EPA-699/2-76-263
October 1876
Environmental Protection Technology Series
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Research Laboratory
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U.S. DEPARTMENT OF COMMERCE
National Technical Information Service
PB-261 065
Blast Furnace Slips and
Accompanying Emissions as an
Air Pollution Source
BaUelle Columbus Labs, Ohio
Prepared for
Industrial Environmental Research Lcb, Research Triangle Park, N C
Oct 76
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development. U.S. Environmental
Protection Agency, have been grouped into five series. These five broad
categories were established to facilitate further development and application of
environmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The live seric-s are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
This report has been assigned to the ENVIRONMENTAL PROTECTION
TECHNOLOGY series. This series describes research performed to develop and
demonstrate instrumentation, equipment, and methodology to repair or prevent
environmental degradation from point and non-point sources of pollution. This
work provides the new or improved technology required for the control and
treatment of pollution sources to meet environmental quality standards.
EPA REVIEW NOTICE
This report has been reviewed by the U.S. Environmental
Protection Agency, and approved for publication. Approval
does not signify that the contents necessarily reflect the
views and policy of the Agency, nor does mention of trade
names or commercial products constitute endorsement or
recommendation for use.
This document is availab's to the public through the National Technical Informa-
tion Service, Springfield. Virginia 22161.
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57
TECHNICAL REPORT DATA
(flcasc rccd iHisnictiuiii an t!:erc'-cnc in'forc cotr.plclintl
\. REPCRT NO.
EPA-639/2-76-268
TITLE ANQ SUBTITLE
BLAST FURNACE SLIPS AND ACCOMPANYING
EMISSIONS AS AN AIR POLLUTION SOURCE
1. RECIPIENT'S ACCESSION NO.
5. REPORT DATE
October 1976
6. PERFORMING ORGANIZATION CODE
7. AUTHORS;
8. PERFORMING ORGANIZATION REPORT NO.
C.E. Mobley, A.O. Hoffman, and H.W. Lownie
3. PERFORMING ORGANIZATION NAME ANO ADDRESS
Battelle-Columbus Laboratories
505 King Avenue
Columbus, Ohio 43201
10. PROGRAM ELEMENT NO.
1AB604
11. CONTHACT/GRANTNO.'
68-02-1323, Task 60
12. SPONSORING AGtNCY NAME ANO ADDRESS
EPA, Office of Research and Development
Industrial Environmental Research Laboratory
Research Triangle Park, NC 27711
13. TYPE OF RETORT AND PERIOD COVERED
Task Final: 4-7/76
14. SPONSORING AGENCY CODE
EPA-ORD
is. SUPPLEMENTARY NOTES T£RL-RTP Task Officer for this report is R.V. Hendriks, M?fl
Drop 62, 919/549-8411 Ext 2557.
16. ABSTRACT-
The report gives results of a study to ascertain the severity of blast-furnace
slips and their accompanying bleeder-valve emissions as a source of air pollution. It
describes factors contributing to the occurrence of hangs and sljps in the blast furnace.
It discusses the mechanics by which emissions occur from the bleeder valves. It pre-
sents data characterizing blast-furnace bleeder-valve emissions, including the fre-
quency and duration of slip-induced bleeder-valve openings and the quantities of gas
and dust issuing from open bleeder valves,; It concludes that: (1) slip-induced bleeder-
valve emissions are not an industry- or nation-wide problem: (2) these emissions may
constitute an individual furnace and/or local air pollution problem; (3) less total parti-
culates are emitted from this source than from other in-plai t air pollution sources;
and (4) the frequency of bleeder-valve emissions and, in turn, the severity of the pro-
blem have diminished over the last 20 years. The report discusses measures which
may reduce the occurrence and/or severity of blast-.Curnace bleeder-valve emissions.
17.
