prepared.
Commentary
ISIS 203 This specification permits
galvanized scrap in apparently
unlimited proportions. In addition,
the thinner scrap permitted, 1/8
inch vs. 1/4 inch in ISIS grades
200 to 202 will result in a higher
proportion of zinc oxide fumes to be
emitted.
ISIS 204 This specification, like 203, permits
galvanize, but in addition, permits
automobile scrap when properly prepared.
This specification does not say so,
but is dependent upon the care with
which automotive scrap is prepared.
Whether galvanized, or terne (lead
alloy coating) is removed is of major
importance, as is the removal of paint,
undercoat material, electrical insula-
tion and non-metallic materials. From
a practical standpoint, it appears that
some of these fume producers will
remain on the scrap and cause fumes
upon charging or when hot metal is
charged.
*Institute of Scrap Iron and Steel
**The identical designations given for these two classifications are in accordance with established
industry practices in specifying the materials desired.
-------
TABLE 6. (CONTINUED)
ISIS* Specifications for Basic Open
Furnace, and Blast Furnace Grades
ISIS 206 No. 2 heavy melting steel
5 feet x 18 inches. Wrought
iron and steel scrap, black
and galvanized, maximum size
60 x 18 inches. May include
automobile scrap, properly
prepared, however, to be free
of sheet iron or thin gauged
material.
ISIS 207 No. 1 busheling. Clean steel
scrap, not exceeding 12 inches
^o in any dimensions, including
"p* new factory busheling (for
example, sheet clippings,
stampings, etc.). May not
include old auto body and
fender stock. Free of metal
coated, limed, vitreous enameled
and electrical sheet containing
over 0.5 percent silicon.
ISIS 208 No. 1 bundles. New black steel
sheet scrap, clippings or
skeleton scrap, compressed or
hand bundled, to charging box
size, and weighing not less
than 75 pounds per cubic foot.
(Hand bundles are tightly secured
Commentary
ISIS 206
ISIS 207
ISIS 208
Like 205, the specification permits
galvanized scrap, but is the same
as 205, in that it permits the same
type of scrap included in 205. The
only difference is in the dimension
of the bundles that is permitted.
This specification calls for clean
steel and excludes all auto body
and fender stock. The scrap must be
free of metal coated, limed, vitreous
enameled steel, and electrical sheet
containing more than 0.5% silicon.
These bundles are specified to
contain new black (uncoated)
sheet steel scrap. The only
relaxation in this specification
appears to be that it may include
chemically detinned material. It
specifically excludes old auto body
*Institute of Scrap Iron and Steel
-------
TABLE 6. (CONTINUED)
ISIS* Specifications for Basic Open
Hearth, Basic Oxygen, Electric
Furnace, and Blast Furnace Grades
for handling with a magnet). May
include Stanley balls or mandrel
wound bundles or skeleton reels,
tightly secured. May include
chemically detinned material.
May not include old auto body or
fender stock. Free of metal
coated, limed, vitreous enameled,
and electrical sheet containing
over 0.5 percent silicon.
ISIS 209 No. 2 bundles. Old black and
w galvanized steel sheet scrap,
01 hydraulically compressed to
charging box size and weighing
not less than 75 pounds per
cubic foot. May not include
tin or lead-coated material
or vitreous enameled material.
ISIS 210 Shredded Scrap. Homogeneous
iron and steel scrap, magnetically
separated, originating from
automobiles, unprepared No. 1
and No. 2 steel, miscellaneous
baling and sheet scrap. Average
density 50 pounds per cubic
foot.
*Institute of Scrap Iron and Steel
Commentary
or fender stock, metal coated,
vitreous enameled, and electric
sheet over 0.5% silicon.
ISIS 209 These No. 2 bundles can contain
old black uncoated iron and
galvanized sheet scrap, but
specifically excludes tinned or
lead-coated materials, as well
as vitreous enameled material.
ISIS 210 This shredded scrap must be magne-
tically separated (to remove non-
ferrous and non-metallic materials).
It is to be prepared from automobile
hulks and No. 1 and No. 2 steel, as
well as miscellaneous baling and
sheet scrap. Its density shall
average 50 pounds per cubic foot.
Its low density and high surface
area will permit large quantities
of fume producers.
-------
TABLE 6. (CONTINUED)
ISIS* Specifications for Basic Open
Hearch , Basic Oxygen, Electric
Furnace, and Blast Furnace Grades
Commentary
ISIS 211 Shredded Scrap. Homogeneous
iron and steel scrap magnetically
separated, originating from auto-
mobiles, unprepared No. 1 and
No. 2 steel, miscellaneous baling
and sheet scrap. Average density
70 pounds per cubic foot.
ISIS 212 Shredded Clippings. Shredded
1000 series carbon steel
clippings or sheets. Material
should have an average density of
60 pounds per cubic foot.
ISIS 213 Shredded Tin Cans for Remelting.
Shredded steel cans, tin coated
or tin free, may include
aluminum tops but must be free
of aluminum cans, non-ferrous
metals except those used in can
construction and non-metallics
of any kind.
ISIS 211 This shredded scrap differs
from 210 only in that its
average density shall be 70
pounds per cubic foot. It
should therefore cause less
fume than ISIS 210.
ISIS 212 Shredded clippings shall consist
purely of carbon steel
clippings or sheets with a
density of 60 pounds per cubic
foot. The limit to 1000 series
steels (non-alloy) has no effect
on fume.
ISIS 213 This specification differs from
212 in that tin coated or tin
free steel sheets can be included.
The aluminum tops on the tin cans
can be included, but not aluminum
cans. Non-ferrous metals, such
as the solder used in can con-
struction, is permitted.
*Institute of Scrap Iron and Steel
-------
TABLE 6. (CONTINUED)
ISIS* Specifications for Basic Open
Hearth, Basic Oxygen, Electric
Furnace, and Blast Furnace Grades
ISIS 214 No. 3 bundles. Old sheet steel,
compressed to charging box size
and weighing not less than 75
pounds per cubic foot. May
include all coated ferrous scrap
not suitable for inclusion in
No. 2 bundles.
ISIS 215 Incinerator bundles. Tin
can scrap, compressed to
charging box size and weighing
not less than 75 pounds per
cubic foot. Processed through
a recognized garbage incinerator.
ISIS 216 Terne plate bundles. New terne
plate sheet scrap, clippings or
skeleton scrap, compressed or
hand bundled, to charging box
size, and weighing not less than
75 pounds per cubic foot. (Hand
bundles are tightly secured for
handling with a magnet.) May
include Stanley balls or mandrel
wound bundles or skeleton reels,
tightly secured.
Commentary
ISIS 214 No. 3 bundles include old
sheet steel and permit all
coated ferrous scrap not suit-
able for inclusion in No. 2
bundles (ISIS 209). The old
material permits rust. The
permitted low density increases
the permissible surface contaminants,
ISIS 215 This specification calls for
tin can scrap compressed into
bundles after processing through
a garbage incinerator. It
probably does exclude terne
(lead) plate in large quantities.
ISIS 216 This specification permits
sheets coated with a lead-tin
alloy known as "terne." The
scrap it covers is also very
bulky.
*Institute of Scrap Iron and Steel
-------
TABLE 6. (CONTINUED)
OJ
00
ISIS* Specifications for Basic Open
Hearth, Basic Oxygen, Electric
Furnace, and Blast Furnace Grades
ISIS 217 Bundled No. 1 steel. Wrought
iron and/or steel scrap 1/8
inch or over in thickness,
compressed to charging box
size and weighing not less
than 75 pounds per cubic foot.
Free of all metal coated
material.
ISIS 218 Bundled No. 2 steel. Wrought
iron or steel scrap, black or
galvanized, 1/8 inch and over
in thickness, compressed to
charging box size and weighing
not less than 75 pounds per cubic
foot. Auto body and fender
stock, burnt or hand stripped,
may constitute a maximum of 60
percent by weight. (This percent
based on makeup of auto body,
chassis, driveshafts, and
bumpers.) Free of all coated
material, except as found on
automobiles.
Commentary
ISIS 217 The only known source of polluting
fume in steel adhering to this
specification is the mill scale
and rust on the scrap. The 1/8"
minimum thickness insures the
proportion of iron oxide will be
low.
ISIS 218 This specification permits heavy
gauge (1/8 inch) galvanize and
also any coated material that is
found in automobiles. In effect,
it permits tin, lead, organics,
oil, and tar to the extent they
appear in (unprepared) automobiles.
The 1/8 inch thickness does limit
the proportions of all coatings.
All in all, this material could
account for a high amount of
fugitive fume.
^Institute of Scrap Iron and Steel
-------
TABLE 6. (CONTINUED)
ISIS* Specifications for Basic Open
Hearth, Basic Oxygen, Electric
Furnace, and Blast Furnace Grades
ISIS 219 Machine shop turnings. Clean
steel or wrought iron turnings,
free of iron borings, non-
ferrous metals in a free
state, scale, or excessive
oil. May not include badly
rusted or corroded stock.
Commentary
LO
VD
ISIS 220 Machine shop turnings and
iron borings. Same as
machine shop turnings but
including iron borings.
ISIS 219 This specification has in
it several restrictions which,
to the extent followed, should
reduce fuming. It calls for
clean steel and excludes non-
ferrous metals, except for those
dissolved in the steel. On the
side of leniency, it permits oil,
if not "excessive" and rust, if
not "badly rusted."
ISIS 220 This grade can include iron
borings, but is otherwise the
same as ISIS 219. Its fuming
should not differ from that of
219.
ISIS 221 Shoveling turnings. Clean
short steel or wrought iron
turnings, drillings, or screw
cuttings. May include any such
material whether resulting from
crushing, raking, or other
processes. Free of springy,
bushy, tangled or matted material,
lumps, iron borings, non-ferrous
metals in a free state, scale,
grindings, or excessive oil.
ISIS 221 This specification differs from
ISIS 219 and 220 only in that
it excludes long, curly chips
that cannot be shoveled.
*Institute of Scrap Iron and Steel
-------
TABLE 6. (CONTINUED)
ISIS* Specifications for Basic Open
Hearth, Basic Oxygen, Electric
Furnace, and Blast Furnace Grades
Commentary
ISIS 222
ISIS 223
ISIS 224
ISIS 225
ISIS 226
Shoveling turnings and iron
borings. Same as shoveling
turnings, but including iron
borings.
Iron borings. Clean cast iron
or malleable iron borings and
drillings, free of steel
turnings, scale, lumps, and
excessive oil.
Auto slabs. Clean automobile
slabs, cut 3 feet x 18 inches
and under.
ISIS 222
ISIS 223
ISIS 224; 225
Auto slabs. Clean automobile
slabs, cut 2 feet x 18 inches
and under.
Briquetted iron borings.
Analysis and density to
consumer's specifications.
ISIS 226; 227
Includes iron borings not
permissible under ISIS 221.
This has a specific prohibition
against excessive oil, as well
as scale and lumps which might
be caused by oil or rust.
These two differ only as to
the size of the slab. The fume
they cause is completely
dependent on the degree of
preparation of the automobiles
before being compressed into slabs,
These specifications depend
upon the restrictions set up
between buyer and seller. Oil
is the major source of fume.
*Institute of Scrap Iron and Steel
-------
TABLE 6. (CONTINUED)
ISIS* Specifications for Basic Open
Hearth, Basic Oxygen, Electric
Furnace, and Blast Furnace Grades
ISIS 227 Briquetted steel turnings.
Analysis and density to
consumer's specifications.
ISIS 228 Mill scale. Dark colored,
ranging from blue to black,
ferro-magnetic iron oxide
forming on the surface of
steel articles during heating
and working.
Commentary
ISIS 228 Mill scale can cause fume
because of oil from the
mills and the reaction of
iron oxide with hot metal.
*Institute of Scrap Iron and Steel
-------
SECTION 7
INSTALLATIONS OF CHARGING EMISSION CONTROL SYSTEMS
A literature search was conducted for information on charging emission
control systems that have been installed. There were several brief
descriptions of equipment but data on effectiveness are meager. The
following descriptions of available information are in chronological order.
WISCONSIN STEEL WORKS - SOUTH CHICAGO, IL (1)*
This design incorporated smoke hoods over the charging area of each of
two 125 tonne (140 N.T.) vessels to collect fume evolved during charging.
The hoods, each about 2.4 meters (8 feet) square, are piped to lead the
collected gas through a common riser into the dirty gas main downstream from
the main vessel evaporation with valves so that gas is drawn only through
the individual hood over the vessel being charged. There is no drop-out
chamber in the circuit, so all the dust, regardless of size, goes to the
main system precipitator. No information on effectiveness has been published.
ALLEGHENY LUDLUM STEEL - NATRONA, PA (2)
The original design of this plant included a smoke hood on both sides of
each 73-tonne (80-ton) vessel to collect the fumes emitted during charging,
tapping, and reladling. The common exhaust from these auxiliary hoods is
connected to the dirty gas main downstream from the main evaporating chamber,
and ahead of the wet scrubber. The system handles 450 m-Vmin. (16,000 scfm)
of air and has no primary settling chamber.
GREAT LAKES STEEL - ECORSE, DETROIT, MI (3)
The 180-tonne (200-ton) furnaces in the No. 2 BOP shop of Great Lakes
Steel Division of National Steel Corporation have an auxiliary fume collection
hood over each vessel. The hoods are each connected to a vertical riser of
rectang;ular cross-section which in turn connects to the dirty gas main (which
collects the dirty gases from each furnace) leading to the electrostatic
precipitator. Flow through the auxiliary system is controlled by three air-
operatfid dampers to provide a draft induced by the precipitator I.D. fans on
the furnace being charged. There are no drop-out chambers or primary
collectors in the system. Flow through one hood is 4200 m^/min. (150,000
scfm). A duct entrance 4-6 meters x 2.4 meters (15 ft. x 7.9 ft.) was placed
*See references at the end of this section.
42
-------
3.0 meters (10 feet) above the vessel mouth. Entrance air was calculated by
the designer to have a velocity of 60 m/min. (200 fpm). Duct velocity of
2400 m/min. (8000 fpm) and a pressure drop of 30 cm (12 in.) water column
were calculated.
The system was moderately effective while in operation. However, the
system is currently inoperative due to explosions which occurred in the ducts
above the hood.
HOOGOVENS - IJMUIDEN, NETHERLANDS (4)
Plant No. 2 of Hoogovens/Estel, at Ijmuiden, Netherlands, has a shop
consisting of two 300 tonne (330 NT) vessels. One vessel has been equipped
with an experimental ventilation system. The data given on the system are as
follows:
Total surface of holes in
exhaust hood
Quantity of gas exhausted
Max. temp, of gas during
hot metal charging
Max. temp, of gas during
scrap charging
Energy consumption
Velocity in waste gas pipe
Fan draft
As Reported
(Metric)
2.5 m2
60,000 NM3/Hr
120°C
400°C
180 kw
15 m/s
480 mm W.G.
Converted
(English)
(27 sq.ft.)
(35,000 scfm)
(248°F)
(752°F)
(648 MJ)
(49 ft/sec)
19 inch water
column
Hoogovens reported trapping about half of the charging fumes. At the
time of the publication, the plant expected to install a permanent system in
order to further reduce the escape of charging fumes.
KRUPP SYSTEM (5)
A photograph showing a suction slot system with slot type hoods located
on either side of the charging emission area which was installed in Japan
appeared in this reference. No details were given but it was noted that the
system did not work satisfactorily.
LYKES-YOUNGSTOWN (YOUNGSTOWN SHEET & TUBE) - INDIANA HARBOR (6)
A charging fume collection system consisting of a rectangular hood over
each of two 260 tonne (290 ton) vessels was installed during construction in
43
-------
1970. The hoods are connected by ducts to a multi-clone collector and
exhaus': gases from the multi-clone feed through a drop-out chamber into the
main duct leading to the main gas cleaning precipitators. Each smoke hood
has a cross-sectional area of about 20 square meters (220 sq. ft.) and is
provided with a sliding gate shutoff so that the gas flow of 4200 m-Ymin.
(150,000 scfm) can all be channeled through the hood over the vessel being
charged.
U.S. STEEL CORPORATION - LORAIN, OH (7)
A brief mention was made of an auxiliary ventilation system for charging
emissians but details of the installation and effectiveness were not dis-
cussed.
BRITIST STEEL CORPORATION (8)
The British Steel Corporation has-done a considerable amount of testing
and research concerning control of charging fumes which included electrical
analog and cold model studies. Based on these studies ideal requirements
for extraction hoods for 250-300 tonne (275-330 NT) vessels were developed:
1. A hood should be placed close to the source of fume and, if possible,
directly above it,
2. The hood system should be able to operate in an up-flow of hot gas at
3-4 m/s (600-800 fpm) and
3. The extracted volume capacity should be 100-200 m3/sec (210,000-420,000
cfm).
Installation of a relatively small hood directly above the charging area
which would theoretically capture 75 to 90% of the emissions and a second
hood s.bove the overhead crane which would capture the remaining emissions was
suggested. There is no published information about an actual installation.
CALDERON SYSTEM (9)
A sketch of the Calderon control system which is essentially a large
hood located in the emission area connected through a damper to the main hood
is shown in this reference. No details were given.
FORD MOTOR COMPANY, DEARBORN, MI (10, 11)
A method of control was developed at Ford in conjunction with R. G. Gaw
who has obtained a patent on the system. The main hood is partially blocked
by a sliding damper which increases the velocity in the charging emission
area i:hereby increasing effectiveness of the primary hood system. Four tests
of the system showed promising results and Ford decided to install a
permanent system. No results have been reported to date.
Mr. Gaw reported that several other companies are evaluating the system
but no results have yet been published.
44
-------
INLAND STEEL COMPANY, INDIANA HARBOR WORKS (12, 13)
Inland Steel recently installed a new BOP shop with two 190 tonne (210
ton) vessels. A charging emission control hood is located above the charging
area and is connected to a 5400 m3/min. (190,000 cfm) exhaust system. A
chain curtain is employed to increase effectiveness. An 11,000 m-Vmin.
(400,000 cfm) charging aisle roof canopy system was also installed.
U.S. STEEL, FAIRFIELD WORKS (14)
U.S. Steel installed a secondary fume collection system at the Q-BOP shop
which is a hood located over the charging area connected with dampers to the
primary system. Eighty percent of the available fan capacity of the primary
system can be utilized in the secondary hood. According to this reference,
up to 95% collection of secondary emissions was obtained.
BAUMCO/PEC SYSTEM (15, 16)
A system developed by Baumco consists of an enclosed vessel and
secondary hood located over the charging area which is connected to the main
exhaust system. It is claimed that 90% of the emissions can be captured
provided that the hot metal charging time is not less than 2 minutes and that
the scrap contains little or no oil.
FRIED KRUPP HUTTENWERKE AG, RHEINHAUSEN WORKS (17)
The Baumco suppressed combustion system with vessel enclosure and
secondary hood (see above) was installed at the two 350 tonne (385 ton)
vessel Rheinhausen Works. The primary exhaust system, to which the secondary
hood is connected, has a rating of 8300 m3/min. (290,000 cfm). Effectiveness
was not discussed.
STEEL COMPANY OF CANADA, HAMILTON, ONTARIO (18)
Stelco evaluated effectiveness of side draft hoods located directly
above the charging area of their three 113 tonne (125 ton) vessels. Three
gas handling systems were investigated. The first system was a baghouse
rated at 3000 m3/min. (105,000 cfm) at 121°C (250°F) and the design face
velocity was 250 m/min. (820 ft/min.). High temperature failure of the bags
occurred and the baghouse system was replaced with a multi-clone dust
collector which was connected to the inlet header of the main gas cleaning
system (precipitators). The hoods were enlarged and repiped and the design
capacity of the second system was 4300 m3/min. (150,000 ft3/min.) at 260°C
(500°F). Design face velocity was 177 m/min. (580 ft/min.). Sintered dust
built up on the collector outlet tubes and lumps of dust falling from these
tubes blocked the cyclone collector tubes causing a drastic reduction in gas
flow. Several explosions related to the reduced flow were encountered and
the system was taken out of service to ensure safe operations.