KEY WOROS ANO DOCUMENT ANALYSIS
DESCRIPTORS
Air Pollution
Iron and Steel Industry
Blast Furnaces
Dust
b.lOENTIFIERS/OPEN ENDED TERMS
Air Pollution Control
Stationary Sources
Blast-Furnace Slips
Blast-Furnace Hangs
Bleeder Valves
Particulate
c. COSATi Field/Group
13B
11F
11G
13. DISTRIBUTION STATEMENT
Unlimited
19. SECURITY CLASS (TMtRtporl)
Unclassified
21. NO. OF PAGES
20. SECURITY CLASS
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
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EPA -600/2-76-268
October 1976
BLAST FURNACE SLIPS
AND ACCOMPANYING EMISSIONS
AS AN AIR POLLUTION SOURCE
•;•••',"•';••• by
C.E. Mobley, A.O. Hoffman, and H.W. Lownie
Battelle-Columbus Laboratories
505 King Avenue
Columbus. Ohio 43201
Contract No. 68-02-1323, Task 60
Program Element No. 1AB604
EPA Task Officer: Robert V. Hendriks
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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ii
ABSTRACT
This study was made to ascertain the severity of blast-furnace
slips and their accompanying bleeder-valve emissions as a source of air
pollution.
Factors concributing to the occurrence of hangs and slips within
the blast furnace are described. The mechanics by which emissions occur
from the bleeder valves are discussed. Data characterizing blast-furnace
bleeder-valve emissions, including the frequency and temporal duration of
slip-induced bleeder-valve openings and the quantity of gas and dust
issuing from opened bleeder valves, ara presented.
. Principal conclusions are:
(1) Slip-induced bleeder-valve emissions
are not an industry-wide or nation-
vide problem.
(2) These emissions may constitute an individual
furnace ar.d/or local air pollution problem.
(3) Less total particulates are emitted
from this source than from other in-plant
air-pollution sources.
(4) The frequency of occurrence of bleeder-
valve emissions, and in turn, the severity
of the problem, has diminished over the
last 20 years.
Measures which may provide a means for reducing the occurrence
and/or severity of blast-furnace bleeder-valve emissions are discussed.
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iii
TABLE OF CONTENTS
ABSTRACT ii
FIGURES iv
TABLES iv
1. SUMMARY AND OVERVIEW 1
II. INTRODUCTION AND BACKGROUND 3
!. Blast-Furnace Off-Gas Systems 6
III. CHARACTERIZATION OF BLAST-FURNACE BLEEDER-VALVE EMISSIONS 10
Frequency of Bleeder-Valve Openings 10
Duration of Slip-Induced Bleeder-Valve Emissions... 17
The Quantity of Gas and Dust Issuing from
Opened Bleeder Valves 18
. IV. EVALUATION OF SLIP-INDUCED BLEEDER-VALVE EMISSIONS
AS A SOURCE OF AIR POLLUTION • 21
V. METHOD AND/OR PROCEDURES FOR REDUCING SLIP-INDUCED
BLEEDER-VALVE EMISSIONS 24
REFERENCES 33
APPENDIX A: .FACTORS CONTRIBUTING TO BLAST-FURNACE
HANGING.
37
APPENDIX B: LETTER RESPONSE OF THE AMERICAN IRON AND
STEEL INSTITUTE (AISI) TECHNICAL COMMITTEE
OK BLAST FURNACE PRACTICE CONCERNING
AVAILABILITY CF DATA ON SLIP-INDUCED
BLEEDER-VALVES EMISSIONS 41
APPENDIX C: SECTION 1810.5: STANDARDS FOR SOURCES - BLAST-
FURNACE SLIPS RULES AND REGULATION;
ARTICLE XVIII, AIR POLLUTION CONTROL
JUNE 15, 1972, ALLEGHENY COUNTY HEALTH
DEPARTMENT 43
APPENDIX D: ALLEGHENY COUNTY HEALTH DEPARTMENT DATA 45
APPENDIX E: ESTIMATE OF QUANTITY Or GAS AND DUST ASSOCIATED
WITH .A BLAST-FURNACE SLIP... 49
APPENDIX F: COPY OF U.S. LETTER PATENT ON "BLEEDER AND
EQUALIZER FOR 3LAST FURNACES" ...... 51
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iv
LIST OF TABLES
Page
Table 1. Summary of Allegheny County Data on Frequency
of Slip-Induced Bleeder-Valve Openings 13
Table 2. Comparison of Several Iron and Steel Plant Air-
Pollution Sources 22
LIST OF FIGURES
Figure 1. Schematic Illustration of a Blast Furnace
and Major Components. 4
Figure 2. Schematic Illustration of Blast Furnace Top 7
Figure 3. Schematic Illustration of Gas Cleaning System 9
Figure 4. Bargraph of Number of Blast Furnaces with
Given Number of Bleeder-Valve Openings/Month 16
Figure 5. Basic System Design for Semi-Clean Gas
Bleeder-Valve Unit 28
Figure 6. Suitable Operating Range for a Blast
Furnace 40
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BLAST-FURNACE SLIPS AND THEIR
ACCOMPANYING EMISSIONS AS A SOURCE OF AIR POLLUTION
I. Summary and Overview
All blast furnaces are subject to operating irregularities,
including hangs and slips. A blast furnace is said to be hanging when
the normal uniform descent of the burden is retarded or interrupted.