For the third trial the ducts were enlarged, an induced draft fan was
installed to provide adequate draft under all conditions and a six cell
polyclone separator was included for kish removal prior to the induced draft
45
-------
fan. Rated capacity was 6100 m3/min. (216,000 ft3/min.) at 315°C (600°F) and
design face velocity was 256 m/min. (256 ft/min.). Twenty tests were
carried out during the Fall of 1976 and the estimated capture ranged from
65% for dirty scrap charges to 95% for clean scrap charges. Sudden changes
in pressure that occurred when hood isolation valves were closed and rapid
cyclic temperature changes resulted in failure of the ducts. The ducts are
being rebuilt and the valving is being modified to minimize sudden pressure
changes.
SUMMARY
Information on fourteen charging emission control systems was reported
in the literature. Twelve of these were auxiliary hoods located in the
emission area. The main difference among hood installations were size and
location which were dictated by individual shop configuration and the type of
gas removal and cleaning equipment. Some shops had separate gas removal
systems and others connected into the primary vessel emission control system.
Only four of the hood systems were reported as having a reasonable degree of
success - Inland Steel, Fairfield Works of U.S. Steel, Stelco, and the Baumco
system. No data were presented to substantiate the successful claims.
It is apparent from the wide diversity of hood configurations the lack
of data on many systems and the lack of support data for the systems claimed
to be successful that a definitive conclusion about auxiliary hoods cannot be
made.
The closure plate system at Ford shows some promise but long term field
trials will be required to establish reliability and effectiveness in
day-to-day operations.
Slot hoods tried in Japan were not successful.
REFERENCES
1. Nickel, M. E., "At Wisconsin Steel Works, International Harvester Com-
pany," AIME Open Hearth Proceedings, 1965, pp. 131-135.
2. Shaw, R. B., "Basic Hot Blast Cupola-BOF Steelmaking," Iron and Steel
Engineer Yearbook, 1968, pp. 13-21.
3. Private communication from National Steel Corporation.
4. van der Poel, A. and van der Linden, G.A.C., "Combating Air Pollution in
LD Plant 2 at Hoogovens, Ijmuiden," ISI Conference Proceedings:
"Operation of Large BOF's," published by The Iron and Steel Institute
(London), 1971, pp. 36-43.
5. Urban, G. and Fillies, F., "The Krupp System," ISI Conference Proceedings
"Operation of Large BOF's," published by The Iron and Steel Institute
(London), 1971, pp. 14-25.
46
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6. Ekberg, Paul H., "Design and Initial Operation of Youngstown's BOF's at
Indiana Harbor," Iron and Steel Engineer Yearbook, 1972, pp. 83-89.
7. Ciukaj, T. V., "U.S. Steel's Newest BOP Shop at Lorain," Journal of
Metal, March, 1972, pp. 43-45.
8. Pilkington, S., "Collection of Secondary Fume in EOF Steelmaking," Metals
Society Meeting: "Engineering Aspects of Pollution Control," November,
1974, pp. 25-31.
9. Mattis, R. P., "An Evaluation of Charging and Tapping Emissions for the
Basic Oxygen Process," Presented at Air Pollution Control Association
Annual Meeting in Boston, Massachusetts, June 15-20, 1975.
10. Will, C., "Ford's Better Ideas for Environmental Control," AIME Open
Hearth Proceedings, 1975, pp. 491-498.
11. Gaw, R. G., "Containment of Dust and Fume from a Metallurgical Vessel,"
U.S. Patent 3,854,709.
12. Wozniak, E. H., "The Phaseout of No. 2 Open Hearth and the Design and
Startup of No. 2 Basic Oxygen Furnace," AIME Open Hearth Proceedings,
1975, pp. 318-346.
13. McCluskey, E. J., "Design Engineering of the OG Gas Cleaning System at
Inland's No. 2 EOF Shop," Iron and Steel Engineer, December, 1976,
pp. 53-59.
14. Pearce, J., "Q-BOP Steelmaking Developments," Iron and Steel Engineer
Yearbook, 1975, pp. 64-73.
15. Baum, J. P., "Gas Cleaning and Air Pollution Control for Iron and Steel
Processes," Iron and Steel Engineer, June, 1976, pp. 25-32.
16. Nicola, A. G., "Fugitive Emission Control in the Steel Industry," Iron
and Steel Engineer, July, 1976, pp. 25-30.
17. Kotsch, J. A., "The New L-D-Steel Shop at Fried Krupp Huttenwerke AG,
Gheinhausen Works," Iron and Steel Engineer, June, 1976, pp. 33-36.
18. D'Andrade, M. J., "Evaluation of BOF Charging Collection System," paper
presented at the Air Pollution Control Association Annual Meeting,
Toronto, Canada, June 20-June 24, 1977.
47
-------
SECTION 8
CHARACTERISTICS OF BOP CHARGING EMISSIONS
INTRODUCTION
Ds.ta suitable for design and engineering of BOP charging emission con-
trol systems are meager as indicated in previous sections of this report.
Therefore, emission sampling at the Weirton Steel Division of National Steel
Corporation BOP shop by TRW was conducted during the hot metal charging
operation to characterize the emissions, determine emission velocity and
volume and evaluate effects of scrap type and hot metal pouring time. Four
types of scrap ranging from poor quality No. 2 bundled scrap to clean, good
quality scrap were included in the scrap charge. Pouring times ranged from
32 to 98 seconds.
EMISSION SAMPLING EQUIPMENT
A sketch showing the BOP vessel, the main hood, the transfer ladle and
the saripling pipe is shown in Figure 9. The 325 tonne (360 tons) vessel had
a mouth opening of 3.7 meters (12 feet). A 150 mm (6 inch) diameter pipe was
located vertically at the vessel centerline as viewed from the charging side
of the vessel and was approximately 3.7 meters (12 feet) above the top of the
vessel. Distance from the vessel centerline toward the transfer ladle was
about 3.7 meters (12 feet). The sample pipe had a right angle bend about 2
meters (6 feet) above the open end and a horizontal run of 9 meters (30 feet)
to a c^.ear space on the service floor where the sampling equipment was
located.
F:.gure 10 shows the sampling train with four sample taps. The first
sample;: in line was for particle size determinations with a Brink Model B
cascade impactor operated at a fixed pressure drop. The sample impactor discs
and filter were removed after each heat and the obtained samples were dried
and weighed with standard procedures.
Mass determinations were obtained by extracting a sample through a
nozzle into a filter holder containing a glass fiber filter. Gas volume was
measured with a Rockwell 175-S air test meter, a standard EPA-type particu-
late sampling train meter. The particulate from the filter was dried and
weighed with standard laboratory procedures. A silica gel sampling tube was
employed in this sampling train to obtain gas moisture by measuring weight
gain of the gel during exposure to the measured gas volume.
48
-------
Gas samples were obtained by aspiration into evacuated bags. Sulfur
dioxide was measured with EPA method No. 6 wherein the sample is absorbed in
hydrogen peroxide and titrated. Gaseous hydrocarbons were measured with a
flame ionization detector equipped gas chromatograph. Carbon monoxide,
carbon dioxide and oxygen were measured with a gas chromatograph for the
first four tests and with a standard laboratory model Orsat analyzer for the
remaining tests. Nitrogen content was determined by difference.
Particulate samples for chemical analysis were obtained with a high
volume sampler and analyzed for C, Fe, FeO, Fe2C>3, CaO, MgO, Si02, A1203,
SO^, Na20, K20, PbO, ZnO and MnO by standard atomic absorption techniques.
In addition, particulate samples from the size determinations were analyzed
by spark source mass spectrometry, by Northrup Company under a separate EPA
contract.
VELOCITY AND PLUME SIZE MEASUREMENTS
Attempts to measure emission gas velocity with a hand held type S pilot
tube were unsuccessful because the heat in the sampling location caused the
tube to bend. The pilot tube apparatus contained a thermocouple for plume
temperature measurements but the number of tests was limited because of the
apparatus failure.
High speed motion pictures were taken by EPA photographers of many of the
heats. Frame rate was 100 frames per second, four times normal speed. The
pictures were examined frame by frame and measurements of plume location were
made on many individual emission plumes. Velocities were calculated from the
measured change in plume location from frame to frame and the known interval
between frames.
Emission volumetric rate was calculated from the measured velocities
and an estimate of the plume size with the assumption that the plume was
circular in shape.
CHARGE MATERIALS
The scrap charges were classified by the types of contaminated scrap
charged. Three types of contaminated scrap were involved: galvanized sheet
scrap, oily turnings and No. 2 bundles. The rest of the scrap charge was
clean scrap consisting mostly of No. 1 bundles; No. 1 heavy melting; slab,
bloom and ingot butts and return scrap from in-plant operations. No attempt
was made to evaluate the various types of clean scrap involved because of the
limited number of tests. The amount of contaminated scrap charged in each
case was the maximum that operating personnel would permit based on vessel
operating characteristics, steel chemistry specifications and final product
quality requirements.
Table 7 shows the amounts of each scrap employed for each test heat
expressed as the percentage of metallic charge. Six heats were made with no
contaminated scrap. Three heats were made with galvanized scrap charges
ranging from 1.2 to 1.9%. Oily compacted turnings were charged to three
heats in amounts ranging from 0.7 to 1.3%. Three heats were charged with
49
-------
from 4.9 to 5.8% No. 2 bundles; two of these also had some oily turnings
charged but the amount was small in comparison to the amount of No. 2 bundles.
Total scrap charge, the sum of the contaminated scrap and clean scrap, ranged
from 32.5 to 37.1%.
The balance of the charge was hot metal with an average chemistry of
1.21% Si, 0.80% Mn, 0.039% S and 0.075% P. The range observed for each
element was within normal variations. Hot metal temperature averaged 1374°C
(2506°B) and ranged from 1338°C (2440°F) to 1416°C (2580°F), a typical
variation.
HOT METAL CHARGING TIME
Charging times ranged from 32 to 98 seconds as shown in Table 7. An
attempt was intentionally made during hot metal charging of the six heats with
all clean scrap to obtain a range of charging times. The shortest was 32
seconds and the longest was 63 seconds. Longer times were not obtained
because productivity would have been lowered. No control of charging time
was exercised for the contaminated scrap heats other than the normal procedure
employed by the charging crane operator who charged at a rate depending upon
the amount of emissions evolved and the condition of the scrap; the trials
were conducted in mid-winter and charges which might have contained ice and
snow were charged slower.
DISCUSSION OF RESULTS
Details of the particulate emission characteristics are shown in Tables
8, 9 and 10. Table 11 shows the gaseous emission test results.
Clean £ crap Charges
The particulate sampler did not function properly for one of the six
tests. The range of particulate median diameter for the other five tests was
quite large, from 1.8 to 60 microns. Three of the heats were quite similar
with an average mean particulate size of 2.0 microns. One heat exhibited a
median diameter twice as large, 6.3 microns, and test No. 6 was 30 times as
large, 60 microns. There was no apparent correlation between particle size
and hot: metal pouring rate. A thorough review of the scrap types, hot metal
variables, etc. did not indicate any variable particular to the heat exhibiting
the large particle size.
Dust loading ranged from 2.1 gm/m3 (0.9 gr/ft3) to 21.7 gm/m3 (9.5
gr/ft3). There were no correlations between dust loading and pouring rate or
other rieasured variables.
Chemical analyses of the particulate samples obtained with the high
volume sampler, Table 9, showed that a significant amount of carbon, 34.3%,
was present in the samples. It was assumed from the sample appearance that
the carbon was present as kish. Major constituents were 34.3% C, 13.1% Fe,
12.7% l-'eO, 8.3% Fe203, 3.5% CaO, 1.0% MgO, 5.2% Si02, 2.2% A1203, and 3.4%
ZnO.
50
-------
Spark source mass spectrometry results of particulate samples from the
size determination tests are summarized in Table 10 (See Appendix A for de-
tailed results). Inconsistent variabilities were observed which are probably
related to the small size of samples, 0.005 to 2.2 mg.
Analysis of gas samples from the plume showed no CO, a small amount of
(X>2 ranging from a trace to 2.3% and the balance was 02 and N£ in proportions
indicating air dilution. Moisture content ranged from 0.6 to 17.4% and was
not related to process variables. Sulfur dioxide levels were quite low,
below 1.7%. Hydrocarbons were also low; gaseous methane averaged 9.9 ppm and
particulate hexane averaged 9 ppm.
Galvanized Steel Scrap Charges
Three heats were made with an average galvanized steel scrap charge of
1.6%. Dust loadings ranged from 3.7 gm/m3 (2.9 gr/ft3) to 12.4 gr/m3 (5.4
gr/ft3) which were within the range observed for the clean scrap heats.
Particle median diameter ranged from 1.3 to 3.3 microns which was also similar
to the clean scrap heats. There was a change in the particulate emission
chemical composition; the ZnO increased, as expected, from 3.4% average to
5.3% average and the iron oxide content was lowered. It appears that the
Zn reacted preferentially and suppressed iron oxidation. Later tests
described below did not substantiate this observation, however.
An increase in particulate hexane extractables was observed. Offgas
composition appeared to be similar to the clean scrap heats.
Oily Turnings Scrap Charges
The three heats with compressed oil turnings in the scrap charge
exhibited a significant increase in dust loading from an average of 10.2 gr/m3
for the clean heats to 26.8 gr/m3. Particle size was about the same.
Particulate chemical composition changed interestingly. The ZnO increased
to a level higher than observed for the galvanized scrap heats and the PbO
increased from 0.3% to 0.8% but the iron oxides were not lower as observed
with the high ZnO containing dust from the galvanized scrap heats. The
turnings must have contained high Zn and Pb contents. It is possible that
the Zn and Pb were oxidized prior to charging in the vessel which would
explain why the FeO content was not affected but this was not confirmed.
Gaseous methane increased significantly from 9.9 ppm average to 60.5 ppm
as expected. Particulate hexane extractables was about the same as for the
galvanized scrap heats. A small increase in gas CO and C02 contents was noted.
No. 2 Bundle Scrap Charges
The three heats with No. 2 bundle scrap charges had widely varying dust
loadings, from 8.2 to 490.5 gm/m3. The latter sample was not representative,
however, because it contained a single very large piece of material.
Particle sizing samples unfortunately were not obtained on two of the heats;
the other heat exhibited a particle sizing typical for the previous heats.
ZnO and PbO contents of the dust were the highest observed during the study,
51
-------
12.0% aid 1.8%, respectively. Iron oxides were about the same as for the
clean aid oily scrap heats. Hydrocarbons were similar to the oily scrap
heats with a slight increase in particulate hexane. The gas composition
showed the highest CO and C02 contents and the lowest 02 indicating that the
dirty szrap contained combustibles.
Velocity Measurements
Velocity measurements were made from the motion pictures and a large
variation in the velocity existed between different time intervals after the
start of the hot metal pour and between different heats. Four velocity
determinations on the same heat at the approximate same location but at
differe-.it times, for example, showed velocities of 900 m/min. , 1200 m/min. ,
450 m/m:Ln. and 1100 m/min. There was a trend of a decrease in the velocity
as a "smoke puff" ascended from the vessel mouth but this trend was small.
It was not possible to correlate velocity with scrap type or other
operating variables because the wide range of velocities measured during
individual heats was greater than the effects of these variables.
Average velocity from all measurements was 900 m/min. (2950 fpm). The
lowest isingle value was 300 m/min. (1000 fpm) and the highest was 1600 m/min.
(5200 fpm).
Charging Emission Volumetric Emission Rate
Charging emission volumetric emission rate was calculated from the
velocity measurements and the plume size which was measured from the motion
picture;;. It was assumed that the plume was symmetrical; this is not entirely
correct because of physical restraints such as beams and hood projections but
is satisfactory considering the velocity variability.
Vismal observations during the tests confirmed the plume measurements
from the films.
The average plume diameter was 4.6 m (15 feet). Average volumetric
emission rate was calculated to be 14,800 m3/min. (520,000 ACFM) and ranged
from 4900 m3/min. (170,000 ACFM) to 26,300 m3/min. (930,000 ACFM).
Charging Emission Temperature
Teriperature measurements were incomplete because of equipment failures
but several measurements indicated maximum temperatures of 816°C (1500°F).
Statistical Analysis
Thei test data presented in Tables 7 through 11 were statistically
analyzed at the University of Dayton under the auspices of the Environmental
Protection Agency. (See Appendix B for the complete analysis.) The results
were in general inconclusive. The largest correlation was 0.414 for a
relationship between grain loading and the amount of test scrap in the charge.
It was r.ot possible to determine if grain loading was related to scrap type
52
-------
because the amount of test scrap varied concurrently with the scrap type.
Correlations between particulate emission composition and scrap type
described in previous sections were confirmed but it was not possible to
separate effects of scrap type and the amount of contaminated scrap charged.
The general conclusion was that more tests should be run to obtain
sufficient data for a meaningful statistical analysis.
CONCLUSIONS
Emissions during hot metal charging of a full size BOP vessel were quite
variable. Some effects of scrap type were noted but significant correlations
between emissions and operating variables such as pouring time, hot metal
chemistry, hot metal temperature, percent scrap in the charge etc. were not
observed. The small range of variables investigated and the relatively
small number of observations precluded development of meaningful correlations,
It was found that particulate emissions from heats charged with clean
scrap had an average dust loading of 10.2 gm/m^ (4.5 gr/ft^) and that the
average particulate mean diameter was 15 microns. The average chemical com-
position was 34.3% C, 13.1% Fe, 12.7% FeO, 8.3% Fe203, 3.5% CaO, 1.0% MgO,
5.2% Si02, 2.2% A1203,' and 3.4% ZnO. Gas samples showed no CO, a small
amount of C02 and the balance 02 and N2- Sulfur dioxide and hydrocarbons
were low.
Including galvanized steel scrap in the charge resulted in an increase
in the particulate emission ZnO content, a decrease in iron oxides and no
change in dust loading.
Heats with oily turnings exhibited an increase in dust loading, greater
amounts of ZnO and PbO in the particulate, increased methane in the gas and
a small increase in gas CO and C02 contents.
Inclusion of No. 2 bundles resulted in a wide variation in dust loading.
Increases in dust ZnO and PbO content, particulate hydrocarbons and gas CO
and C02 contents were observed.
Average measured emission velocity was 900 m/min. (2950 fpm) but varied
widely from 300 m/min. to 1600 m/min. Calculated volumetric emission rate
was 14,800 m^/min. average (520,000 ACFM). Temperature measurements
indicated maximum plume temperatures of 816°C (1500°F).
53
-------
TABLE 7. FULL SIZE BOP TESTS - CHARGING MATERIALS
% of Metallic
Scrap lest
Type No .
Clean 1
2
3
" 4
5
6
Galv. 1
" 2
3
Oily 1
2
3
No. 2 Bundles 1
2
3
ulean
Scrap
36.4
35.0
33.8
35.0
35.4
35.8
35.0
34.8
33.1
32.3
32.3
32.6
30.5
27.6
31.3
Charge
Contaminated
Scrap
1.
1.
1.
0.
1.
1.
5.
4.
5.
0
0
0
0
0
0
2
9
8
7
3
3
1
9
8
Total
36.4
35.0
33.8
35.0
35.4
35.8
36.2
36.7
34.9
33.0
33.6
33.9
35.6
32.5
37.1
Charging
-L J. UtC ,
sec.
32
36
52
57
62
63
36
98
69
48
51
36
64
46
46
Co
Si
1.52
.94
.94
.95
1.08
1.22
1.27
1.42
1.28
1.45
1.21
.68
1.53
1.23
1.37
mpuo-i-
Mn
.85
.79
.77
.75
.85
.84
.84
.86
.82
.69
.76
.74
.78
.74
.86
Hot
t_ j_-_.n ,
S
.033
.045
.043
.037
.035
.039
.033
.040
.036
.058
.041
.040
.033
.038
.034
Metal
V
to
p
.090
.088
.074
.078
.087
.093
.093
.098
-
.070
.069
.069
.072
.066
.080
Ter.p
°F
2490
2480
2490
2500
2580
2550
2475
2590
2570
2440
2490
2445
2535
2450
2500
• J
°C
1365
1360
1365
1371
1416
1399
1357
1421
1410
1338
1365
1340
1391
1343
1371
Average
35.0
53
1.21 .80 .039 .075
2506 1374
-------
TABLE 8. FULL SIZE BOP TESTS - PARTICULATE EMISSION CHARACTERISTICS
Cumulative Weight Percent
Less than Stated Size
Scrap
Type
Clean
ii
ii
ii
"
"
Galv.
ii
"
Oily
"
ii
No. 2 Bundles
"
ii
Test
No.
1
2
3
4
5
6
1
2
3
1
2
3
1
2
3
Particle Diameter, microns
3.40
40
-
63
57
66
16
54
74
72
71
-
64
_
48
-
2.00
24
—
59
33
56
13
35
63
59
54
-
48
__
31
—
1.36
17
-
55
31
50
9
23
30
53
44
-
32
_
25
-
0.69
15
-
29
26
25
7
13
15
37
34
-
10
_
7
-
0.42
12
-
13
12
11
7
9
8
21
27
-
5
_
1
-
Median
Diameter,
Microns
6.3
-
1.7
2.6
1.8
6.0
3.3
1.8
1.3
1.4
-
2.3
_
3.1
-
Dust Loading
grams
m3
6.6
11.7
21.7
2.1
15.8
3.4
3.7
12.4
4.1
23.6
29.8
27.0
490.5*
8.2
41.4
grains
ft3
2.9
5.1
9.5
0.9
6.9
1.5
1.6
5.4
1.8
10.3
13.0
11.8
214.4*
3.6
18.1
*A very large single piece of material was observed in this sample which was
not representative but must be considered in the test results.
-------
TABLE 9. FULL SIZE BOP TESTS - CHEMICAL COMPOSITION OF PARTICIPATE EMISSIONS
No.
Scrap Test
Type No.
Clean I
2
3
4
5
6
" avg.
Galv. I
2
3
" avg.
Oily 1
2
3
" avg.
2 Bundles 1
n 2
3
" avg.
verage avg.
Composition, %
t'e.
8.3
15.5
18.4
17.6
10.7
8.2
13.1
7.7
0.9
1.2
3.3
13.0
3.1
17.9
11.3
0.4
8.2
2.9
3.8
8.9
*'eO
21.2
23.9
9.8
7.0
5.5
8.6
12.7
11.6
5.7
7.7
8.3
24.5
16.1
9.5
16.7
9.9
20.9
22.1
17.6
13.6
j.-e2U3
8.7
16.7
9.4
0.9
6.3
7.6
8.3
11.3
18.7
8.0
12.7
13.3
12.9
5.6
10.6
13.9
10.0
7.6
10.5
10.0
CaO
5.5
3.4
3.8
3.1
2.5
2.9
3.5
2.5
1.5
2.1
2.0
4.1
1.8
2.8
2.9
1.3
1.7
2.1
1.7
2.7
MgO
1.5
1.4
0.8
1.2
0.7
0.7
1.0
0.5
0.3
0.7
0.5
1.0
0.5
0.5
0.7
0.3
0.5
0.6
0.5
0.7
5102
5.1
4.1
6.0
5.5
7.9
2.7
5.2
2.9
2.7
2.3
2.6
2.6
2.9
3.4
3.0
1.9
3.5
3.0
2.8
3.8
Al20j 504
2.1 <.01
2.8 <.01
1.9 <.01
2.3 <.01
1.7 <.01
2.1 <.01
2.2 <.01
1.9 <.01
1.7 <.01
1.5 <.01
1.7 <.01
2.1 <.01
1.9 <.01
2.3 0.17
2.1 .06
1.9 0.29
2.1 0.17
2.3 <.01
2.1 .15
2.0 .04
Na2()
0.4
0.1
0.4
0.5
0.3
0.1
0.3
<.!
0.1
0.1
0.1
0.1
0.1
<0.1
0.1
0.1
0.3
0.1
0.2
0.2
K/0
0.2
0.1
0.5
0.1
0.1
<.l
0.2
<.l
0.1
0.1
0.1
0.1
0.1
0.2
0.1
0.1
0.2
0.1
0.1
0.1
FuG
0.4
0.3
0.4
0.3
0.3
0.1
0.3
0.1
0.2
0.2
0.2
0.9
1.0
0.6
0.8
1.9
1.8
1.8
1.8
2.3
ZnG
6.3
4.7
2.4
1.4
2.0
1.5
3.4
4.7
2.5
8.6
5.3
9.0
7.6
7.8
8.1
12.1
10.2
13.6
12.0
6.4
i-iiiw
0.8
0.8
0.5
0.3
0.4
0.3
0.5
0.4
0.3
0.3
0.3
0.8
0.5
0.5
0.6
0.5
0.5
0.9
0.6
0.5
c
32.3
4.0
28.8
35.5
54.4
50.8
34.3
47.4
60.6
72.9
60.3
31.8
45.9
35.7
37.8
52.9
34.0
37.5
41.5
41.6
-------
TABLE 10. FULL SIZE BOP TESTS - CHEMICAL COMPOSITION OF PARTICIPATE EMISSIONS*
Particle
Scrap Type Test No. Diameter, Microns
Composition, %
Ul
••o
Clean
Clean
Clean
Clean
Clean
Clean
Clean
Clean
Clean
Clean
Clean
Clean
Clean
Clean
Clean
Clean
Clean
Clean
Clean
Clean
Clean
Clean
1 2.00 to 3.40
1 1.36 to 2.00
1 .69 to 1.36
1 .42 to .69
1 0 to .42
3 2.00 to 3.40
3 1.36 to 2.00
3 .69 to 1.36
3 .42 to .69
3 0 to .42
4 2.00 to 3.40
4 1.36 to 2.00
4 .69 to 1.36
4 .42 to .69
4 0 to .42
5 2.00 to 3.40
5 1.36 to 2.00
5 .69 to 1.36
5 .42 to .69
5 0 to .42
Na Mg
0.1 1.7
No Sample
3.0 5.0
4.0 7.4
No Sample
No Sample
No Sample
9.8 6.9
3.7 16.8
1.9 2.2
<1.1 4.3
No Sample
No Sample
No Sample
2.7 4.4
0.8 2.0
<0.1 0.1
1.1 2.8
0.7 7.3
0.3 2.2
0.1 4.1
Si
1.
14.
9.
30.
19.
5.
4.
5.
5.
0.
3.
7.
-
2.
6
3
0
8
3
5
1
3
3
7
8
0
8
•
0
1
2
2
0
0
1
1
0
0
0
0
0
K
09
.6
.4
.2
.7
.4
.3
.2
.1
.1
.4
.2
.2
.1
Ca
0.9
5.4
0.7
3.5
3.1
1.0
2.6
0.5
0.4
0.4
2.9
4.3
1.9
1.6
Mn
0.
1.
1.
0.
1.
0.
0.
0.
0.
0.
0.
0.
0.
0.
3
6
5
4
0
3
1
6
5
1
4
3
3
1
Fe
3.
17.
16.
21.
18.
5.
3.
14.
12.
1.
9.
6.
20.
3.
1
8
8
5
6
9
1
1
8
3
2
0
6
2
Zn
0.8
3.4
6.6
10.8
3.3
2.3
0.3
2.8
2.5
0.2
2.1
1.4
1.3
0.4
Pb
0.3
1.81
2.0
2.0
3.1
0.2
.1
0.5
0.5
0.1
0.8
0.5
0.5
0.1
*Samples from particulate size tests analyzed by point source mass spectrometry by
Northrup Company. See Appendix A.
-------
TABLE 10. (CONTINUED)
Particle Composition, %
Scrap lype Test No.
Galv. 1
Galv. 1
Galv. 1
Galv. 1
Galv. 1
Galv. 2
Galv. 3
Galv. 3
Galv. 3
Galv. 3
Galv. 3
» Oily 1
Oily 1
Oily 1
Oily 1
Oily 1
Oily 2
Oily 3
Oily 3
Oily 3
Oily 3
Oily 3
.amet
2.00
1.36
.69
.42
0
No
2.00
1.36
.69
.42
0
2.00
1.36
.69
.42
0
er?
to
to
to
to
to
Samj
to
to
to
to
to
to
to
to
to
to
No Samp]
2.00
1.36
.69
.42
0
to
to
to
to
to
Microns Na
3.40
2.00
1.36
.69
.42
3.40
2.00
1.36
.69
.42
3.40
2.00
1.36
.69
.42
3.40
2.00
1.36
.69
.42
0.4
<0.6
1.1
<1.1
<2.8
No
<0.4
<0.8
0.3
<0.3
0.2
<0.5
<0.9
<0.9
<1.3
1.7
<0.2
0.1
0.1
<0.5
Hg
1.1
1.3
5.9
<3.3
<8.2
Samples
2.0
3.8
1.2
1.8
1.4
2.0
3.7
<2.6
<3.8
1.9
<0.5
0.5
O.4
<1.5
Si
3.4
2.6
5.4
<1.6
<4.0
1.2
2.5
2.6
2.5
3.5
2.4
4.5
1.3
<1.8
5.7
0.3
0.4
O.I
0.6
K
0.3
0.3
0.5
0.2
0.8
0.1
0.3
0.2
0.2
0.2
0.2
0.2
0.2
0.5
0.4
0.03
0.2
0.1
0.2
Ca
0.8
0.3
0.7
O.4
<1.1
1.0
2.8
1.9
4.0
0.9
0.9
0.9
<0.4
<0.5
0.5
<0.1
0.1
<0.05
1.1
0.2
0.6
0.2
0.4
0.1
0.2
0.1
0.1
1.5
1.2
0.9
3.0
1.7
10.3
0.3
0.4
0.5
0.2
*Samples from particulate size tests analyzed by point source mass spectrotnetry by Northrup
Company. See Appendix A.
-------
TABLE 10. (CONTINUED)
Scrap Type Test No.
No. 2 Bundles 1
No.
No.
No.
No.
No.
2 Bundles
2 Bundles
2 Bundles
2 Bundles
2 Bundles
No. 2 Bundles
2
2
2
2
2
Particle
Diameter, Microns
No Samples
2.00 to 3.40
1.36 to 2.00
.69 to 1.36
.42 to .(
0 to .i
No Samples
Composition, %
Na M£
Si
K
Ca
Mn
Fe Zn
Pb
0 O.4
0 0.4
6 <3.3
9 <1.0
2 2.1
<1 0
3.1
<9.9
<2.9
<9.9
<0
<1
<4
<1
<4
.05
.5
.8
.4
.8
<0.03
0.4
0.2
<0.1
0.2
<0
0
<1
<0
-------
TABLE 11. FULL SIZE BOP TESTS - GASEOUS EMISSION CHARACTERISTICS
Clean
Galv.
Oily
No. 2 Bundles
Hydrocarbons
Test
No.
1
2
3
4
5
6
1
2
3
1
2
3
1
2
3
Gaseous
Methane,
ppm
13
12
6
12
5
6
13
58
108
21
38
12
.2
.2
-
.6
.0
.7
_
.5
-
.9
.8
.8
.8
.8
.5
Parfioulate
Hexane ,
Extractables S02,
ppm
12
12
12
10
12
14
12
15
15
15
8
.5
8
8
6
9
.5
.5
.5
.5
.5
Moisture,
ppm %
<1
<2
1
1
1
1
0
0
1
.8
.2
-
.3
-
.7
_
.2
-
_
.0
.9
_
.5
.1
1
17
0
1
1
2
12
1
1
2
3
11
14
5
17
.4
.4
.6
.2
.8
.8
.5
.1
.7
.3
.0
.7
.6
.3
.8
Composition, %
CO C02
0
0
0
0
0
0
6.35
0
6.9
0.45
.9
tr
.4
2.3
.1
02
21.9
19.
21.
21.
18.
20.5
5.5
.37
6.87
N2*
77.6
79.8
78.3
78.5
79.6
79.4
.88 20.2 79.1
0 2.5 17.5 80.0
1.43 .77 17.6 80.2
0.13 .73 19.2 79.9
7.6 80.6
19.3 80.3
7.7 78.6
*By Difference
-------
Sampling Pipe
Vessel Shown
at 25° Tilt
12'0"
3.6 ra
Figure 9. Sampling Position at Weirton Steel Division
61
-------
Sampling Pipe from BOP
i» i »
B
--O
£5
F
G Q_Q-^ J Q-*.
K
Code
B
C
D
E
F
G
H
I
J
K
Equipment Identification
Identification
Sampling Pump, Air Exhaust
Particle Size Determinations
Brink Model B Cascade Impactor
Mercury Manometer
Sampling Pump, Air Exhaust
Mass and Moisture Determinations
Glass Fiber Filter
Silica Gel Sampling Tube
Sampling Pump
Rockwell 175-S Air Test Meter
Gas Samples
Evacuated Bags for Samples
Sampling Pump
Particulate Samples
High Volume Particulate Sampler
Figure 10. Schematic of BOP Charging Emission Sampling System.
62
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SECTION 9
TESTS OF EMISSION CONTROL SYSTEMS WITH A PILOT VESSEL
INTRODUCTION
Installation of charging emission control systems for evaluation purposes
in operating BOP shops is often excessively expensive and generally
impractical because of shop physical limitations. A study was therefore
conducted on a .91 metric ton pilot unit BOP vessel designed expressly for
charging emission control experiments. Provisions were made during design
for installing various hoods and emission control systems. Instrumentation
for characterizing the emissions was installed to obtain data suitable for
utilization during design of full size control systems. Improved control of
charging materials and charging conditions was also obtained thus eliminating
many uncontrollable variables encountered in full size BOP shops.
Twenty heats were made for this study. A guide plan of the systems to be
studied was periodically reviewed and revised during the study to obtain the
maximum useful information from the limited number of tests.
Baseline conditions were established from four heats which were made
without any active emission control system.
The first control system tested was a slot-type hood located directly
above the furnace mouth. This type of system is most likely to be adaptable
to existing shops.
Six heats were made utilizing inert gas purging of the vessel prior to
and during hot metal charging to determine if the emissions could be
suppressed at their source.
The closure plate system recently patented by R. G. Gaw was evaluated
with two heats. In this system, the closure plate closes off part of the main
hood system increasing the off-take gas velocity in the charging emission
vicinity, resulting in an increase in the possibility of capture with the
existing BOP main hood system.
Large canopy-type hoods were investigated on two heats.
It was learned from the first experiments that excellent capture could be
obtained with the main hood system if the vessel tilt is restricted during
charging. Two heats were made to evaluate the possibility of pouring through
a hole in the hood thus permitting almost vertical vessel positioning.
63
-------
The last heat was made with a slow hot-metal charging rate.
IRON AND STEELMAKING PROCEDURE
Hoi: metal was prepared by melting pig iron in a 680 kg (1500 Ib.) capac-
ity electric arc furnace. Melting conditions were closely controlled to
minimize carbon oxidation. A neutral slag was employed and was removed by
raking and decanting just prior to tap. Carbon injection was employed for the
first three heats to insure a carbon content representative of hot metal; it
was found to be unnecessary and was discontinued. Hot metal analyses are
shown in Table 13 and the average analysis was 4.23% C, 1.41% Si, 0.98% Mn,
0.010% 13 and 0.12% P.
The range of each element was well within the range normally encountered
during full-size BOP operations.
Th2 hot metal was tapped into a 906 kg (2000 Ib.) capacity ladle fitted
with a snout to simulate a typical transfer ladle configuration. It was
found nacessary to add kish to the ladle immediately after tap and, therefore,
6.8 kg (15 Ibs.) of kish were added for heats 4 through 20, inclusive. The
kish was obtained from the hot-metal transfer station cleaning system at the
Weirton Steel Division of National Steel Corporation and the kish analysis
was 41.90% C, 22.86% Fe203, 15.87% CaO, 8.72% Si02, 1.83% MnO, 1.61% A1203,
1.50% MgO, 0.33% S, 0.01% P, and 5.73% L.O.I, (at 850°C).
Avarage hot metal temperature in the transfer ladle just prior to
removal of the ladle from the arc furnace tapping pit was 1412°C (2573°F) and
ranged from 1366°C (2490°F) to 1477°C (2690°F). Temperature loss in the
transfer ladle during holding was measured on five heats and the average was
ll°C/min. (19°F/min.). The average time between the last temperature
measurement and the hot metal charging was 1.6 min. Average calculated hot
metal temperature at the start of pouring, therefore, was about 1394°C
(2542°F).
Four types of scrap; clean plate, turnings, shredded automotive and
galvanized sheet steel, were used for the BOP scrap charge. The clean plate
was low-carbon steel waste cuttings from a welding shop. The turnings and
shredded automobile scrap were obtained from scrap dealers. The galvanized
scrap was sheared pieces of locally produced galvanized sheet steel.
BOP EQIIPMENT
The vessel had a rated capacity of 0.91 metric tons (1 net ton) and is
shown in Figures 11, 12 and 13. Inside diameter of the rammed chromic acid
bonded magnesia working lining was 813 mm (32 inches) and the inside height
was l.£3 m (72 inches). The height-to-diameter ratio of 2.25 was chosen to
simulate full size BOP geometry. Metal depth was 356 mm (14 inches). A
refractory lined air-cooled primary emission capture hood was located
directly above the vessel with a gap between the hood and vessel of 76 mm
(3 inches). The gap was designed to obtain 300% excess air during the steel-
making operation. A baghouse designed for a gas flow of 249 cu. m. per min.
(8800 ACFM) and a particulate loading of 2.86 gms per cu. m. (1.25 gr/ACF)
64
-------
was located approximately 46 m (150 ft.) from the vessel to obtain sufficient
gas cooling prior to cleaning. The baghouse was chosen instead of a wet
scrubber or precipitator because of maintenance considerations of a laboratory
installation.
Auxiliary equipment was added for the various experiments as required as
shown in Figures 14, 15 and 16. The slot-type hood was 1067 mm (42 inches)
wide and 279 mm (11 inches) deep and had a variable height slot. The hood
was connected to the main BOP hood system through a 230 mm (9-inch) diameter
duct. Valves were located in the ducts so that the main BOP hood could be
isolated from the auxiliary hood providing full fan capacity application to
the auxiliary hood.
The canopy hood was added to the slot type hood as shown in Figure 15.
It extended 610 mm (24 inches) out over the charging area and had a 152 mm
(6 inch) skirt. The height above the vessel, 1905 mm (75 inches), was chosen
to simulate positioning just above the crane in a full size shop.
The launder pouring system consisted of a special hood section fitted
with a 457 mm (18 inch) long, 190 mm (7.5 inch) wide launder with the inside
end located flush with the inside refractory lining of the hood; it was
assumed that a launder projecting inside the hood would not withstand the
temperatures and gas flows in a full size shop. It was necessary, therefore,
to tilt the vessel slightly to avoid pouring hot metal on the vessel top
ring. This would not be necessary on a full size vessel because the refrac-
tory thickness is much smaller with respect to the vessel diameter. The
launder was rammed with a 40 mm (1 1/2 inches) thick layer of a 90% alumina
refractory.
Vessel preheating was accomplished with a 152 mm (6 inch) diameter
natural gas burner adjusted to provide a heating rate of 6200 kg-cal per min.
(24,500 BTU/min.). Preheating was necessary to simulate operating conditions
of a full size vessel. Refractory temperature measured with an optical
pyrometer just prior to hot metal charging was 982°C (1800°F). The hot
metal and teeming ladles were similarly preheated with small gas-fired pre-
heat burners.
Oxygen, nitrogen and argon employed for the steelmaking operation and
the charging experiments were obtained from bottled gas located outside the
building adjacent to the furnace area.
BOP INSTRUMENTATION
The BOP was completely instrumented for steelmaking operations but the
only instrument pertinent to the charging emission study was the offgas
system flow rate gauge. An annular type flow sensor was located about 11 m
(35 feet) downstream from the BOP vessel mouth and a direct reading indicator
was mounted on the BOP control board. The meter was calibrated with pitot
tube measurements in the hood 2 meters (6 feet) above the vessel.
65
-------
PHOTOGRAPHY
A series of still black and white photographs was taken at increments of
5 seconds during each heat to provide a visual record of the emissions.
Color movies were also taken of most of the heats for the same purpose. The
movies were studied in detail and gas velocity measurements were made by
timing the rate of rise of puffs of smoke as was done for the full scale BOP
tests.
AIR POLLUTION TEST EQUIPMENT
Six different air pollution sampling trains were used in the sampling
of the fugitive emissions from the pilot BOP. Schematics of these systems
are found in Figures 17 through 22. These equipment trains were set up to
measure particulate concentrations; particle size distribution; obtain samples
for cheniical analysis of the gaseous emissions, the gases in the vessel and
the fugitive dust; and the transmittance of the fugitive emission plume.