Typically, the hanging condition is evidenced by the motion (or lack of
motion) of the burden at the stock line as measured with stock-level rods.
. Hanging is generally attributed to wedging, bridging, or scaffolding of
the burden.
In general, when the burden is not descending at the proper
rate at the stock line, but is continuing to descend in some Icwer section
of the furnace, the probability of slipping increases. Slipping occurs
when the stock moves discontinuously in irregular falls (slips) over
vertical distances of the order of a foot or more at a time. Slips are
evidenced to the furnace operator by surges in the top-gas pressure and
increased top-gas temperatures.
When a heavy or severe slip occurs, as evidenced by a signifi-
cant increase in the top-gas, pressure, one or more pressure-release valves,
known as bleeder valves, manually or automatically open to relieve the
pressure increase. When the bleeder valves are open, either untreated
or partially cleaned blast-furnace gas is released (sometimes flared to
the atmosphere). The untreated gas contains particulates and, therefore,
represents a potential source of air pollution. The objective of this
study is to evaluate blast-furnace slips and their accompanying emissions
as a source of air pollution.
The principal conclusions reached through this study are as
follows:
(1) Slip-induced bleeder-valve emissions are not
an industry-wide or nation-wide problem.
(2) Blast-furnace bleeder-valve emissions nay
constitute an individual furnace and/or
local air-pollution problem.
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(3) Slip-induced bleeder-valve emissions are a
source of less total participates than other
in-plant air-pollution sources.
(4) The frequency of occurrences of bleeder-valve
emissions has diminished over the last 7.0 years.
Based on the data gathered during the study, Battelle researchers
estimate that more, chan 80 percent of the operating furnaces in the U.S.
' ',
(I.e., 100 to 110 blast furnaces) each experience fewer than 5 slip-induced
bleeder-valve emissions per month, and that these do not constitute a major
Source of air pollution. However, then, toay be 15 to 25 blast furnaces for
which the bleeder valves are opened more frequently (i.e., between 20 and 40
times per month) in conjunction with slips.
Battelle researchers estimate that the quantity of dust emitted
from an opened bleeder valve is about 12.5 to 125 kilograms (28 to 276
pounds) per slip. Using the estimated figures for quantity of dust emitted
per slip, it is estimated thai between 170 and. 1671 tonnes (187 to 1842 tons)
of dust were emitted in the U.S. in 1975, from this source. Normalized to
the total hot-metal production of 1975, the emission factor associated with
the slip-induced bleeder openings ranges from about 0.002 to 0.023 kilo-
grams of dust per tonne of hot matal (0.005 to 0.046 pound per net ton).
This emission factor is less than the factor associated with blast-furnace
cast-house emissions and basic oxygen furnace charging and tapping emissions.
The frequency of slip-induced bleeder-valve emissions appeared
to be diminishing during the period 1974 to 1975, and it is known that
the problem has become less frequent over the last 20 years.
Proposed measures which may provide a means for reducing the
occurrence and/or severity of bleeder-valve emissions from problem furnaces
Include:
(1) Improvement of the furnace burden;
(2) Retrofitting of advanced-design gas-processing
systems, such aj the semi-clean gas bleeder-valve
system;
(3) Evaluating the Leone-type differential blowing
system;
(4) Evaluating the performance of blast-furnace
cleaners, such as calcium chloride, as a pre-
ventive measure to reduce the occurrence of
hangs and slips.
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II. Introduction and Background
Fundamentally the blast furnace is a counter-current reactor
in which descending iron oxide, coke, and slag-making materials remove
heat from an ascending stream of hot reducing gases composed mainly of
nitrogen, carbon monoxide, and carbon dioxide. Chemical reduction of
the iron oxide occurs as the charge descends. Finally, there is fusion
of the reduced iron, some unreduced iron oxide, and slag-making materials.