The equipment used for the particulate concentration determinations was
a Glass Innovations Model GII-200 Source Sampler. It consisted of a heated
2.44 m (8 foot) probe fitted with a 6.4 mm (0.25 in.) stainless steel goose-
neck nozzle, a standard thimble holder and a 47 mm (1.85 inch) diameter
filter and holder. The thimble, an alundum type, and the filter, a Gelman
Type A, were at ambient temperature during the tests. Two 7.6 m (25 feet)
sections of umbilical cord were used to connect the probe to the bubbler
section. Four 300 ml bubblers were arranged so that the gas would first pass
through the two bubblers, each containing 150 ml of distilled water, and then
through two empty bubblers. The control module consisted of a vacuum pump,
slant manometer, dial thermometer, and dry gas meter.
Particle sizing was done with an Anderson 2000, Inc. "In-Stack Sampling
Head" fitted with a 6.4 mm (0.25 inch) diameter stainless steel gooseneck
nozzle. Suction was provided by a Cast vacuum pump and gas volumes were
measured with a Rockwell dry gas meter.
Tha samples for emission gas analysis were collected in two 250 cc glass
gas bottles. The gases were conveyed through a 3.18 mm (0.125 inch)
diameter stainless steel tube with suction provided by a Cast vacuum pump.
Th= gases from inside of the vessel were collected in four 250 cc glass
gas bottles arranged in parallel and suction was provided with a Millipore
vacuum pump.
Th= samples for the chemical analysis of the fugitive dust were
collected using a General Metals "Hi-Vol" sampler. The sampler has a collec-
tion area of 290 cm^ (45 in.2). Gelman Type A filters were used in the 60
cfm unit.
The transmittance of the emission plume was measured using a 5.9 milli-
watt CW laser, a Oriel Model D-50 Radiometer with a visible light detector
and a standard chart recorder. The distance between transmitter and
receiver was 15 m (50 feet).
66
-------
EXPERIMENTAL PROCEDURES FOR ENVIRONMENTAL TESTING
Since no sampling method for particulate concentration determination in
a fugitive emission has been universally accepted, the method used was a
compromise with both the EPA and ASTM recommended methods for stack sampling.
The problems associated with sampling this particular fugitive emission were
amplified because of the short length of each test run (average emission
time = 48 seconds) and the turbulence of the plume. In light of these
problems, and with full realization that, were possible, an isokinetic
sampling with preliminary velocity traverses would have given more accurate
data; the following sampling technique was utilized:
A tare weight was taken on a dry thimble and filter with a Mettler
four-place mechanical balance. The equipment train described in the previous
section was set up with the gooseneck nozzle located at the estimated point
of worst emission, 2.0 meters (6.7 feet) above the mouth of the vessel.
The system was leak checked and the pitot tube was checked for plugging.
The gas meter reading was then recorded. The sampling train was started up
when the first of the hot metal entered the vessel. During the charge the
temperature of the gas entering the meter as well as the temperature of the
emission plume was recorded every 15 seconds. The sampling train was stopped
when the last of the hot metal entered the vessel (even though the vessel
had not yet been turned up). The final gas meter reading was taken and the
thimble and filter were dried at 103°C and re-weighed.
An additional method for measuring the particle concentration was
provided in case problems with the main sampler arose. A dry gas meter was
installed behind the vacuum pump for the particle sizer so that the volume
sampled could be divided into the total weight of the material collected on
the particle sizing plates to give a value for the grain loading.
Particle size distribution was measured with the sampling train
mentioned in the "Air Pollution Test Equipment" section of this report.
Each stainless steel plate was dried at 103°C for 1 hour and weighed on a
four-place Mettler balance. The stainless steel nozzle was attached and the
sampler located at approximately the same sampling point as the particle
concentration system. A reading was taken from the dry gas meter before the
test began. The unit was started and stopped at exactly the same time as
the particle concentration sampling train. At the completion of the test
the plates were dried and reweighed and a final meter reading was taken.
For chemical analysis of the emission gases, the two gas bottles were
connected in series in the sampling train. The vacuum pump was turned on
simultaneously with the other test equipment. The gas bottles were closed
towards the end of the charge. Gases were then analyzed for N2, 02, CO,
C02, CH^, NO and N02 with a gas chromatograph.
For chemical analysis of the vessel gases, four gas bottles were
connected in parallel to allow for a short interval between samples. One
67
-------
vessel gas sample was taken just before the charge and the other three were
taken every 15 seconds during the charge. The samples were analyzed in the
same manner as the emission gas samples.
A hi-vol sampler was positioned 0.61 m (2 feet) above the other
samplir.g trains to obtain samples of fugitive dust for analysis. The sampler
was rur. during the entire length of the charge. After the tests, the filter
was removed and the collected dust was removed from the filter. The dust.
was then analyzed on an emission spectrograph, which listed each constiutuent
of the dust as either a major (>1%), minor (>0.1% but <1%) or a trace (<0.1%).
The samples were then quantitatively analyzed for each element listed as a
major cr minor. This analysis was done using atomic absorption and wet
methods.
Transmittance of the emission plume was measured with the laser system
outlined in the previous section. The Radiometer was located at a height of
2.64 meters (8.67 feet) above the vessel mouth. The chart recorder was
placed in a location 4.6 meters (15 feet) away from the vessel. The laser
beam w£.s turned on before each heat and the Radiometer and recorder were
calibrated using standard opaque filters. During the heat the recorder pro-
duced i. plot of opacity vs. time.
The results of each of these tests are found in Tables 14 through 18
and are discussed in the sections which follow.
RESULTS AND DISCUSSION
There were, broadly considered, three types of variables in the study:
1. kish additions, 2. scrap type and 3. emission control systems. These
variables were changed independently and, in some cases, concurrently during
the course of experiments as experience was gained and as test results were
evaluated. The results and discussion must therefore take overlapping of
these variables into consideration. Each variable will be treated separately
with notations of interrelated effects where applicable.
Kish Additions
The first heat made had no emission control system in operation. The
participate captured on the hi-vol sampler exhibited a fine texture and a
light gray appearance which was completely different from the black kish-
containing particulate obtained during the trials at the Weirton Steel
Division (section 8). It was tentatively concluded that the amount of kish
developed by carbon rejection during cooling of the hot metal was insignifi-
cantly small. For the second heat 1.1 kg (2.4 Ib.) addition of kish which
was obtained from the Weirton Steel Division kish collection system at the
BOP shcp was added to the transfer ladle immediately after filling the trans-
fer ladle from the electric arc furnace. The 1.1 kg addition was calculated
from the kish density and the ladle geometry to provide a 3 mm (1/8-inch)
thick layer of kish on the hot metal. The particulate samples exhibited a
few flekes of graphite but still was not representative of the emission at
Weirton Steel Division. Carbon content of the sample was 1.2% which was
significantly less than the overall average of 41.6% C observed during the
68
-------
the Weirton tests.
The kish addition was increased to 3.4 kg (7.5 Ibs.) for test No. 3 and
to 6.8 kg (15 Ibs.) for test No. 4. Test No. 3 particulate exhibited more
kish than tests 1 and 2 and test No. 4 had an appearance quite similar to the
Weirton Steel BOP emissions. Calculated layer thickness on the ladle for the
6.8 kg addition was 20 mm (0.78 inch). The 6.8 kg addition was held constant
for the remaining heats.
The technique of adding kish to the ladle is a valid method for obtain-
ing kish in the emissions. It was noticed during the Weirton Steel Division
tests that a substantial amount of kish was on the hot metal in the ladle
prior to charging of the BOP. This kish evidently was produced from the hot
metal by carbon rejection as the hot metal cooled in the torpedo car used to
transport the hot metal from the blast furnace to the BOP shop and during
pouring of the hot metal from the torpedo car to the transfer ladle.
The kish additions introduced an unplanned variable into the program.
Not all of the kish added to the transfer ladle was transferred into the BOP
during charging because, on occasion, a small weir developed in the transfer
ladle from solidifying hot metal which held back some of the kish. It was
not possible to measure the amount retained in the transfer ladle because
much of the retained kish was distributed over the transfer ladle walls and
some became airborne during ladle handling after charging.
Another related variable was the time between the kish addition and the
BOP charging during which some of the kish burned. It is not known if this
variable was significant.
It was concluded that part of the kish in the charging emissions is
carried over from previous operations and, therefore, a minimization of the
carryover would reduce kish emissions during the charging operations. It is
not known if the lack of kish generation during charging was typical for all
BOP shops or particular to the model because of differences of modeling
factors such as scrap surface area to hot-metal weight ratio and scrap volume
to hot-metal weight ratio.
Effects of Scrap Type
The scrap mix for the first eight heats was 85% clean scrap, 3.8% oily
turnings, 5.6% shredded automotive scrap and 5.6% galvanized sheet steel.
The emission appearance was light gray and was not typical of full size
operations. Chemical analysis of the particulate emissions showed for these
heats zinc oxide contents much greater than that obtained during the full
scale tests; average ZnO for the model tests was 61.0% whereas the full size
vessel tests exhibited an overall average of 6.4%. The scrap mix was,
therefore, changed by eliminating the galvanized sheet steel and replacing
it with shredded automotive scrap resulting in a scrap mix of 85% clean
scrap, 3.8% oily turnings and 11.2% shredded automotive scrap. Zinc oxide
content for the heats with the modified scrap charge averaged 7.9%. The
emission appearance and analysis were more typical of the full size tests.
69
-------
This scrap mix was employed for the remaining heats excepting No. 18
which w.is made with galvanized scrap to obtain improved visibility. This
will be described in a later section.
It was concluded that galvanized steel scrap did have an influence on
the type of emissions. This influence, however, did not materially influence
the evaluation of the various emission capture systems.
Base Coidition^ Heats
Four heats (Nos. 1, 2, 5 and 9) were made without any charging emission
control systems in operation. The main vessel hood was also turned off. The
purpose was to develop base condition data which could be employed for com-
parisons of the various control systems investigated. Variables involved
were the amount of scrap charged, the kish addition and the amount of gal-
vanized scrap in the charge. Heat Number 1 had a scrap charge of 15.9%, no
kish and galvanized scrap. The scrap charge was increased to 21.1% for heat
Number 2 and a 1.1 kg kish addition was made to the transfer ladle as dis-
cussed previously. Heat No. 5 had the "standard" 26.4% scrap charge, a 6.8
kg kish addition and galvanized scrap. Heat Number 9 was the same as heat 5
except that galvanized scrap was not included in the charge.
Heats 1 and 2 exhibited a dense light gray emission and a flame extending
about 1 meter above the vessel mouth, Figures 23 and 24. Heat No. 5 had less
flame and a darker emission, Figure 25. Heat 9 had a flame similar to heats
1 and 2 and a darker emission, Figure 26. Average transmittance values,
Table 14, were 0.03, .32 and 0.13 for heats 2, 5 and 9, respectively, and the
overall average was 0.16. (The test results for heat 1 were not properly
calibrated.) Dust loadings, Table 15, were 5.79, 6.64, 2.38 and 6.12 gms/m^,
respectively, and the overall average was 5.23. The transmittance and dust
loading results confirmed the visual observations.
Mean particulate diameter averaged 1.8 microns and ranged from 1.5 to
2.4 microns.
It was concluded from these heats that the model did have emissions
similar to a full size BOP and, therefore, that the model could be employed
for emission capture system evaluations.
Slot Type Hoods
Slot type hoods were tested to determine the effects of slot opening
size (See Figure 14). Slot opening heights investigated were 25 mm (1"), 51
mm (2") and 102 mm (4") for heats 6, 3 and 4, respectively. Effective slot
width vas held constant at 1029 mm (40.5 inches). Exhaust gas volume
measure.d with a pitot tube in the duct immediately above the hood was 92.5
m-Vmin. (3270 CFM) and face velocities at the slot opening were calculated
to be 887, 1770 and 3550 m/min. (2910, 5820 and 11700 fpm) for the 25, 51 and
102 mm slots, respectively.
Very little capture by the slot hoods was observed during the three
heats c.s shown in Figures 27, 28 and 29. Dust loadings averaged 4.42
70
-------
and transmittance averaged 0.33. The amount of emissions from Heat Number 3
was significantly lower than for the no emission control heats. Efforts to
relate this emission variation to scrap charge, practice etc. were unsuccess-
ful.
Exhaust gas velocity measured with a pitot tube at various distances
from the hood opening and theoretical velocities calculated from the Dalla
Valle equation describing air approaching a plain circular opening along the
duct axis are shown in Figure 43. The velocity drops rapidly as the distance
from the hood opening is increased and at a distance of 150 mm (5.9 inches)
the velocities are essentially independent of the slot face velocity. This
means that the hood slot size has essentially no effect on the air velocity
at distances from the hood of greater than 150 mm (5.9 inches).
A rule of thumb is that the required capture velocity for effective
capture of a turbulent air stream is 600 m/min. (2000 fpm). According to the
calculated velocity profile this criterion is met at locations away from the
hood of only 112 mm (4.4 inches), 99 mm (3.9 inches) and 69 mm (2.7 inches)
for the 102, 51 and 25 mm slots, respectively. Emissions farther away from
the hood will not be effectively captured.
The only way to increase the slot hood effectiveness is to increase the
fan capacity. Calculated fan hood capacity for the pilot unit that would be
required to obtain a critical capture velocity of 600 m/min. at a distance of
.46 m (1.5 feet) from the hood, the approximate emission plume diameter is
2260 nr/min. (80,000 CFM) ; this is 24 times the available capacity. The
tests at the Weirton Steel Division showed that a calculated hood capacity
of 130,000 m3/min. (4,500,000 CFM), 11 times the available capacity, would be
required. It was concluded therefore that slot-type hoods would not be
practical.
Inert Gas Purging
Inert gas purging of the vessel prior to and during hot metal charging
was investigated with six heats. Argon was employed for heats 7 and 10 and
nitrogen was employed for heats 8, 11, 14 and 19. The operating procedure
was to tilt the vessel to the normal charging position, charge the scrap,
initiate the purge and start hot metal pouring 4 to 5 minutes after the
start of purging. Purging was continued during hot metal charging. A movable
steel pipe with an inside diameter of 15 mm (.59") was used to convey the
test gas to the vessel and was inserted approximately halfway into the vessel.
Purging rate for the first two heats (7 and 8) was 0.54 m3/min. (19 CFM).
This rate was chosen to obtain sufficient gas for completely filling the
vessel three times during the 4 minute purging time. The gas flow rate was
tripled to 1.7 m^/min. (60 CFM) for the remainder of the series.
Argon purging at 0.54 m^/min. had essentially no effect on emissions as
shown in Figure 30 and as measured with the laser system, Figure 45. Increas-
ing the purging rate to 1.7 nrVmin. resulted in a slight decrease in emissions,
Figure 31.
71
-------
There was a significant difference in the particle size distribution,
Figure ^8. The particulate emissions from the purged heats exhibited a larger
mean diameter particle size and had a smaller proportion of fine particles.
It was not possible to perform a detailed chemical analysis because of the
small anount of sample captured but it appears that the purging did suppress
formation of fine oxide particles but had little or no effect on suppressing
generation of larger particles.
Nil:rogen purging at 0.54 mVmin. had no apparent effect on charging
emissions, Figure 32. Results of the three heats at the higher nitrogen flow
rate were quite variable, Figures 33, 34 and 35. The second heat in the
nitrogen purge series exhibited control slightly better than the second argon
heat, "t was decided to duplicate this heat to determine if this observation
was val:.d. This heat, No. 14, showed excellent emission control. There was
essentially no flame from the vessel mouth and emissions visually observed
and measured with the laser system were successfully suppressed. Another
heat waii therefore made to try to duplicate this performance. This heat,
Heat No. 19, exhibited emission control similar to the second nitrogen heat -
somewhat better than the uncontrolled heats but not good enough to be con-
sidered as an effective system.
Special gas sampling tests were conducted during the last four purging
heats and during the closure plate heats (described later) which provide some
insight into the reasons for the observed variability. A gas sampling tube
was inserted about 250 mm (10 inches) into the vessel and gas samples were
obtained during purging and pouring for chemical analyses. Results are shown
in Table 16. Of particular interest is the oxygen content in the vessel just
prior to pouring which should give an indication of the purging effectiveness.
The lowest oxygen, 5.0%, was observed for the best test, the third nitrogen
purge hf.at. A good correlation however between oxygen content in the vessel
and emijisions was not observed. There was a large variation in the oxygen
content ranging from 5.0% for heat No. 14 to 15.3% for heat No. 11.
It was concluded that gas purging with a lance type device exhibits a
large variability in effectiveness. Eddy current generation in the vessel
from the relatively high purging gas velocities results in air inspiration
into the vessel. Convection currents generated as the purging gas becomes
heated also results in air inspiration.
Another indication of the air inspiration effect was noted during hot
metal charging of the closure plate heats. It was expected that the charging
reactions would result in a vessel atmosphere containing principally CO and
C02- The highest measured CO and C02 contents, however, were only 6.8% and
13.0%, respectively. Air inspiration may have been partly responsible for
this observation.
Other gas delivery systems such as porous plugs and gas diffusers were
considered but it was concluded that these systems would not be reliable be-
cause oi: the high operating temperatures in the hoods and vessels.
It was concluded that inert gas purging would not be a practical emission
control system in full size BOP shops because of the large variability in
72
-------
effectiveness.
Closure Plate
Two heats were made to evaluate the patented closure plate system. For
the first heat a sheet metal plate was placed about 10 mm (3/8 inch) below the
main hood and covered 64% of the main hood opening. Calculated gas velocity,
assuming a uniform velocity distribution, was 750 m/min. (2460 fpm). Tilting
the vessel disturbed the uniform velocity distribution and the velocity in the
area between the hood and the vessel opening measured with a pitot tube was
760 m/min. (2500 fpm). Emission capture with this system as indicated
visually and as measured was excellent, Figure 36. Measurements of the gas
velocity leaving the vessel during this heat with a hand held pitot tube
indicated a fume velocity of about 230 m/min. (750 fpm), substantially lower
than the system capture velocity.
A second heat was made with the plate removed and the same angle of
vessel tilting. Measured velocity in the hood vessel opening gap was 245
m/min. (800 fpm) which was slightly greater than the vessel emission velocity.
Capture with this configuration was very good but not quite as effective as
with the plate installed; several puffs escaped the hood during the second
test.
It should be noted that the pilot unit operations were quite different
from full size vessels in that much lower emission velocities were obtained
from the pilot vessel (230 m/min. for the pilot vessel and 900 m/min. at the
Weirton vessel) and that the gas velocity in the main hood provided by the
baghouse equipped hood system was much higher than that obtained on full size
vessels. The distance from the source of the emissions to the hood was also
much smaller than that for a full size system (2 m on the model and 9 m at
Weirton).
It was concluded that the closure plate system will be effective if the
capture velocity at the vessel mouth is greater than the emission velocity
and if the hood system has sufficient gas handling capacity. It is not
possible to quantify the velocity and gas handling capacity required from the
limited data available.
Launder Pour
Two heats were made with a launder attached to the main hood located such
that hot metal could be poured through the launder into the vessel which was
essentially upright, Figure 16. Full hood gas flow of 292 m3/min. (10,300
CFM) was employed for the first heat (Heat No. 15) and about half that, 139
m3/min (4900 CFM), was employed for the second heat (Heat No. 16). Emission
capture was excellent for both heats, Figures 38 and 39. Dust loading for
the two heats averaged 1.37 gms/m3 (0.60 gr/ft3), about one quarter of that
observed with the no emission control heats.
It was concluded that the launder pour system would be satisfactory pro-
vided that a method of installing a practical launder is developed.
73
-------
Canopy Hood
Two heats with a canopy hood located above the vessel mouth when the
vessel was in the charging position were conducted. For the first heat, Heat
No. 17, volumetric flow rate was 93 m^/min. (3270 CFM) and measured hood
opening velocity was 122 m/min. (400 fpm). For the second heat a volumetric
flow of 46 m3/min. (1640 CFM) and velocity of 61 m/min. (260 fpm) was employ-
ed. Capture was very good for the first heat, Figure 40, and marginal for
the second, Figure 41. Essentially all the emissions directly under the hood
were effectively captured; emissions not directly under the hood were not
captured.