The liquid slag and metal -collect in the hearth of the furnace. Carbon
is burned at the tuyeres to produce heat and carbon monoxide which serves
as the principal reducing agent for the whole process. A schematic
illustration of a blast furnace and associated operations is shown in
Figure 1.
The actual operation of a blast furnace is complicated by
significant deviations from the ideal steady-state uniform reactor im-
plied above. For example, physical inhomogeneities of the charge fre-
quently cause regions of high and low permeability, which in Pirn lead
to nonuniform flow of gas and solids within the furnace. Minor variations
in the flow rates are on an ongoing part of all blast furnace operations,
and, as such, are not generally disruptive to the process. However, all
blast furnaces, including the most modern, are subject to operating ir-
regularities wherein the descent of solids and/or ascent of gases is
sufficiently different from the usual that corrective measures are
required to return the furnace to its normal and controlled mode of
operation.
Common irregularities relating to the nonuniform movement of
materials within the furnace are known as hanging and slipping. A blast
furnace is said to be hanging when the normal uniform descent of the
burden is retarded or interrupted. Typically, the hanging condition is
evidenced by the motion (or lack of motion) of the burden at the stock
line as measured with stock-level rods. Hanging is generally attributed
to wedging, bridging, or scaffolding of the burden. Appendix A, titled
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^m^^M-s *
1. Bler.der valve
2. Gas uptake
3. Small bell
4. Large bell
5. Stock line
6. Stack
7. Bosh
8. Tuyeres
9. Hearth
10. Bustle pipe
11. Slag ladle
12. Hot-metal ladle
13. Dust catcher
14. Downcomer
15. Hot blast line to furnace
16. Gas washer
17. Gas offtake to stove burner
18. Stove
19. Surplus gas line
20. Sto:k—Iron ore, coke, limestone
FIGURE 1. SCHEMATIC ILLUSTRATION OF A BLAST FURNACE
AND MAJOR COMPONENTS
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"Factors Contributing to Blast-Furnace Hanging", (see page 36 ) is in-
cluded for those readers desiring more information on the causes and
contributory factors of blast-furnace hanging.
In general, when che burden is nor. descending at the proper rate
at the stock line, (i.e., the furnace is hanging) but is continuing to
descend in some lower section of the furnace, the probability of slipping
increases. Slipping,is the discontinuous movement of the stock in ir-
regular falls (slips) over vertical distances of the order of a foot or
more at a time. Slips are evidenced to the furnace operator by surges
in the top-gas pressure an-5 increased top-gas temperatures. Operators
frequently attempt to minimize or eliminate uncontrolled slips by "checking";
that is, by lowering the blast volume (the wind rate) whenever hanging is
suspected, or periodically as a part of the normal operating procedure.
The use of checking provides the furnace operator with one method for
controlling the frequency of occurrence and/or the severity of slips.
When a heavy or severe slip occurs, as evidenced by a significant
increase in the top-gas pressure, one or more pressure-release valves,
known as bleeder valves, manually or automatically oper to relieve the
pressure increases. A bleeder valve is shown as Item 1 in Figure 1.
When a bleeder valve is open, blast-furuace gas is released (sometimes
flared) to the atmosphere. The untreated gas contains particulates and,
therefore, represents a potential source of air pollution.
Several references have indicated that slip-induced bleeder-
(1-5)
valve emissions may be a source of air pollution. Little quanti-
tative data have been reported on the frequency of slip-induced bleeder-
valve openings, on the duration of bleeder-valve emissions, or on their
emission characteristics (i.e., dust loading, opacity, etc.). This study
vas undertaken to collect data on slip-induced bleeder-valve emissions,
and, in turn, to evaluate the seriousness of these blast-furnace emissions
as a source of air pollution.
Prior to presenting the data and conclusions generated during
the-study, it is appropriate to describe briefly pertinent volumetric
and transport aspects of the blast-furnace off-gas system. Such
information is presented below.