It was concluded that a canopy hood system would be satisfactory if it is
large enough to encompass the entire emission plume and if the system has
sufficient exhaust capacity.
Slow Pouring
The last heat in the series was a slow pour heat. An unplanned for
variable was introduced which was quite interesting. The ladle operator was
instructed to try for a 2 minute pour but this was difficult because of a lack
of operating experience. The operator started at a slow rate and maintained
that ra(:e until 100 seconds into the pour. At that time he realized that he
would overrun the specified 2 minutes and he therefore increased the pouring
rate for the last 20 seconds. There were essentially no emissions during the
first 100 seconds, but the emissions increased markedly when the rate was
increased after 100 seconds as shown in the photographs, Figure 42 and the
transmit:tance trace, Figure 47.
Dust concentration for this heat was the lowest of all the heats, 0.74
gms/m (0.32 gr/ft ). It was not possible to determine if the total emission
was reduced or if it was the same amount of emission generated over a longer
time period.
It was not possible to evaluate effectiveness of slow pouring with
various types of scrap. Emissions from heats with galvanized steel scrap, for
example, are considerably different from emissions investigated with this
single experiment and they might not be effectively controlled by slow pouring.
It is not known what pouring times would be required for full size BOP
shops but it appears that there is a critical pouring rate below which
emissioris are substantially reduced. It was concluded, therefore, that slow
pouring can reduce emissions but serious problems related to reduced shop
productivity will result.
Conclusions
It was concluded from the pilot BOP tests that:
1. At least part of the kish observed in the particulate emissions is kish
carried over from previous operations and that, therefore, a means employed
to minimize kish carryover would reduce the amount of particulate emission.
74
-------
It is not known if this observation is valid for full size vessels.
2. Galvanized steel scrap had an influence of the type of emissions observed.
3. It was found that slot type hoods are not satisfactory because the
effective capture area, the area adjacent to the hood in which the hood will
divert gas flow, is relatively small.
4. Effects of inert gas purging of the vessel prior to and during charging
were quite variable and it was concluded that gas purging would not be
practical.
5. Tests of the Gaw closure plate system were successful at capturing
emissions and it was concluded that the system will be effective if the cap-
ture velocity at the vessel mouth is sufficient and if the hood system has
enough volumetric capacity to handle the emissions.
6. Pouring through the main hood with a launder was very successful.
7. It was found that a canopy type hood would be satisfactory if it is large
enough to encompass the entire emission plume and if the gas handling system
has a large enough capacity.
8. Slow pouring was found to reduce the rate of emissions, but further tests
to establish effects of scrap type and the effectiveness on full size vessels
are suggested.
75
-------
TABLE 12. SUMMARY OF PILOT VESSEL TEST HEATS
Heat No. 1:
Heat No. 2:
Heat No. 3:
Emission control systems were turned off for establishing base
condition data.
Heat No. 1 was repeated except for a 1.1 kg kish addition to the
transfer ladle and an increase in the total scrap charge from
15.9 to 21.1%.
The slot hood with a 51 mm slot height was operated. The kish
addition was increased to 3.4 kg and the scrap charge was further
increased to 23.6%.
Heat No. 4:
Heat No. 5:
Heat No, 6:
Heat No,
Heat No,
7:
8:
Heat No. 9:
Heat No, 10:
Heat No. 11:
Heat No,
Heat No,
12:
13:
Heat No, 14;
The slot hood was again operated but the slot height was
increased to 102 mm. The kish addition was increased to 6.8 kg;
this addition was maintained for the balance of the heats.
Effects of the kish addition on base line conditions were
evaluated by conducting a third heat with emission control
systems not operating. The scrap charge was increased to 26.4%
and this was held constant for the balance of the heats.
This was the third slot hood test and the narrowest slot, 25 mm,
was evaluated.
Inert gas purging was tried with argon injection.
The second inert gas purging trial was made with nitrogen gas
instead of argon.
Galvanized scrap was eliminated from the scrap charge and was
replaced with automotive scrap. Emission control systems were
not operated so that the effects of scrap type could be
investigated.
A second inert gas purging heat with argon injection was made
and the gas input rate was tripled.
This heat was similar to No. 10 except that nitrogen was the
inert gas injected.
The closure plate emission control system was evaluated.
A second closure plate system heat was made. The plate was
removed to obtain data on effects of gas velocity.
The previous inert gas purging trials with nitrogen were incon-
clusive and this heat was a repeat of heat no. 11.
Heat No, 15: The launder pour concept was tried.
76
-------
TABLE 12. (CONTINUED)
Heat No. 16: The launder pour concept was repeated with the gas flow in the
hood reduced 50%.
Heat No. 17: The canopy hood was evaluated.
Heat No. 18: The canopy hood was re-evaluated with the hood flow reduced
50%. Galvanized scrap was included in the charge to increase
the emission visibility.
Heat No. 19: The use of nitrogen to purge the vessel was again tried to ob-
tain further data concerning previous inconsistencies in
effectiveness.
Heat No. 20: Effects of slow hot metal pouring were evaluated.
77
-------
00
TABLE 13.
Scrap
No.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
HI _»-~
• Ibs.
225
319
370
370
425
425
425
425
425
425
425
425
425
425
425
425
425
425
425
425
T. , -^_ -I « «.,-,
Ibs.
10
14
16
16
19
19
19
19
19
19
19
19
19
19
19
19
19
19
19
19
*..,-„
Ibs.
15
21
24.5
24.5
28
28
28
28
56
56
56
56
56
56
56
56
56
28
56
56
PILOT
r--,!^
Ibs.
15
21
24.5
24.5
28
28
28
28
0
0
0
0
0
0
0
0
0
28
0
0
VESSEL
T~<-ol
Ibs.
265
375
435
435
500
500
500
500
500
500
500
500
500
500
500
500
500
500
500
500
TESTS
%
15.9
21.1
23.6
23.9
26.4
26.4
26.3
26.4
26.4
26.4
26.4
26.3
26.3
26.3
26.3
26.4
26.4
26.4
26.3
26.4
- CHARGING DETAILS
Hot
Ibs.
1406
1400
1405
1395
1392
1392
1400
1392
1389
1389
1395
1400
1399
1400
1401
1393
1392
1397
1402
1395
Ten1." .
°C
1468
1477
1399
1460
1421
1416
1416
1410
1388
1388
1399
1416
1404
1421
1404
1410
1366
1393
1388
1391
C
5.01
4.73
4.47
4.26
4.21
4.27
4.21
4.23
4.04
3.26
4.10
3.97
4.23
4.12
4.20
4.24
4.28
4.21
4.22
4.25
Metal
r/>m«
Si
1.20
1.83
1.17
1.53
1.58
1.39
1.43
1.47
1.36
1.40
1.33
1.36
1.41
1.31
1.41
1.38
1.43
1.53
1.33
1.37
/>o-! <--! ~
Mn
.84
.81
.78
.96
.97
.97
.98
.97
1.00
1.05
1.04
1.00
1.02
1.05
1.03
1.02
1.05
1.02
1.04
.98
r. 7*
s
.017
.009
.008
.009
.014
.009
.010
.013
.015
.006
.009
.008
.009
.007
.009
.008
.007
.010
.006
.007
P
.10
.09
.09
.15
= 15
.13
.12
.13
.12
.14
.11
.12
.11
.12
.09
.09
.12
.12
.11
.11
*Averages - 0.011% Cu, 0.21% Cr, 0.019% Ni, 0.013% Mo, 0.011% Al, 0.010% V and 0.039% Ti.
-------
TABLE 14. PILOT VESSEL TESTS - TRANSMITTANCE RESULTS
Emission Heat Transmittance, %
Control System
None
it
ii
ii
ii
Slot Hood- 25 mm
" 51 mm
" 102 mm
M
Argon Purge
M
II
Nitrogen Purge
ii
M
ii
n
Closure Plate
n
"
Launder Pour
M
M
Canopy Hood
"
M
No.
1
2
5
9
avg.
6
3
4
avg.
7
10
avg.
8
11
14
19
avg.
12
13
avg.
15
16
avg.
17
18
avg.
Mean
0.03
0.32
0.13
0.16
0.21
0.71
0.06
0.33
0.18
0.59
0.38
0.02
0.72
0.94
0.75
0.61
0.89
0.91
0.90
0.87
0.91
0.89
0.93
0.86
0.90
Minimum*
0
0.10
0.01
0.04
0
0.07
0
0.02
0
0.11
0.06
0
0.29
0.84
0.16
0.43
0.76
0.77
0.76
0.42
0.66
0.61
0.58
0.29
0.49
Slow Pour 20 .89 0.59
*Includes peaks not shown in figures.
79
-------
TABLE 15. PILOT VESSEL TESTS - DUST LOADING AND PARTICULATE SIZE OF EMISSIONS
Particulate Size
Emission
Control System
None
IT.
II
II
Slot Hood- 25 mm 6
" 51 mm 3
102 mm 4
avg.
00
Argon Purge
Nitrogen Purge
Closure Plate
Launder Pour
Canopy Hood
Slow Pour
7
10
avg.
8
11
14
19
avg.
12
13
avg.
15
16
avg.
17
18
avg.
20
gms/m-5 gr/ftj
5.79
6.64
2.38
6.12
5.23
5.42
1.50
6.33
4.42
8.24
5.61
6.92
13.4
3.11
1.38
3.04
5.23
0.75
1.15
0.95
1.61
1.13
1.37
1.20
0.77
0.88
0.74
2.55
2.89
1.03
2.69
2.29
2.38
0.66
2.76
1.93
3.61
2.45
3.03
5.82
1.36
0.60
1.33
2.28
0.32
0.51
0.42
0.71
0.50
0.60
0.52
0.34
0.43
0.32
Cumulative
12.5
95.7
90.0
91.6
87.7
91.2
90.9
98.2
92.0
93.7
92.8
84.2
88.5
94.1
86.2
70.4
84.1
83.7
57.2
70.1
63.6
74.5
67.4
71.0
70.9
59.8
63.4
79.1
8.0
90.0
82.6
82.8
80.3
83.9
84.6
93.2
85.6
87.8
73.1
64.9
69.0
89.7
76.2
57.6
70.7
73.6
47.3
58.6
53.0
55.5
55.8
55.6
57.6
51.0
54.3
68.5
Wt. %
5.3
81.7
77.9
75.4
73.8
77.2
78.4
89.5
78.9
82.3
53.1
46.6
49.8
84.3
61.1
44.8
57.1
61.8
39.3
47.8
43.6
44.5
45.6
45.0
44.9
43.1
44.0
59.4
Less Than Stated Micron Size
3.4
66.8
71.4
70.2
67.4
70.0
70.5
80.2
69.0
73.2
43.1
28.3
35.7
75.8
43.0
35.5
51.0
51.3
33.9
35.7
34.8
35.7
37.4
36.6
33.6
38.2
35.9
53.9
2.6
47.4
59.6
59.9
56.7
55.9
57.9
62.3
57.1
59.1
32.5
19.4
26.0
63.7
25.7
24.4
39.1
38.2
29.5
25.5
27.5
25.1
30.6
27.8
22.8
32.4
27.6
44.9
1.4
28.3
43.2
46.9
43.9
40.6
42.4
33.9
43.1
39.8
23.6
14.4
19.0
47.8
17.1
15.7
29.7
27.6
23.2
14.6
18.9
16.0
23.2
19.6
13.9
22.6
18.2
36.2
0.
8.
21.
17.
20.
11.
13.
4.
20.
12.
9.
7.
8.
23.
9.
7.
13.
13.
14.
7.
10.
8.
9.
9.
5.
9.
7.
19.
8
6
4
5
2
9
2
2
0
5
2
3
2
8
3
6
6
6
3
0
6
4
5
0
7
8
8
3
0.
2.
7.
6.
9.
6.
4.
1.
6.
4.
3.
3.
3.
6.
5.
5.
6.
5.
9.
4.
7.
5.
6.
5.
3.
4.
4.
9.
5
7
1
8
1
4
5
2
5
1
1
7
4
4
4
2
6
9
8
5
2
3
1
7
8
9
4
8
Mo a~r»
Diameter,
Microns
2
1
1
1
1
1
1
1
1
4
5
4
1
3
6
3
3
10
6
8
6
6
6
6
7
6
2
.4
.7
.6
.5
.8
.9
.7
.7
.8
.1
.6
.8
.5
.8
.0
.5
.7
.0
.0
.0
.4
.0
.2
.0
.0
.5
.9
-------
TABLE 16. PILOT VESSEL TESTS - GAS COMPOSITION IN THE BOP VESSEL
Emission Heat
Control System No.
Composition, %
Closure Plate
Closure Plate
Argon Purge
oo
it
ii
Nitrogen Purge
12
13
10
11
it
Nitrogen Purge 14
Nitrogen Purge 19
it
it
Time of Sample
Before Pour
15 sec. into Pour
30 sec. into Pour
45 sec. into Pour
Before Pour
15 sec. into Pour
30 sec. into Pour
45 sec. into Pour
Before Pour During Purge
15 sec. into Pour
30 sec. into Pour
45 sec. into Pour
Before Pour During Purge
30 sec. into Pour
45 sec. into Pour
Start of Purge
Middle of Purge
End of Purge
Start of Pour
Start of Purge
End of Purge
Start of Pour
02
22.0
18.7
16.8
22.7
21.1
9.7
10.6
11.0
11.8
29.0
20.8
21.6
15.3
6.3
9.0
18.5
13.5
5.0
5.8
6.9
6.3
10.4
CO
0
0.1
0.1
0.1
0
6.8
4.4
0
0.1
7.1
2.8
1.8
0
3.6
0.3
0.4
0.3
6.8
5.3
0
1.7
1.6
CO?
0.1
9.8
6.4
5.6
0.4
13.0
10.8
9.2
0.6
4.0
1.6
1.0
1.1
8.5
13.5
0.5
1.3
7.7
9.1
0.5
9.8
6.7
_N_2
78.4
80.8
69.8
78.8
76.1
72.4
69.9
67.7
61.0
56.0
61.0
75.0
70.9
76.0
88.0
73.6
72.7
63.7
69.5
65.4
73.7
74.5
CH_4
0.09
0.07
0.08
0.07
0.10
1.39
1.65
0.15
0.08
1.50
1.20
0.45
0.99
1.21
0.22
0.05
0.07
1.25
1.02
0.07
0.06
0.06
-------
TABLE 17. PILOT VESSEL TESTS-CHEMICAL COMPOSITION OF GASEOUS EMISSIONS
Composition, %
Emission
Control System
None
M
II
Slot Hood- 25 mm
" 51 mm
11 102 mm
ti
Argon Purge
M
II
Nitrogen Purge
M
M
ii
M
Closure Plate
ii
n
Launder Pour
M
Heat
No.
5
9
avg.
6
3
4
avg.
7
10
avg.
8
11
14
19
avg.
12
13
avg.
15
16
N9
80.
42.
61.
75.
68.
71.
71.
79.
76.
77.
82.
64.
74.
73.
73.
73.
76.
74.
80.
79.
0
5*
2
0
0
0
3
0
0
5
0
6
8
7
8
7
1
9
0
0
°?
18.
12.
25.
16.
15.
19.
17.
20.
21.
21.
18.
15.
20.
18.
18.
18.
21.
20.
18.
18.
8
7
3
6
2
8
2
6
6
1
4
5
5
5
2
7
6
2
4
4
CO
0
-
_
-
-
-
_
0.1
—
-
0
0.2
0
0
0
0
0
_
-
C02
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
.1
.7
.6
.1
.4
.2
.1
.2
.4
.7
.4
.5
.1
.5
.3
.9
.6
CH4
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
.01
.02
.05
.03
.02
.01
.02
—
.17
—
.06
.00
.06
.09
.08
.09
.13
.11
.07
.05
Total
99.8
55.2
92.8
83.3
90.8
89.0
99.7
97.9
98.8
90.4
80.7
96.3
92.7
94.5
92.7
98.3
95.5
99.4
98.1
avg. 79.5 18.4 -
0.8 0.06 98.8
Canopy Hood
17
18
avg.
74.9
72.3
73.6
18.7 -
22.0 -
20.4 -
2.7
0.1
1.4
0.09
0.08
0.08
96.4
94.5
95.4
Slow Pour
20 78.8 22.4 0
1.5 0.12 102.8
*Analytical difficulties encountered.
82
-------
TABLE 18. PILOT VESSEL TESTS-CHEMICAL COMPOSITION OF PARTICIPATE EMISSIONS
Emission
Control System
None
Slot Hood- 25 mm
51 mm
102 mm
II
II
Argon Purge
Nitrogen Purge
Closure Plate
Launder Pour
Canopy Hood
Slow Pour
Heat
No.
1
2
5
9
avg.
6
3
4
avg.
7
10
avg.
8
11
14
19
avg.
12
13
avg.
15
16
avg.
17
18
avg.
Chemical
Fe
2.4
1.8
13.7
16.9
8.7
10.3
9.6
5.4
8.4
12.6
18.0
15.3
2.6
19.3
15.0
15.3
13.0
A
A
-
24.2
A
—
A
A
-
CaO
1.2
AA
1.3
0.9
1.1
1.0
0.8
0.7
0.8
2.3
0.6
1.4
AA
0.3
0.5
0.7
0.5
A
A
-
0.4
A
-
A
A
-
MgO
0.22
0.06
0.17
0.95
0.35
0.15
0.22
0.12
0.16
0.20
0.28
0.24
0.04
0.22
0.53
0.32
0.36
A
A
-
0.36
A
—
A
A
-
A1203
0.17
AA
0.18
0.21
0.36
0.18
0.21
0.06
0.15
0.23
0.34
0.28
AA
0.27
0.49
0.18
0.31
A
A
-
0.21
A
-
A
A
-
Composition, %
PbO
0.5
0.5
0.4
1.9
0.8
0.4
0.3
0.4
0.4
0.5
0.7
0.6
0.6
0.6
0.1
0.9
0.5
A
A
-
0.0
A
-
A
A
-
ZnO
79.3
88.7
22.6
31.0
55.4
37.8
64.1
76.2
59.4
35.6
1.9
18.8
84.0
0.5
0.3
12.5
4.4
A
A
-
0.2
A
-
A
A
-
MnO
0.11
AA
0.21
0.31
0.21
0.89
0.13
0.06
0.39
0.20
0.43
0.32
AA
0.25
0.18
0.23
.22
A
A
-
0.18
A
-
A
A
-
c
A
1.2
A
29.6
15.4
33.8
8.8
A
21.3
A
70.9
-
4.2
75.9
A
65.3
70.6
A
A
-
61.2
A
-
A
A
-
20 20.7 0.6 0.31 0.31 0.9 8.7 0.43
*Insufficient sample; **Not measured.
83
-------
oo
610mm
1830mm
6IOmm Diameter - Stainless Steel Duct
Refractory Lined, Air Cooled Hood
457mm Diameter Opening
813mm Diameter - Magnesia Lining
60mm Diameter - Oxygen Lance
(6.4mm Diameter Tip)
Metal Level
356mm
Figure 11. Experimental BOP Vessel and Hood
-------
Fig. 12. Experimental BOP Vessel.
-------
Fig. 13. Experimental BOP Installation
86
-------
oo
I (
279
nun
To
Baghouse
660mm
229ram Dia. Duct
965mm
L
1067mm
1092mm //
I
Variable Height Slot
(25 to 102 mm range)
Figure 14. Slot Hood Details.
-------
oo
00
610mm
i-
1905mm
//T\
Figure 15. Canopy Hood Details.
-------
I
00
267mm
n
Figure 16. Launder Pour Details
-------
1.
2.
3.
4.
XX
Figure 17. Grain Loading Sampling Train
1/4" Gooseneck Nozzle
Thimble Holder
47 mm Filter
S.S. Probe
5. Filter Box (No Filter)
6. Umbilical Cord
7. Bubblers
8. Control Module
0
12 3
Figure 18. Particle Size Sampling Train
1. 1/4" Gooseneck Nozzle
2. Particle Sizer
3. Vacuum Pump
4. Dry Gas Meter with Thermometer
-------
Figure 19. Gaseous Emission Sampling Train
1. 1/8" Steel Probe
2. Gas Bottles
3. Vacuum Pump
Figure 20. Vessel Gas Sampling Train
1. 1/8" Steel Probe
2. Gas Bottle Manifold
3. Vacuum Pump
-------
High Volume Sampler
Figure 21. Particulate Sample Collection Train
-D.