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Blast-Furnace Off-Gas Systems
To produce a tonr.e of hot metal (molten pig iron) in a blast
furnace, it is necessary to compress about 13<45 m of air. and then to pass
it first through heating equipment (stoves) and then Into the furnace
through the tuyeres. In equivalent English units this converts to about
47,500 SCF*of air per net ton of hot netal. The amount of blast-furnace
gas (top gas) produced is generally about 1.35 times the volume of blast
air. Therefore, the amount of top f,as to be processed is about 1816 m
per tonne of hot metal (about 64,000 SCF per net ton). The pressure drop
across the burden froyi the tuyeres to the space below the burden-charging
system is about 138 kPa (20 psig). Depending on the age of individual
blast furnaces, the top pressure on North American furnaces is controlled
over a range of 13.8 to 103 kPa 2 to 15 psig). Top-gas pressure i;5
controlled by throttle valves (;;eptum valves) or by damper valves associitad
with variable-throat venturi scrubbers. The high-top pressure furnaces
having vaiiable-throat venturi scrubbers are generally the newest (and
largest) furnaces in operation.
The amount of dust blown out of furnaces with top gas varies
amoag individual furnaces. The range is about 10 to 150 kg per tonne
of hot metal (about 20 to 300 pounds per net ton), with the majority
of the North American furnaces being below 25 kg per tonne (below 50
pounds per aet ton). The dust loading in the top gas is then in the
range of 5.5 to 82.6 grams per m3 (2 to 33 grains per SCF). Typically
this gas is cleaned to a dust loading of about 0.011 gram/m (0.005
grain/SCF). At many furnaces, the gas is cleaned to 0.002 gram/m
(0.001 grain/SCF) to further increase the heating performance of the
cleaned gas in the blast-furnace stoves.
Figure 2 is a simplified sketch of the principal operating
parts of the majority of blast-furnace tops in the United States. The
emission sources of interest in this study are the two or more "bleeder
doors" th*Jt are always located at the top of furnaces and are "counter-
weighted to automatically open whenever gas pressure in the top system
SCF » standard cubic feet
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FIGURE 2. SCHEMATIC ILLUSTRATION OF BLAST FURNACE TOP
(6)
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increases suddenly due to slips or other causes". ' The newer high-top-
pressure furnaces have substituted power-actuated valves for the weighted
flapper or "bleeder door" system. In these instances, the top pressure
does not force the valves open. Rather, when the selected pressure trip-
point is reached, powered actuators move the valve downward from its seat
to open the entire cross section of the valve opening. Within the iron-
producing industry, the pressure-release valves and "doors" on the top of
furnaces have many nan::: s. The most common name is "dirty-gas bleeders"
or "dirty-gas bleeders plus the explosion valve". These release systems
are actually safety devices rather than "bleeders".
There is only a limited amount of information on the pressure
settings on the blast-furnace pressure-relief systems. One furnace
operating at 16.5 k.?a (2.4 psig) top pressure has the "dirty-gas bleeders"
set to begin opening at 29.6 kPa (4.3 psig). Blast-furnace builders
have reported that new furnaces operating at 41.3 kPa (6 psig) typically
will have release-valve settings of 55.1 kPa (8 psig) for the first
valve and 58.6 kPa (8.5 psig) for the second valve. As a generalization,
the first bleeder valve is opened at a pressure 2 psig in excess of the
normal top-gas pressure.
Once the dust-laden blast-furnace gas has reached the top of
the furnace, it is ducted to the gas-cleaning system through the down-
comer shown in Figures 1 and 2. The downcomer duct connects to the gas-
cleaning systems, as shown in Figures 1 and 3. All gas-cleaning systems
have a dust catcher as shown at che right side of Figures 1 and 3. Large
particles settle out in this unit, and the fine particles are next
removed by subsequent combinations of scrubbers or scrubbers and electro-
static precipitators.
As part of the development of high-top-pressure blast-furnace
operations, a system was devised for partially relieving the slip-
induced excess pressure by venting partially cleaned gas through a
bleeder valve located downstream from the dust catcher. * The
incorporation of a semi-clean-gas bleeder valve to exhaust partially
cleaned gas at the top of the furnace should provide a method and/or
apparatus for lowering, the quantity of dust emitted from slip-induced
bleeder-valve openings. While some U.S. blast furnaces are kno-m to be
equipped with and to utilize semi-clean-gas bleeder valves to partially
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CB1Y CAS
MftSUOCriATt
VMVt
CUAMCAi
FIGURE 3. SCHEMATIC ILLUSTRATION OF
GAS CLEANING SYSTEM (7)
relieve the pressure pulses associated with furnace slips, the number
of furnaces using such systems is not known. The utilization of the
semi-clean-was bleeder valves as a means to reduce the slip-induced
bleeder-valve emission problem if.' discussed in Section V of this report.
III. Characterization of Blast-Furnace Bleeder-Valve Emissions
While previous studies and articles 'had indicated that
blast-furnace bleeder-valve emissions due to slips were a potential
source of air pollution, few quantitative data were available to
assess the extent of this potential problem. The basic data which
were lacking for such an evaluation included:
(1) The frequency of slip-induced bleeder-valve openings,
(2) The temporal duration of the bleeder-valve openings,
(3) The gas-flow rate issuing from the open bleeder-valves,
(4) The dust-loading factor for the bleeder-valve emission.
An evaluation of each of these factors is presented below.
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10
Frequency of. Bleeder-Valve Openings
Blast-furnace bleeder valves remain closed practically all
of the time that the furnace is in blast (i.e., is in normal operation).
However, the bleeder valves are opened in response to or as part of
several blast-furnace operating conditions. For example, the bleeder
valyes may be opened intentionally as part of the furnace shutdown
practices or during backdrafting. The valves may also be opened
intentionally during periods of maintenance and repair to the furnace
proper, such as during replacement of tuyeres or monkeys. The bleeder
valves are also opened during periods of repair to the gas-cleaning
system. As previously stated, bleeder valves are also utilized as the
safety relief valves for the release of the excess pressure associated
with slips.
Blast-furnace bleeder valves are typically opened intentionally
more frequently for maintenance and repair purposes than as a result
of slips. For example, based on data collected by the Allegheny County
(9)
Health Department, Pittsburgh, Pennsylvania, . the bleeder valves on
two blast furnaces were opened a total of 52 times over a 2-week period
in 1975. Of these 52 bleeder-valve openings, 49 were intentional for
reasons of furnace maintenance and repair, and 3 (i.e., about 6 percent
of the total) were caused by slips.
Only those bleeder-valve openings due to slips are considered
significant as an air-pollution source. The gas emission rates and dust-
loading factors for the emissions from open bleeder valves in conjunction
with furnace maintenance and repairs are thought to be relatively small.
Generally the wind on the furnace is significantly reduced from the
nomal operating valves during the periods of maintenance and repair.
The quantity of top gas, and the dust loading of the top gas, are con-
sidered negligible during maintenance and repair periods relative to
periods of normal and full production operation. Also, frequently, steam
is introduced into the furnace for gas purging purposes, and it is the
* Backdrifting refers to the condition when the furnaces gases are drawn
through the tuyeres to a hot stove where the gas is burnt. Thus, the
gas flo.* in backdrafting is reversed from that for normal furnace
operatiou
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11
steam, rcther than dust-laden gas, which is vented from the opened
bleeder valves during these periods of reoair. Thus, the data which
were sought as input for this study are the t.hp number of slip-induced
bleeder-valve openings per unit of time. It should be recognized that
this may not be the same as the number oC slips experienced during
a given operating period. Only those slips which generate an excess
pressure equal to or greater than that required to ypen the bleeder
valves are of interest at, sources of air pollution.
Most, if not all, blast furnace operations continuously record
the furnace top-gas pressure on 24-hour recording charts as part of
their collection of operating data. By analyzing the top-pressure
records (plus considerati ..3 of the other recorded operating data),
Che number of slips occurring during any operating period can be
determined. Although these dat (i.e., total number of slips and number
of slips producing open bleeder valves) are a part of the continuously
recorded operating data, few companies routinely analyze their records
Co determine and/or report this information.
As part of this study, the researchers contacted the American
Iron and Steel Institute (AISI) requesting slip and bleeder-valve
opening-frequency data from the U.S. steelmaking industry. Consistent
with Che responses from individual companies contacted by the research
team, the AISI Technical Committee on Blast Furnace Practice indicated
ChaC the requested information (i.e., total number of slips and slip-
induced bleeder-valve openings per unit time) was not generally
recorded and available. The lettar response of the AISI Technical
Committee on Blast Furnace Practice Co our inquiry on the availability
of slip frequency and bleeder-valve data is presented in Appendix B.