Figure 22. Transmittance Measurement Train
1. Laser Source
2. Detector
3. Recorder
-------
.
Fig. 23. No Emission Control, Heat No. 1,
-------
I
i
i
Fig. 24. No Emission Control, Heat No. 2.
-------
Fig. 25. No Emission Control, Heat No. 5.
-------
[
1
Fig. 26. No Emission Control, Heat No. 9.
-------
I
Fig. 27. 25mm Slot Hood, Heat No. 6.
-------
Fig. 28. 51mm Slot Hood, Heat No. 3.
-------
Fig. 29. 102mm Slot Hood, Heat No. 4.
-------
)
-I
Fig. 30. Argon Purge, Heat No. 7.
-------
Fig. 31. Argon Purge, Heat No. 10.
-------
•
Fig. 32. Nitrogen Purge, Heat No. 8.
-------
Fig. 33. Nitrogen Purge, Heat No. 11.
-------
Fig. 34. Nitrogen Purge, Heat No. 14.
-------
Fig. 35. Nitrogen Purge, Heat No. 19.
-------
Fig. 36. Closure Plate, Heat No. 12.
-------
Fig. 37. Closure Plate, Heat No. 13.
-------
•
Fig. 38. Launder Pour, Heat No. 15.
-------
>
D
Fig. 39. Launder Pour, Heat No. 16.
-------
Fig. 40. Canopy Hood, Heat No. 17.
-------
Fig. 41. Canopy Hood, Heat No. 18.
-------
Fig. 42. Slow Pour, Heat No. 20.
-------
4000
c
•H
6
CJ
O
S
o
CO
«
I
2000
102mm
2000
102 mm
Calculated
25 mm Slot Height
100
200
Measured
25 mm Slot Height
51mm
I
100 200
Distance from Slot Opening, mm
Figure 43. Slot Hood Gas Velocity Profiles
113
-------
No Emission Control
20 40
Charging Time, sec.
60
Heat
No. 4 102 mm
No. 6 51 mm
No. 3 25 mm
0
20 40
Charging Time, sec.
Figure 44. Transmittance Results, No Emission
Control and Slot Hood Tests
114
-------
0.1
-------
0.1
v 0.2
u
c
tfl
4J
ii o.4
Ti
c
n)
0.6
0.8
1.0
Closure Plate Heats
20 40
Charging Time, sec,
60
Launder Pour Heats
20 40
Charging Time, sec.
Figure 46. Transmittance Results, Closure
Plate and Launder Heats
116
-------
cu
H
n)
I
(3
tfl
Canopy Hood Heats
20 40
Charging Time, sec.
0)
o
c
0.1
0.2
0.4
2 0.6
H
0.8
1.0
Slow Pour Heat
Heat No. 20
40 80
Charging Time, sec,
120
Figure 47. Transmittance Results, Canopy Hood
and Slow Pour Heats
117
-------
40
40
20
20
il-S
0)
H
O
O
O
3
0)
a1
a)
M
40
20
5.3 12.5
Particle Size, microns
Ho Emission Control-
Calvanize Scrap - Averages
ifor Heats 3, 4, 5 and 6
5.3 12.5
Particle Size, microns
Argon Purging -
Heat No. 10
40
20
5.3 12.5
Particle Size, microns
No Emission Control -
Regular Scrap - Heat No. 9
5.3 12.5
Particle Size, microns
Nitrogen Purging -
Averages for Heats 11-14 and 19
Figure 48. Histograms of Emission Particle Sizes
118
-------
40
40
20
20
o
c
0)
M
J-i
3
U
O
o
5.3 12.5
Particle Size, microns
Closure Plate Heats -
Averages for Heats 12 and 13
5.3 12.5
Particle Size, microns
Launder Pour Heats-
Averages for Heats 15 and 16
0)
er
01
M
40
20
5.3 12.5
Particle Size, microns
Canopy Hood Heats-
Averages for Heats 17 and 18
40
20
5.3 12.5
Particle Size, microns
Slow Pour Heaf
Heat No. 20
Figure49 . Histograms of Emission Particle Sizes
119
-------
SECTION 10
DISCUSSION OF APPLICATIONS OF VARIOUS CHARGING SYSTEMS
INTRODUCTION
As initially envisioned, the intent of this section was to develop a
recommended schematic layout and preliminary performance specifications for
the BOP charging emission control system which had been determined to have
the greatest promise of success. The experimental BOP vessel tests indicated
that four control system concepts had promise, but the results did not show
that any one of the four systems had a significant advantage over the others.
Therefore, this section was modified to be a study of the applications of the
four emission control concepts to new and existing BOP shops.
The object of this section, as redefined, was an evaluation of advantages
and disadvantages from engineering and operating viewpoints of each of the
following system concepts for control of BOP charging emissions:
A Canopy Hood
B Pouring through the main hood by a launder, with the
vessel in the upright position (Launder Pour)
C Closure Plate System
D Slow Hot Metal Pouring
Engineering considerations include space requirements, physical plant
restrictions such as crane limits and building space availability, both for
existing BOP installations and for new plant designs.
Operation considerations include the additional operations required to
operate emission control systems such as control of a closure plate and
possible resultant effects on steel making operations.
DISCUSS::ON
Canopy Hood
Description of Concept—
The canopy hood concept is illustrated diagrammatically in Figure 50.
The canopy hood is an auxiliary hood, separate from the main gas cleaning
120
-------
system hood, that is located and sized to specifically capture charging
emissions. This hood is connected through a system of ductwork and dampers
to a pollution control device (baghouse, electrostatic precipitator or
scrubber) which could be the primary capture system or an independent second-
ary system. This system need be in operation only during hot metal charging.
The canopy hood configuration and the system size must be based on the
anticipated characteristics of the charging emissions.
Defining hood and gas removal system sizes is difficult from the limited
available data. The hood size should be large enough to encompass the plume
and as close to the charging area as possible.
In order to establish design figures for the emission removal system a
factor relating emission volume rates, tonnage and pouring times would be
useful. A logical but unsubstantiated factor relating volume and tonnage is
the emission volume rate divided by the tonnage which assumes that emission
volume is directly related to vessel size. Corrections for scrap types, scrap
hot metal ratios and hot metal characteristics should be included but there
are not enough data available to develop any correlations. Hot metal pouring
times should also be included in the corrections but, again, there are
insufficient data to develop this concept.
Some insight can be gained by evaluating the limited available data with
the volumetric emission rate to tonnage factor. The Weirton Steel BOP tests,
Section 8, showed an average factor of 46 m3/min/tonne and the maximum was
81 m3/min/tonne. An estimate of the pilot BOP emissions based on as estimated
plume size and actual velocity measurements indicated a range of 40 to 70
m-Vmin/tonne. S. Pilkington of British Steel Corporation (see Section 7)
recommended a hood capacity of 170 to 200 m Is for 250 to 300 tonne vessels
which converts to a factor ranging from 33 to 48 m3/min/tonne.
These are the best data available based on actual measurements and
indicated that the emission volume rate to tonnage factor should be in the
range of 33 to 81 m3/min/tonne. This means for a 100 tonne (110 ton) vessel
the fan capacity should be in the range of 3300 m3/min (115,000 CFM) to 8100
m3/min (290,000 CFM) and for a 300 tonne (330 ton) vessel the fan capacity
should be 9900 m3/m (350,000 CFM) to 24000 m3/m (850,000 CFM).
The hood at Hoogovens which was reported to be only 50% effective had a
factor of 4.2 m /min/tonne. The new Inland hood installation has a factor of
22 m3/min/tonne but the roof monitor control system must be included when
evaluating overall system effectiveness. A factor of 17 m /min/tonne was
calculated for the Krupp system but Krupp may be using extended hot metal
pouring times (their system was built by Baumco and Baumco recommends a min-
imum two minute pouring time).
Another important aspect to consider is dilution of the emissions by air
as the emission plume rises. The emission volume therefore will increase
significantly as the distance from the vessel mouth to the hood increases.
Magnitude of this effect is not known.
121
-------
Application to Existing BOP Installations—
In considering the application of a canopy hood to capture charging
emissions in an existing BOP installation, one must first consider the
existing air pollution control (main gas cleaning) system. The survey of BOP
plants showed that the industry-wide use of air pollution control systems is
almost evenly divided between wet scrubbers and electrostatic precipitators.
This survey also indicates that in most of the installations there is no
excess exhaust fan capacity.
The charging emissions are cooled substantially when combined with the
dilution air drawn into the duct system. The temperature of the dirty air can
reach levels below 180°C (350°F) at the inlet to the pollution control equip-
ment, due to cooling in the long duct runs to the equipment which may be
located as far as several hundred meters away from the emission source. Such
low temperature levels can render electrostatic precipitators ineffective as
pollution control equipment since they must operate at temperature levels
between 288° to 316°C (550° to 600°F) to attain maximum dust removal
efficiency. For this reason, baghouses (fabric filters) should be considered
for use for the control of fugitive fumes which are significantly diluted.
Fabric filters are highly effective in removing dust particles as small as
1 micron at operating temperatures up to 200°C (400°F).
If the fan capacity of the main gas cleaning system is adequate, charging
emissions may be channeled from a canopy hood into an existing wet scrubber
system. The main hood, in this case, must be provided with an air damper
which keeps it nearly closed during hot metal charging.
In planning the design and installation of a canopy hood and related
ducting, fans and controls in an existing BOP installation, other important
aspects must be considered as discussed below.
A primary disadvantage of a canopy hood as an emission control device is
possible limits placed on its efficiency due to dimensional restrictions in
hood cor figuration and location. These restrictions can result from the
proximity of crane girders and building steel as well as from furnace charging
clearanc.es. Each shop is unique in clearances to structural steel around the
vessel. Available space may be insufficient and preclude entirely the use of
a canopy hood system. If space is available to install a local hood below the
building; crane girder, clearance diagrams must be developed to determine
possible interferences during scrap and hot metal charging. In addition to
checking crane hood approaches, it may be necessary to consider clearances
for a sc.rap charging machine and its appurtenances. If significant limita-
tions are placed on the capturing efficiency of the local hood, it may be
necessary to install a secondary fume capturing canopy in the roof trusses
above the charging crane.
If the canopy hood is located below the charging crane, it would have to
be designed for flame impingement that could occur during charging. In
additior. the canopy hood design and construction should be sufficiently
strong t.o resist accidental impacts that may occur during scrap charging and
impacts from loads swinging from crane hooks. Hoods should be sectionalized
122
-------
for ease of replacement.
The size of pollution control devices and accompanying equipment required
to remove particulates is generally so large that they must be installed out-
side the shop. A suitable location must be found between existing buildings,
roads, tracks and yard utilities.
Long duct runs are usually involved in the interconnection of the hood
and the pollution control device. Equipment clearance requirements between
cranes, lance handling and flux handling equipment complicates duct routing
and configuration. The choice among routing duct work in roof trusses, along
building columns parallel to the furnace aisle, or buried underground is
dependent on existing conditions. Building members must be analyzed
structurally to determine whether they require reinforcement to carry the
additional load. Loads can result from dust build-up and thermal consider-
ations must be considered as well. Roof members are particularly sensitive
to increased loads.
Electrical power requirements involved in operating a pollution control
system are significant. If sufficient spare capacity is not available, it may
be necessary to install additional transformer capacity and connect to the
plant's high voltage distribution system. It is not uncommon to construct
local control rooms to house high voltage starters, motor control centers and
control panels.
Depending on the nature of the installation, bearing cooling water and
compressed air may be required.
The major advantages of utilizing a canopy hood as a fume capture device
are that: (a) it involves minimum constraints and changes in operating
practices; and (b) auxiliary mechanical and electrical devices required for
the operation of the system can be located away from the immediate harsh
environment of the furnace proper. Other advantages are realized because the
canopy can be utilized for the capture of emissions that result from scrap as
well as hot metal charging. Additionally, the basic system can be expanded
to include furnace tapping and slagging emissions with proper preplanning.
Application to New BOP Installations—
The application of the canopy hood concept for the capture of charging
emissions in the design of a new BOP installation should be considered as a
part of a combined emission control system which would be large enough to
handle the charging, slagging and tapping emissions by means of local canopy
hoods. A system of ductwork and dampers would transmit captured emissions to
a central collection device. With properly designed control, local canopy
hoods could be selectively opened or closed as required for each phase of the
steel production sequence. If pick-up points are operated individually
instead of as a group, the size of the fan and emission control equipment can
be kept to a minimum.
Baghouses (fabric filters) should be considered as the emission control
equipment for this application. The variable gas volumes, low gas temperatures
123
-------
at the control equipment (under 400°F) and the very fine size of the particu-
lates to be captured, make fabric filters a good choice for this application.
Gaseous and particulate emissions from the oxygen blowing cycle would be
collected separately in wet scrubbers or in electrostatic precipitators in
accordance with current practice.
The shape and configuration of canopy hoods and the capacity of the
exhaust fans should be selected to facilitate maximum capture of emissions.
The canopy hood for charging emissions would require additional clearance
above the furnace mouth in the charging aisle. This would involve placing the
crane runway at a higher elevation than current practice. The result would be
to increase the height of the charging aisle. The furnace aisle may have to
be slightly wider than current practice to provide clearance for duct runs.
Launder Pour
Description of Concept—
During the testing and evaluating new methods for capture of charging
emissions in the BOP pilot plant, the application of the launder pour concept
appeared to be very effective. This concept is illustrated on Figure 51.
A launder is used for transferring hot metal from the charging ladle to
the furnace. The hot metal is conveyed by a refractory-lined launder which is
inserted through a port in the lower section of the main exhaust hood. During
hot metal additions, the furnace is in an almost vertical or upright position;
therefore, the charging emissions are captured by the main exhaust hood.
Emissions from the launder, as indicated during the pilot BOP tests, are
minimal.
Application to Existing BOP Installations—
Application of a launder pour system can be considered for any size of
existing BOP furnace. If hot metal can be charged into an upright vessel by
means of a launder through the furnace hood, the shop's existing hoods and
gas cleaning system may possibly be utilized to process emissions released
during charging. Since the type of gas cleaning device, fan performance
characteristics and methods of operation are varied, the applicability of
each shop to this method of charging emission control must necessarily be
verified. Shops with suppressed combustion hood systems have lower exhaust
volume rates and may not be capable of handling the charging emissions.
Hot metal charging through a hood launder requires ladle lifts in excess
of those required for conventional charging. Maximum crane lifts are usually
dictated by scrap charging equipment requirements; existing shops generally
do not have the sufficient crane lift clearance required for hot metal
charging through a hood launder. In addition to crane lift considerations,
clearance and headroom to girders and building steel in the vicinity of the
furnace must be investigated.
In installations in which sufficient building headroom is available, one
or more of the following modifications may be required to accommodate the
124
-------
launder pour concept:
Raise the entire crane runway
Raise the crane trolley runway
Modify the crane hoisting mechanism
Modify crane approaches
Modify hot metal ladle
Reinforce building members to support the launder
The cost of these major modifications and interruptions to production
may preclude the application of this concept in many existing shops.
Installing a launder opening in the hood is a major modification. The
cooling water flow pattern in the hood must not be upset, thus, modifications
must be planned to divert an amount of water around the proposed opening equal
to that which previously passed through the cross section of the opening. It
is suggested that a hinged power-operated closure door be installed to minimize
the opening which hot metal is being charged. Consideration of clearances
must be given for shops that have hood doors for the installation of a furnace
reline tower. The opening could be a section, or portion of the larger door.
Installation of a launder system in a suppressed combustion hood system
is further complicated by the need to seal the hood opening during the blowing
period.
Direct flame impingement on the hood, nearby utilities, and building
members is a concern. Each arrangement must be evaluated and the heat shields
provided as required.
The charging ladle lip could be extended to obtain better approach
dimensions. If the lip is extended, it probably would be necessary to
counter-weight the ladle to provide proper balance. Ladle modifications may
in turn require changes to cranes, transfer cars and clearances, reladling
stations, and ladle reline facilities.
Possible launder arrangements are:
Launder fixed to hood
Launder stand - permanent
Floor-mounted movable launder car
Suspended launder trolley
A launder fixed to the hood has the advantage of not requiring operator
manipulation prior to charging hot metal. Since high temperatures are
125
-------
generated during the production of steel in the launder area, it is essential
that the launder not project permanently into the hood. It may be necessary
to rotate the furnace slightly during charging in order to minimize impinge-
ment of hot metal on the furnace mouth. A fixed launder is susceptible to
damage from tumbling scrap and impact from both the scrap box and the hot
metal ladle. The hood suspension system and guides must be reviewed with
respect to the above impacts as well as the dead load of the launder. Since
it is located above the operating floor, a launder maintenance and inspection
platform with access stairs and proper clearances must be considered.
A portable launder mounted on its own stand is a possibility. The stand
could be spotted and removed from the operating floor by the charging crane
providing this crane's duty cycle permits. This method has the advantage
that fixed projections into the charging aisle are eliminated. In addition,
launder maintenance and inspection can be performed at a remote location. The
disadvantage involves the delay of additional crane moves and the potential
for an increased tap to tap time.
A floor-mounted launder car has the advantage of not requiring crane
moves; however, extensive structural modifications to the charging floor and
its foundations may be required to support the additional equipment.
If sufficient clearances exist in the vicinity of the furnace, a launder
could be suspended from a trolley system attached to the crane and building
girders. The trolley would travel parallel to the girders and the launder
could be indexed in and out of a section of furnace hood that has been pre-
viously opened. The launder trolley could be propelled by a direct drive
motor or cable drawn from a remotely mounted drum. The length of travel
required will probably preclude a cylinder operation. It is believed that the
hood opening location could be selected so the launder will naturally project
into the hood when indexed to the charging position. Interlocks can be
provided to prevent the trolley from indexing unless the hood section has been
opened.
Advantages of the suspended launder trolley system include: (a) the
launder is remotely located during scrap charging; (b) a separately supported
launder minimizes impact transmitted to the hood system; (c) launder
inspection repair or replacement takes place remote from furnace mouth; and
(d) the hood itself and its support system do not have to be designed to
support launder weight. The disadvantages of this system include (a) an
additional piece of mechanical equipment is added to the system and (b) time
would be required to index the launder into position.
A further disadvantage of launder pour hot metal charging is that present
operating procedures must be modified and might result in a productivity
reduction. The crane operator will have to raise the charging ladle between
ten to eighteen feet higher than the present charging practice; visibility
may be a problem because of this change in ladle location. The level of hot
metal in the launder will have to be carefully controlled to minimize spillage
and direct impingement on the hood, the furnace mouth or the lining. Effects
of these procedural changes on the length of charging time and loss of hot
metal temperature cannot be determined until a prototype is in production. An
126
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increase in hot metal temperature loss over that presently experienced could
lower scrap usage. Increases in operating delays for launder repair and the
time to spot the launder may also be significant.
Application to New BOP Installations—
Several departures from current practices for application of the launder
pour concept to a new shop are discussed in the following paragraphs.
Additional clearance above the furnace mouth in the charging aisle will
necessitate placing the crane runway at a higher elevation than is current
practice. To reduce launder length, the furnace should be located as close
to the charging aisle as possible. It is doubtful that the furnace can be
located significantly closer to the charging aisle than in most existing
installations because the location of the furnace center line and the charging
girders is controlled by clearances required for properly positioning of the
lance and the furnace reline tower.
Charging cranes in new shops will require certain changes if the launder
pour is adopted. The hoisting drums will have to be larger because of the
increased lift requirements. Crane cab locations will have to be reviewed in
an effort to achieve the visibility requirements for both scrap and hot metal
charging.
The primary air pollution control system must be designed to handle both
primary blowing and secondary charging emissions. The small quantity of fumes
emanating from the launder may have to be captured by a properly designed
canopy hood. This can be positioned close to the ladle spout. These emissions
can be ducted into the main hood without resorting to a separate control
system. A damper above this canopy hood would open or close the duct con-
necting this hood to the main hood system.
Closure Plate
Description of Concept—
This concept would utilize the shop's existing furnace hoods and gas
cleaning system to capture and process hot metal charging emissions with min-
imum modifications to presently accepted charging techniques. As shown on
Figure 52, this concept involves a retractable closure plate to restrict the
hood intake opening while the furnace is rotated to a position for conven-
tional hot metal charging. A closure plate can be viewed as a horizontal
shutter which moves on a track or guides. When not in use, the closure plate
is retracted and stored on the teeming side of the furnace. For use, the
closure plate is moved to a position below the hood intake leaving only a
small opening on the charging side. The gas cleaning system's induced draft
fan remains in operation drawing air through this small opening. The partial
constriction in the hood intake cross sectional area results in an increased
velocity of air flow through the open portion of the hood intake. This
increased velocity enables the hood to capture the emissions during charging.
127
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A prototype unit has been built and tested at Ford Motor Company to
determine its effectiveness. Tests were also conducted with a similar closure
plate in the BOP pilot plant; these tests demonstrated this concept has promise
if the vessel-hood geometry provides the required velocities and if the hood
has sufficient gas handling capacity.
Application to Existing BOP Installations—
A retractable closure plate could be applied to any vessel size.
Engineering factors which must be considered when installing a closure plate
system £.re: physical clearances, traversing mechanism, interlocking, closure
plate ccoling and wear, and gas removal rate capabilities. Available space on
the tapping side of the furnace may be insufficient and preclude entirely the
installJition of a retractable closure plate. Items that could interfere with
or prohibit its installation include: building columns, hood appurtenances
and supports, coolant scrap chutes, flux chutes and ladle additive equipment.
The existing building structure must be analyzed to determine whether
structural members require reinforcement to carry the additional load.
The minimum distance between the bottom of the hood and the top of the
furnace is approximately the same for an open hood or a retracted closed hood.
This distance is established by furnace rotation clearances and, additionally
in the case of the open hood, fume capture and combustion air requirements..
It is unlikely that this clearance is sufficient to permit furnace rota-
tion wi:h the closure plate in position beneath the hood. Clearance is further
restricted if skull buildup is considered; therefore, it is necessary to
install an interlocking control to preclude closure plate positioning unless
the furiace is rotated to the charging position and to prohibit furnace
righting unless the closure plate is retracted. Additionally, it is essential
that coitrol interlocks preclude oxygen lance lowering when the closure plate
is in position, and prevent closure plate positioning when the lance is
lowered.
The closure plate could be carried on trolley carriages mounted on each
side of the furnace. The traversing would be accomplished similar to that of
a bridge crane. To minimize delay time, a back-up drive system should be
installed to permit closure plate retraction in the event of a primary drive
malfunction. All equipment must be selected to operate in the high ambient
temperature of a furnace area, and expansion provisions must be included in
the design. The traversing mechanisms and their supports must be protected
by heat shields. It is not known if some means of cooling the plate will be
required. If water cooled, a pumping system independent of the hood system
may be required. Flexible hose would be required to permit closure plate
traverse.
Tie closure plate must be designed to resist the impact of skull buildup
that becomes dislodged and falls from within the hood. The design should
be such that skull will be scraped free without jamming as the plate retracts.
Excessive wear of the hood resulting from the impingement of high
velocity captured charging emissions is not believed to be a problem. The
128
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entrained particulates and the conditions occurring during the short charging
period should be less severe than those existing during the longer oxygen
blowing period. However, it is necessary that the closure plate be fabricated
of substantial stock for operation in the harsh environment of a steel making
facility.
A disadvantage of this concept is the time delay incurred while position-
ing the closure plate after the furnace has been rotated to the charging
position and the ensuing delay to retract the closure plate prior to righting
the furnace after charging. This sequence of operations must be followed in
most, if not all, existing shops because existing clearances will preclude
furnace rotation with the closure plate positioned. The time required for
positioning and retracting the closure plate would tend to increase tap to
tap time. Scheduled maintenance could be performed during furnace reline
periods; however, additional maintenance delays are inevitable when additional
equipment is introduced into the operating cycle.
Application to New BOP Installations—
Installation of a closure plate system in a new BOP shop would be
relatively easy provided that the vessel-hood geometry was satisfactory and
the primary gas cleaning system has sufficient capacity. Attention to
structural design to eliminate clearance problems as discussed above would be
necessary. A thorough review of results of systems now being evaluated is
suggested.
Slow Hot Metal Pouring
A test with the BOP pilot plant to evaluate the effects of slow hot metal
pouring rates during charging showed that a slow hot metal pouring rate can
diminish emission rates.
The slow hot metal pouring rate would have a definite impact on steel
production output in the BOP steel making process since production rate is
primarily a function of the time involved in completing the tap-to-tap cycle
of the furnace.
A typical BOP average tap-to-tap time is 45 minutes. Increasing the hot
metal pouring time by 1 minute would increase this time to 46 minutes and the
productivity would be reduced by 2.2%. Pouring time increases of 2, 3 and 4
minutes would decrease productivity by 4.3, 6.2 and 8.2%, respectively. The
consequences of this can be far reaching. Each production unit in a modern
integrated steelworks is designed to operate at a rate dictated by the pro-
duction unit ahead of it. Thus, if the steelworks productivity were cut,
each of the subsequent production units such as the hot rolling mills, cold
rolling mills and finishing lines would be forced to operate at less than
optimum design rates resulting in energy and manpower inefficiencies.
Similarly, the coke ovens and blast furnaces would have to limit production
to meet reduced BOP demands.
129
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SUMMARY
Canopy Kood Concept
The canopy hood concept utilizes an auxiliary hood separate from the main
gas cle?:ning system hood that is located and sized to capture charging
emissions. This hood is connected through a system of duct work and dampers
to a pollution control device which removes particulates from the captured
fumes. This canopy hood system would be in operation only during hot metal
charging.
The: application of the canopy hood concept to an existing or new BOP
installation will require the accurate prediction of fume volumes, velocities
and composition for a variety of hot metal charging operations. Since these
conditions are not completely predictable, the design of canopy hood systems
to capture charging emissions from BOP furnaces would be difficult. Available
data indicate that the emission volume rate required divided by the vessel
size should be in the range of 33 to 81 m3/min/tonne (1100 to 2600 CFM/ton).
The application of a canopy hood will require consideration of the type of
existing air pollution control system and existing fan capacity, and dimen-
sional restrictions and operating clearances unique to individual shops. Major
advantages of the canopy hood concept are that it would involve minimum con-
straint:; and changes to operating practices, and that no auxiliary mechanical
or electrical devices are required in the immediate vicinity of the furnace.
Launder Pour
This concept utilizes a launder to transfer hot metal from the charging
ladle to the furnace. The hot metal is conveyed by gravity along a refractory-
lined launder which is inserted through a port in the lower section of the
main exhaust hood. During hot metal additions, the furnace would be in an
almost vertical or upright position and, therefore, the charging emissions
would be captured by the main exhaust hood.
The application of the launder pour concept will require a verification
that the existing main gas cleaning system will handle charging emissions,
design changes to the hood and its cooling system, the determination if
sufficient headroom is available for the change in ladle pouring position and
the design of the launder arrangement. Procedural changes will be required
which may reduce productivity.
Closure Plate
The closure plate concept utilizes a retractable closure plate to
restrict the main hood intake opening while the furnace is located at the
position for conventional hot metal charging. The partial restriction in
hood intake cross-sectional area results in an increased velocity of air flow
through the open portion, thus enabling the hood to capture charging emissions
for cleanup by the shop's main gas cleaning system.
The application of the closure plate concept will require verification
that the gas cleaning system can handle charging emissions and an examination
130
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of the physical clearances available in the shop. Operation with a closure
plate may result in delays in the production cycle and, since this mechanism
is operated in the harsh furnace environment, maintenance problems may be
anticipated.
Slow Hot Metal Pouring
Tests performed with the BOP pilot plant indicated that the use of slower-
than-normal rates of hot metal pouring during charging resulted in a lower
emission rate but did not indicate that the total amount of emissions was
reduced.
The slow hot metal pouring rate would have an impact on the production
output of a BOP plant since production efficiency is a function of the tap-to-
tap cycle time of the furnace. An increase in hot metal charging time of 1
minute would reduce productivity by 2.2%.
131
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.RJRNACE
CHARGING AISLE
CRANE GIRDER
CANOPY HOOD
CHARGING
LADLE
FIG 50 CANOPY HOOD CONCEPT
132
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FURNACE AISLE
_u JL XRANE GIRDER
CHARGING AISLE
CHARGING
LADLE
FIG si LAUNDER POUR CONCEPT
133
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FURNACE
CHARGING AISLE
CRANE
GIRDER
RETRACTED.
pqsmoN__/
CLOSURE
PLATE
CHARGING
LADLE
FIG 52 CLOSURE PLATE CONCEPT
134
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SECTION 11
APPENDIX A
SPARK SOURCE MASS SPECTROMETRIC ANALYSIS
OF SIZED PARTICULATE SOURCE SAMPLES
Report SS004
E. Hunter Daughtrey, Jr.
January 13, 1976
135
-------
FOREWORD
A series of sized particulate samples, collected on commercial aluminum
foil, weire analyzed for selected elements by spark source mass spectrometry.
Evaluation of techniques for removal of sample from the aluminum foil
collector was also performed.
This work was performed under Work Order 1.7 of contract //68-02-1567 in
support of the Environmental Monitoring and Support Laboratory, Environmental
Research Center, Research Triangle Park, North Carolina (T.D. 1.7-4, T.I. //4).
EXPERIMENTAL
1.1 Sariple pretreatment
The samples received were originally collected via cascade impactor for
a weighl:-particle size distribution determination. Samples were crumpled
inside t:he aluminum foil collector. Each foil plus sample was stored in a
small plastic petri dish. The interior of some of the dishes contained par-
ticulate, indicating some sample loss from the foil. Sample sizes were small,
0.005-2.2 mg; therefore, each sample was taken for analysis in its entirety.
Renoval of the sample from the foil was performed by EPA personnel by
ultrasoriicating the foil for 15 minutes in an ultrasonic cleaner in 5 milli-
liters of either pesticide grade benzene or ultrapure nitric acid. The sample
in the extraction liquid was delivered to this laboratory in a capped plastic
test tube.
The sample was briefly suspended in its extraction liquid by use of a
vortex nixer and immediately poured over a weighed amount of spectrographic
grade graphite. The liquid was evaporated under an infrared lamp, and 0.5
millilitier of 100 ppm Erbium internal standard was added to the graphite
sample nixture and likewise evaporated. Sample residue from the test tube was
rinsed into the mixture using a minimum volume of either pesticide grade
benzene or deionized water. The graphite sample mixture was thoroughly dried
and mixed using a mixing mill. The resultant mixture was used to prepare a
set of electrodes for each sample.
1.2 SSHS Analysis
A series of 14 graded exposures (10~^ - 300 nC) in steps of a factor of
3 were taken by photoplate for each sample. The photoplates were developed,
then evaluated by microdensitometer, and the peak optical density, after
correction for the mass dependent effects of dispersion and emulsion response,
was converted to relative exposure via the Churchill two-line calibration
136
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method. Calculation of sample concentration was done using the general SSMS
formula. A correction was made for differences in relative sensitivity using
coefficients calculated from the analysis of SRMs and other analyzed materials
of similar composition.
RESULTS AND DISCUSSION
2.1 Preliminary Experiments
Due to the small sample size, it was necessary to establish the back-
ground level of the sought-for elements. Table A-l gives the micrograms of
each element found in the analysis of the nitric acid and benzene blanks. The
values are not expressed as concentration in the solvent, as this would imply
that the contamination is due to the solvent itself, which is unlikely due to
the grade of solvents employed. Contamination is more likely from sample
manipulation, even though great pains are taken to prevent this (plastic
labware for the pretreatment steps, teflon spatulas for mixing and electrode
fabrication, clean boxes, and source cleaning of the mass spectrometer). All
of the elements sought are relatively common and could be expected to show
s ome contamination.
To estimate the contribution from the aluminum foil collector, a 1.5 cm
diameter circle of commercial-grade aluminum foil was ultrasonicated with 5
milliliters of HNC^. No blank aluminum foil collectors were supplied for
analysis. The only element appearing above background was the major constitu-
ent aluminum.
Two methods of removing the sample from the foil were evaluated. Benzene
was initially tried, as its inertness might allow the determination of
aluminum in the sample without contribution from the foil. However, recovery
studies, performed by giving the foil a second ultrasonic wash with HNC^, show
that the efficiency of the benzene removal is erratic and generally low.
Evidence is presented in Table A-2. A similar study for HNO-j shows a much
higher and more consistent removal of the sample with one wash. The results
of this study are given in Table A-3. Therefore, nitric acid was used for the
bulk of the analyses. Nitric acid also yielded an advantage in improved
electrode homogeneity since it dissolved several of the elements in the sample.
2.2 Analyzed Elements
The following elements were those requested for analysis in the task
instructions. No other elements were observed at a significant concentration
level.
A. Sodium - mass 23 used for analysis; 44% RSD; no interference but ease of
ionization by competing mechanisms adds to uncertainty.
B. Magnesium - mass 25 used for analysis; 43% RSD; possible and likely inter-
ference from 12C13C+, check of mass 25/26 ratio was close to 25Mg+/26Mg+
ratio.
C. Aluminum - not analyzed due to interference from collector foil.
137
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D- Silicon - mass 28 used for analysis; 28% RSD; possible slight interference
from ibFe+.
E. Sul::ur - not determined; severe interference from 1602+(32) and 64Zn2+(32) ,
3) and
F. Potassium - mass 39 and 41 used for analysis; 34% RSD; same type of
ionizat:Lon effects as sodium.
G. Calcium - mass 40 used for analysis; 34% RSD; no interference problems.
H. Manganese - mass 55 used for analysis; 29% RSD; no interference problems.
I. Iron - masses 56 and 57 used for analysis; 17% RSD; possible slight inter-
ference "from 28Si2+ and 168Er3+(56) and 2S>29Si2+(57) . Since iron is largest
component of sample, effect is minimal.
2 i
J. Zinc - masses 64, 67, and 68 used for analysis; 12% RSD; S^ possible but
unlikely interference.
K. Lead - masses 206, 207 and 208 used for analysis; 17% RSD; no interference
problems:.
The uncertainty expressed here as its relative standard deviation is a
statement of the precision of the reported SSMS analysis of the same sample
(from varying exposures of the same photoplate) . It has been shown for
duplicate electrodes of the same material and sample pretreatment that this
approximates the RSD of duplicate electrodes. In this case, it would not
reflect the uncertainty of sampling and sample pretreatment, as the analysis
of duplicate samples would. Sample size precluded this. Therefore, overall
precision is expected to be somewhat poorer.
2. 3 Results of Analysis
The results of the analysis of the sized particulates are given in
Tables A- 4 through A- 12. The value in parenthesis is the limit of detection.
determined from the standard deviation of the blank value. It is included
as an additional index of the reliability of each datum.
REFERENCES
[1] Ahearn, A. J. (ed.), Mass Spectrometric Analysis of Solids, Elsevier,
Amsterdam, (1966).
[2] Ahearn, A. J. (ed.), Tra.ce Analysis by Mass Spectrometry , Academic Press,
New York, (1972).
[3] Cuirrie, L. A., Analytical Chemistry 40 (3), 587 (1968).
138
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TABLE A-l. ANALYSIS OF NITRIC ACID AND BENZENE BLANKS
Weight Found, Micrograms*
Elements
Na
Mg
Si
K
Ca
Mn
Fe
Zn
Pb
HNO-
Benzene
1.15
3.5
2.6
.13
.6
.055
2.4
.095
.40
1.3
3.35
14.8
.24
.5
.175
9.75
.55
0
*Sample size 5 ml
TABLE A-2. EXTRACTION EFFICIENCY OF BENZENE
Sample 2A
Wt. Extracted
Micrograms
Na
Mg
Si
K
Ca
Mn
Fe
Zn
Pb
4
0
.5
.9
0.06
0.2
.1
2.5
0.4
0.1
HNO-3
0.1
1.2
.7
0.03
0.7
.2
2.6
0:.4
0.2
Eff1
0
29
56
67
22
33
49
50
33
Sample 4A
Sample ISA
Wt. Extracted
Micrograms %
4
0
0.9
0.4
0.03
0.1
0.02
0.6
0.1
0.05
HN03
0.02
.07
0.26
0.02
0.3
0.03
0.7
0.1
0.06
Eff
0
93
61
60
25
40
46
50
45
Wt. Extracted
Micrograms %
4
1.4
1.6
4.8
0.3
0.4
0.06
92
9
9.9
HN03
0.3
0.3
0.9
0.06
0.1
0.08
2.3
0.7
0.4
Eff
82
84
84
83
80
43
97
93
96
(1) Assuming 100% removal by HN03 plus benzene extraction,
Designates benzene extraction.
139
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TABLE A-3. EXTRACTION EFFICIENCY OF NITRIC ACID
ID 2C
1st 2nd 1st 2nd
Extract Extract % Eff1 Extract Extract % Eff
Na
Mg
Si
K
Ca
Mn
Fe
Zn
Pb
1.5
1.2
4.0
0.3
1.7
0.3
4.6
1.0
0.2
0.4
1.0
1.5
0.1
0.3
0.03
1.3
0.02
0
79
54
73
75
85
91
78
98
100
1.5
3.0
6.5
0.5
2.0
0.6
13.2
3.3
1.8
1.5
2.0
7.8
0.1
0.3
0.1
4.1
0.1
0
50
60
45
83
87
86
76
97
100
1. Assuming all sample is removed in two treatments.
TABLE A-4. TEST RESULTS - HEAT 1
Concentrations, Wt. %
Sample
Element
Na
Mg
Si
K
Ca
A B
No 9.8
Sample (2.0)
6.9
(6.2)
30 . 8
(3.0)
2.2
(0.2)
3.5
(0.8)
C
3.7
(2.3)
16.8
(7.0)
19.3
(3.4)
2.7
(0.2)
3.1
(1.0)
D*
1.9
(0.6)
2.2
(1.0)
5.5
(0.5)
0.4
(0.03)
1.0
(0.13)
E
<(!.!)
4.3
(1.6)
4.1
(0.8)
0.3
(0.04)
2.6
(0.2)
Mn
Fe
Zn
Pb
Sample Wt.
Milligrams
0.4 1.0 0.33 0.10
(0.06) (0.07) (0.015) (0.016)
21.5
(1.6)
18.6
(1.8)
10.8 3.3
(0.05) (0.05)
5.9
(0.25)
2.3
3.1
(0.4)
0.30
2.0
(0.3)
3.1
(0.3)
(0.007) (0.01)
.2
(0.04)
0.08 0.07 0.52
*Sum of the nitric acid extractions.
140
0.31
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TABLE A-5. TEST RESULTS - HEAT 2
Concentrations, Wt. %
Sample
Element
Na
Mg
Si
K
Ca
Mn
Fe
Zn
Pb
A* B
0.1 No
(0.1) Sample
1.7
(0.3)
1.6
(0.2)
0.09
(0.01)
0.9
(0.04)
0.3
(0.003)
3.1
(0.09)
0.8
(0.003)
0.3
(0.01)
c**
3.0
(1.0)
5.0
(2.9)
14.3
(1.4)
0.6
(0.08)
5.4
(0.4)
1.65
(0.03)
17.8
(0.8)
3.4
(0.02)
1.8
(0.13)
D
4.0
(3.0)
7.4
(9.9)
9.0
(5.0)
1.4
(0.3)
0.70
(1.3)
1.5
(0.1)
16.8
(2.6)
6.6
(0.08)
2.0
(0.44)
E
No
Sample
M
"
it
M
it
"
it
ii
Sample Wt. 1.46
Milligrams
0.17
0.05
*Sum of benzene and nitric acid extracts.
**Sum of nitric extracts.
141
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TABLE A-6. TEST RESULTS - HEAT 3
Concentrations, Wt. %
Sample
Element A B C D E
Na No No No 2.7 0.8
Sample Sample Sample (1.5) (0.4)
Mg " " " 4.4 2.0
(4.5) (1.3)
Si " " " 5.3 5.3
(2.2) (0.6)
K " " " 1.2 1.1
(0.13) (0.04)
Ca " " " 0.5 0.4
(0.6) (0.2)
Mn " " " 0.6 0.5
(0.04) (0.01)
Fe " " " 14.1 12.8
(1.2) (0.35)
Zn " " " 2.8 2.5
(0.03) (0.01)
Pb " " " 0.51 0.5
(0.2) (0.06)
Sample Wt. 0.11 0.37
Milligrams
142
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TABLE A-7. TEST RESULTS - HEAT 4
Concentrations, Wt. %
Sample
Element
Na
Mg
Si
K
Ca
A*
<(0.08)
0.97
(0.2)
0.66
(0.12)
0.05
(0.01)
0.4
(0.04)
B
1.1
(0.3)
2.8
(0.9)
3.8
(0.4)
0.4
(0.02)
2.9
(0.12)
C
0.7
(0.4)
7.3
(1.3)
7.0
(0.6)
0.2
(0.04)
4.3
(0.18)
D
0.3
(0.1)
2.2
(0.3)
0.2
(0.01)
1.9
(0.05)
E
0.1
(0.2)
4.1
(0.6)
2.8
(0.3)
0.05
(0.02)
1.6
(0.08)
Mn 0.05 0.4 0.3 0.3 0.1
(0.003) (0.009) (0.013) (0.004) (0.006)
Fe 1.3 9.2 6.0 20.6 3.2
(0.07) (0.2) (0.35) (0.09) (0.17)
Zn 0.2 2.1 1.4 1.3 .4
(0.002) (0.007) (0.01) (0.003) (0.005)
Pb 0.11 0.8 0.5 0.5 0.1
(0.01) (0.04) (0.06) (0.016) (0.03)
Sample Wt. 1.91 0.54 0.37 1.39 0.78
Milligrams
*Sum of benzene and nitric acid extracts.
143
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TABLE A-8. TEST RESULTS - HEAT 6
Concentrations, Wt. %
Sample
Element A B C D E
Na No
Sample <(0.4) <(0.8) <(0.3) <(0.3)
Mg " 2.0 3.8 1.2 1.8
(1.1) (2.3) (0.9) (0.9)
Si " 1.2 2.5 2.6 2.5
(0.5) (1.1) (0.4) (0.4)
K " 0.08 0.3 0.16 0.15
(0.03) (0.07) (0.02) (0.02)
Ca " 1.0 2.8 1.9 4.0
(0.15) (0.3) (0,12) (0.12)
Mn " 0.1 0.2 0.2 0.2
(0.01) (0.02) (0.009) (0.009)
Fe " 2.9 5.7 3.9 4.8
(0.3) (0.6) (0.2) (0.2)
Zn " 0.4 0.7 0.8 0.5
(0.008) (0.018) (0.007) (0.007)
Pb " 0.1 0.2 0.1 0.1
(0.05) (0.1) (0.04) (0.04)
Sample Wt. 0.45 0.21 0.57 0.54
Milligrams
144
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TABLE A-9. TEST RESULTS - HEAT 9
Concentrations, Wt. %
Sample
Element A B C D E
Na 0.15
(0.3) <(0.5) <(0.9) <(0.9) <(1.3)
Mg 1.4 2.0 3.7
(0.9) (1.6) (2.6) <(2.6) <(3.8)
Si 3.5 2.4 4.5 1.3
(0.4) (0.8) (1.3) (1.3) <(1.8)
K 0.2 0.2 0.2 0.2 0.5
(0.03) (0.04) (0.07) (0.07) (0.1)
Ca 0.9 0.9 0.9
(0.1) (0.2) (0.35) <(0.35) <(0.5)
Mn 0.4 0.1 0.3 0.1 0.1
(0.01) (0.016) (0.026) (0.026) (0.04)
Fe 14.0 5.5 13.0 4.5 3.8
(0.2) (0.4) (0.7) (0.7) (1.0)
Zn 2.7 1.6 2.7 2.6 2.6
(0.007) (0.012) (0.02) (0.02) (0.03)
Pb 1.5 1.2. 0.9 3.0 1.7
(0.04) (0.07) (0.1) (0.1) (0.17)
.Sample Wt. 0.53 0.31 0.19 0.19 0.13
Milligrams
145
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TABLE A-10. TEST RESULTS - HEAT 12
Concentrations, Wt. %
Sample
Element A B C D E
Na 0.4 2.1
<(0.4) (1.0) <(3.3) <(1.0) <(3.3)
Mg 3.1
<(1.0) (3.1) <(9.9) <(2.9) <(9.9)
Si
K 0.4 0.2 0.2
<(0.03) (0.09) (0.3) <(0.08) (0.3)
Ca 0.8
<(0.14) (0.4) <(1.3) <(0.4) <(1.3)
Mn 0.04 0.2 0.4
(0.01) (0.03) (0.1) <(0.03) <(0.1)
Fe 1.3 10.0 10.0 0.3
(0.3) (0.8) (2.6) (0.8) <(2.6)
Zn 0.1 0.86 0.5 0.04 0.04
(0.008) (0.02) (0.08) (0.02) (0.08)
Pb 0.2 0.5
(0.05) (0.14) <(0.4) <(0.13) <(0.4)
Sample Wt. 0.47 0.16 0.05 0.17 0.05
Milligrams
146
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TABLE A-ll. TEST RESULTS - HEAT 15
Concentrations, Wt. %
Sample
Element
Na
Mg
Si
K
Ca
A*
1.7
(0.07)
1.9
(0.2)
5.7
(0.10)
0.4
(0.01)
0.5
(0.03)
B C
0.08
<(0.2) (0.17)
«0.5) «0.5)
0.4
<(0.25) (0.24)
0.03 0.15
(0.01) (0.01)
0.07
<(0.07) (0.07)
D
0.06
(0.12)
«0.«
0.08
(0.18)
0.09
(0.01)
<(0.05)
E
«0.5>
«1.5>
0.6
(0.7)
0.19
(0.04)
<(0.20
Mn 0.1 0.03 0.06 0.04 0.1
(0.002) (0.005) (0.005) (0.004) (0.015)
Fe 94.3 1.0 1.62 0.8 3.0
(0.06) (0.1) (0.13) (0.1) (0.4)
Zn 9.7 0.4 1.1 1.2 1.3
(0.003) (0.004) (0.004) (0.003) (0.01)
Pb 10.3 0.3 0.4 0.5 0.2
(0.01) (0.02) (0.02) (0.016) (0.07)
Sample Wt. 2.23 0.96 1.00 1.36 0.33
Milligrams
*Sum of benzene and nitric acid extracts.
147
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TABLE A-12. TEST RESULTS - HEAT 17
Concentrations, Wt. %
Sample
Element A B C D E
Na 0.4 1.1
(0.2) <(0.6) (1.0) <(!.!) <(2.8)
Mg 1.1 1.3 5.9
(0.7) (1.7) (2.9) <(3.3) <(8.2)
Si 3.4 2.6 5.4
(0.4) (0.8) (1.4) <(1.6) <(4.0)
K 0.3 0.3 0.5 0.2 0.8
(0.02) (0.05) (0.08) (0.1) (0.2)
Ca 0.8 0.3 0.7
(0.1) (0.2) (0.4) <(0.4) <(!.!)
Mn 0.3 0.2 0.3 0.04 0.2
(0.01) (0.02) (0.03) (0.03) (0.08)
Fe 12.2 5.0 13.3 1.0
(0.2) (0.5) (0.8) (0.9) <(2.2)
Zn 3.1 1.6 2.3 1.8 3.3
(0.006) (0.01) (0.02) (0.02) (0.06)
Pb 1.1 0.2 0.6 0.2 0.4
(0.03) (0.08) (0.13) (0.15) (0.4)
Sample Wt. 0.67 0.29 0.17 0.15 0.06
Milligrams
148
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SECTION 12
APPENDIX B
STATISTICAL ANALYSIS OF BOP CHARGING
EMISSION STUDY
Gerald Shaughnessy
University of Dayton
Research Institute
Dayton, Ohio 45469
October 1974
Prepared for:
Control Systems Laboratory
National Environment Research Center
Research Triangle Park, N.C. 27711
149
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STATISTICAL ANALYSIS OF BOP CHARGING
EMISSION STUDY
This report describes University of Dayton Research Institute's (UDRI)
contribution to the statistical analysis of the data collected for the BOP
charging emission study for tests conducted at Weirton Steel Division BOP
Shop. The original data is given in Tables 7, 8 and 11.
The charging operations were carried out using various charge materials
and pour rates and covered a wide range of operating parameters. A statisti-
cal analysis was first carried out on the grain loading data. The following
table gives the correlations between grain loading and various operating
parameters.
Matrix of Correlation Coefficients
% of Charging Grain
Scrap Charge Time Temperature Loading
% of Test 1 .029 -.148 .414
Scrap in
Charge
Charging .029 1 .80 -.166
Time
Temperature -.148 .80 1 -.276
Grain Loading .414 -.166 -.276 1
The: parameter that has the largest correlation with grain loading is
percent of test scrap in the charge. This value varied from 2.1 percent to
15.7 percent with all of the large values associated with the dealers yard
scrap. This makes it extremely difficult to determine if the large values of
grain loading for Dealers Yard scrap are due to the scrap type or to the large
percentage of test scrap in the charge.
The: following table gives the average grain loading for the four scrap
types.
Scrap Types
Clean Galvanized Oily Dealers Yard
Mean Grain Loading 4.46 2.93 11.7 10.85*
*Does not include a grain loading of 214.4 for sample number 13.
150
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To determine if these observed differences are statistically significant
an analysis of covariance was performed. The analysis of covariance com-
pensates for the fact that other operating parameters are varying over a wide
range during the test runs. Specifically the analysis took into account the
changing values of three parameters, percent of test scrap, charging time, and
temperature. The results of the analysis of covariance showed an F = 2.01
which is not quite significant at the 10 percent significance level. This
means that if there were no differences between the grain loadings for
different types of test scrap the probability of observing average loadings
as different as those observed is slightly larger than 10 percent. A reason-
able conclusion to draw from the analysis is that the data collected gives
some evidence that the cleaner charging materials produced less emission than
the dirtier materials, but the evidence is not statistically conclusive. If
more tests are to be run care should be taken to try to hold the percent of
test scrap used at as constant a value as possible. Also if possible, more
tests should be run with the different types of test scrap to give a more
sensitive statistical test. The one grain loading value for sample number 13
was 214.4. This value was not included in the statistical analysis but it
should be noted that loadings of this magnitude can occur.
A similar type of analysis of covariance was performed to determine if
the scrap type produced significant differences in the variables, total hydro-
carbons and particle size.
For total hydrocarbons the following correlations were found.
% of Charging Total Hydro-
Scrap Charge Time Temperature carbons (gaseous)
% of Scrap 1 .062 .118 .12
Charge
Charging .062 1 .793 -.375
Time
Temperature -.12 .793 1 -.502
Total Hydrocarbons .12 -.375 -.502 1
(gaseous)
The F statistic for the analysis of covariance for total hydrocarbons
gaseous was F = 3.01 with 3 and 5 degrees of freedom. The larger the value of
the F statistic the more evidence is in the data that there is a difference
in the gaseous hydrocarbons among scrap types. The F value of 3.01 is not
quite significant at the 10 percent significance level. It would have to
exceed 3.62 to be significant. Again a reasonable interpretation of the
analysis would be that the data gives some indication that there is a rela-
tionship between scrap type and total hydrocarbons gaseous, but the data is
not conclusive and more testing with more samples would be needed to give
conclusive results. The F value for total hydrocarbons particulate was 1.5
which indicates that the data does not show a relationship between total hydro-
carbons particulate and scrap type. The analysis for particle size was done
151
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for the mass median diameter only. The F value for this analysis was less
than l.C and thus no differences in particle size for mass median diameter
between scrap type are indicated. This analysis did not include the large
observation for run 13.
The. data for the Hy-vol particulate analysis is given in Table 9. An
analysis, of this data by scrap composition was performed using the technique
of Analysis of Variance. The Analysis of Variance will indicate if the
chemical composition of the particulate is dependent on scrap type. Table B-l
gives the average values for the particulate analysis (Wt. %) for different
scrap composition.
An Analysis of Variance was then performed for those compositions where
a difference among scrap type was indicated. The results of the analysis are
given for each chemical composition.
Analysis; for Zn
ANOVA TABLE:
ITEM:
GRAND TCITAL
GRAND MLAN
TREATMENTS
ERROR
SS
524.2
383.042
111.269
29.8887
DF
15
1
3
11
MS
37.0897
2.71715
F = 13.6502 ON 3 AND 11 DEGREES OF FREEDOM.
EXACT PROB. OF F = 13.6502 WITH (3, 11) D.F. IS .00076
Analysiji for Pb
ANOVA TABLE:
ITEM:
GRAND TOTAL
GRAND MI1AN
TREATMENTS
ERROR
SS
11.55
6.53399
4.90267
.113336
DF
15
1
3
11
MS
1.63422
.103032F-01
F = 158,612 ON 3 AND 11 DEGREES OF FREEDOM.
EXACT PROB. OF F = 158.612 WITH (3, 11) D.F. IS 0
152
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Analysis for Fe
ANOVA TABLE:
ITEM: SS DF MS
GRAND TOTAL 1765.27 15
GRAND MEAN 1184.59 1
TREATMENTS 364.708 3 101.569
ERROR 275.969 11 25.0881
F = 4.04852 ON 3 AND 11 DEGREES OF FREEDOM.
EXACT PROB. OF F = 4.04852 WITH (3, 11) D.F. IS .03608
Analysis for Mg
ANOVA TABLE:
ITEM: SS DF MS
GRAND TOTAL 10.3 15
GRAND MEAN 8.36266 1
TREATMENTS .968998 3 .329666
ERROR .948335 11 .862122F-01
F = 3.82369 ON 3 AND 11 DEGREES OF FREEDOM.
EXACT PROB. OF F = 3.82389 WITH (3, 11) D.F. IS .04202
Analysis for Ca
ANOVA TABLE:
ITEM: SS DF MS
GRAND TOTAL 128.06 15
GRAND MEAN 109.89 1
TREATMENTS 9.3694 3 3.12313
ERROR 8.80008 11 .800007
F = 3.90388 ON 3 AND 11 DEGREES OF FREEDOM.
EXACT PROB. OF F = 3.90388 WITH (3, 11) D.F. IS .03978
153
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Analysis for Si
ANOVA TABLE:
ITEM: SS DF MS
GRAND TOTAL 251.35 15
GRAND MEAN 212.616 1
TREATMENTS 21.1917 3 7.0639
ERROR 17.3419 11 1.57654
F = 4.48064 ON 3 AND 11 DEGREES OF FREEDOM.
EXACT PROS. OF F = 4.48064 WITH (3, 11) D.F. IS .02724
Analysis for Fe+3
ANOVA TABLE:
ITEM: SS DF MS
GRAND TOTAL 1801.52 15
GRAND MEAN 1512.02 1
TREATMENT 39.5959 3 13.1806
ERROR 849.901 11 22.7182
F <.580972 ON 3 AND 11 DEGREES OF FREEDOM.
EXACT PROB. OF F = .580972 WITH (3, 11) D.F. IS .6426
Analysis for Fe+2
ANOVA TABLE:
ITEM: SS DF MS
GRAND TOTAL 3455.62 15
GRAND MEAN 2758.1 1
TREATMENTS 172.489 3 57.4962
ERROR1 . 525.027 11 47.7297
F = 1.20462 ON 3 AND 11 DEGREES OF FREEDOM.
EXACT PROB. OF F = 1.20462 WITH (3, 11) D.F. IS .35385
154
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TABLE B-l.
Average Percent Weight Particulate
Type Fe+3 Fe+2 Fe Ca Mg S^^lNa. K Pb Zn Mn
Clean 8.27 12.6 13.11 3.53 1.05 5.22 7.15 .3 .183 .3 2.45 .77
Galvanized 12.57 8.13 3.03 1.86 0.5 2.63 1.7 .15 .08 .2 4.23 .23
Oily 10.6 16.7 11.33 2.9 0.67 2.97 2.1 .1 .13 .77 6.57 .467
Dealers Yard 10.5 17.63 3.83 1.7 .467 2,8 2.1 .16 .13 1.73 9.6 .50
Ln
Ui
-------
On the analysis of variance table a large F-value indicates that there
are probably real differences in chemical composition among the different
scrap type. Only in Fe+^ and Fe+2 does there appear to be no differences due
to scrap type.
Correlations were also calculated between the values for hot metal com-
position and particulate analysis (Wt. %). No significant correlations were
found.
Conclusion
The results of the statistical analysis indicate that there probably are
differences in grain loading among scrap type, but that the observed data is
not conclusive enough to be statistically significant. Further tests would
seem to be warranted, but a statistical design should be used to determine
adequate sample numbers and methods of controlling variation in other
operatir.g parameters. The analysis indicates that percent of scrap charge
may be £.n important variable and its values should -be carefully considered in
future £:xperiments.
The analysis of the chemical composition of the particulate showed
significant differences for most chemicals among the different scrap types.
Table B--1 gives the mean weight for each chemical for each scrap type. The
Analysis, of Variance tables show that in most cases the chemical composition
of the particulate will not be the same for all scrap types. The analysis of
correlation between hot metal analysis and chemical composition of the
particulate, showed no significant correlations.
There are some trends that appear in the data of this experiment, such as
differences in grain loading being related to scrap type, that suggest that
further experimentation should be carried out, if a conclusive judgement is to
be made concerning the validity of these trends. If similar experiments of
this type are to be carried out a statistical design of the experiment should
be used to determine necessary sample numbers and.to determine the best
methods for handling other operating parameters. If a good statistical
design :Ls used in future experiments more information should result from any
data collected.
156
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
. REPORT NO.
EPA-600/2-77-218
2.
3. RECIPIENT'S ACCESSION NO.
. TITLE ANDSUBTITLE
Development of Technology for Controlling BOP
Charging Emissions
5. REPORT DATE
October 1977
6. PERFORMING ORGANIZATION CODE
. AUTHOR(S)
8. PERFORMING ORGANIZATION REPORT NO.
K.E. Caine, Jr.
'. PERFORMING ORGANIZATION NAME AND ADDRESS
National Steel Corporation
Research and Development Department
P.O. Box 431
Weirton. West Virginia 26062
10. PROGRAM ELEMENT NO.
1AB604; ROAP 21AQR-05
11. CONTRACT/GRANT NO.
68-02-1370
12. SPONSORING AGENCY NAME AND ADDRESS
EPA, Office of Research and Development
Industrial Environmental Research Laboratory
Research Triangle Park, NC 27711
13. TYPE OF REPORT AND PERIOD COVERED
Final: 6/73-12/76
14. SPONSORING AGENCY CODE
EPA/600/13
15.SUPPLEMENTARY NOTES jERL-RTP project officer for this report is Robert C. McCrillis,
Mail Drop 62, 919/541-2733.
16. ABSTRACT The repOrt gives results of 2i study of the basic oxygen process (BOP) hot
metal charging emission control technology, conducted with a 900 kg pilot vessel
designed for the experiments. Complete instrumentation was provided to measure
the emissions, the effectiveness of the various systems investigated, and the BOP
operating parameters. Twenty heats were made: four had no emission controls oper-
ating, to establish base line conditions; three used a slot hood; six used inert gas
purging of the vessel, to suppress emissions at the source; two were to evaluate the
closure plate concept; two were launder pours (pouring through the vessel hood); two
were tests of a canopy hood; and the last was an evaluation of slow hot metal pouring.
These tests showed that: a means of minimizing kish carryover will reduce emissions;
slot hoods and gas purging are not practical; systems such as closure plates and
launders, which allow the vessel to remain under the main hood, are effective; and
canopy hoods are effective, if large enough. The study also included: tabulation of
domestic BOP shops; an historical review of BOP steelmaking; the influence of scrap
type on the type and amount of potential emissions; a survey of BOP charging emis-
sion controls in use or which have been tried; and emission tests of a production BOP
vessel during hot metal charging.
7.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
Air Pollution Metal Scrap
Iron and Steel Industry
Steel Making
Basic Converters
Oxygen Blown Converters
Charging
b.IDENTIFIERS/OPEN ENDED TERMS
Air Pollution Control
Stationary Sources
BOP
Hot Metal Charging
COSATl Held/Group
13B
11F
13H
13. DISTRIBUTION STATEMF.NT
Unlimited
19. SECURITY CLASS (Ttiis Rrpon)
Unclassified
21. NO. OF T
166
20. SECURITY CL*\SS (Tliiipa.ec/
Unclassified
22. PDICC
EPA Form 2220-1 (9-73)
157
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