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12
Data collected by Battelle for an earlier Government report
on the causes of air pollution from the; integrated iron and steel
industry had indicated that for some blast furnaces the bleeder
valves are rarely open as a result of slips. One plant containing
ight"furnaces had reported in 1968 that one or two short-interval
openings of the bleeders occur during any given week for the total of
all eight furnaces. These data are equivalent to a frequency
statement of 1/2 to 1 slip-induced bleeder-valve opening per furnace
per month.
During this study, Battelle researchers contacted two com-
panies which operate blast furnaces to ascertain the frequency of.
slip-induced bleedar-valve emissions for their operations. Both
companies indicated that bleeder valves are open far more frequently
for furnace maintenance purposes than as a result of slips. Both
companies also estimated that their bleeder valves were opened
several times per month (i.e., 3 to 8) for each blast furnace in
response to slips.
On contacting several regional EPA offices and local
air-pollution control groups, it was learned that the Allegheny
County Health Department, Pittsburgh, Pennsylvania, included consideration
of allowable emissions.resulting from blast-furnace, slips in its
June 15, 1972, Rules and Regulations, Article XVIII, Air Pollution
Control. As set forth in that document, blast-furnace bleeder
valves are not allowed to emit, as a result of a slip, more than
60 times in any consecutive 12-month period, or more than 10 times in
any consecutive 30-day period. Section 1810.5 of the Allegheny County
Health Department Rule., and Regulations dealing with emissions
associated with blast-furnace slips is presented in Appendix C.
As stipulated in the rules and regulations concerning
emissions due to blast-furnace slips, the Allegheny County Bureau of
Air Pollution Control has, since 1972, collected data on the monthly
number of slip-induced bleeder-valve openings for blast furnaces
within Allegheny County. Typically, there were 13 to 17 blast
furnaces in blast in Allegheny County each month during the period
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13
1972 through 1975. These Allegheny County data on blast-furnace
slip-induced bleeder-valve openings per month over the 4-year period
1972 through 1975, for 16 different blast furnaces at five plant sites,
are presented in Appendix D.
A sucaary of the Allegheny County data in Table 1 includes
the total number of slip-induced bleeder-valve openings reported, the
product'.of the number of blast furnaces and the number of months each
year for which data were reported" and, in turn, the yearly average
number of bleeder-valve openings per blast furnace-month for ei.:h
year from 1972 through 1975.
TABLE 1: SUMMARY OF ALLEGHENY COUNTY DATA ON FREQUENCY OF
SLIP-INDUCED BLEEDER-VALVE OPENINGS •'
Year
1972
1973
1974
1975
Total Number of
S.'.ip-Induced
Bleeder-Valve
Openings Reported
1U4
1128
1373
324
Blast Furnace-
Months
138
124
144
84
Avg. Number of
Bleeder-Valve
Openings Per
Blast Furnace Month
8.3
9.1
9.5
3.9
The Allegheny County Health Department data summarized in
Table 1 indicate that there were typically an average of 8 to 10
slip-induced bleeder-valve openings per furnace each nonth during the
period 1972 through 1974. In 1975, the aver-ige number of monthly
slip-induced bleeder-valve openings decreased to about 4 per furnace.
The reduction in the average number of slip-Induced bleeder-valve
openings par aonth evidenced in 1J75 appears to be largely the result
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14
of discontinuing operations of several blast furnaces which had
previously experienced significantly more bleeder-valve openings
than the averages.
The data in Table 1 are averages based on the accumulated
data from 16 blast furnaces reporting during each of the given
years. These average values do not provide insight to the frequency
of occurrence of any particular value (i.e., the distribution of values).
On examining the individual furnace data presented in Appendix D, it is
noted that few furnaces exhibit open bleeder-valve frequencies comparable
to the average values.given in Table 1. Based on the Allegheny County
data, the blast furnaces can be grouped into essentially two categories,
i.e., those which seldom experience slip-induced bleeder-valve openings
and those for which the frequency of opened bleeder valves is consist-
ently in excess of 15 times per month. For example, for the 15 blast
furnaces reporting bleeder-valve opening data in 1974, 9 furnaces
(i.e., 60 percent of the total) had yearly averages of less than
2 bleeder-valve openings ptr month, 2 furnaces (i.e., 13 percent) had
between 2 and 5 bleeder-valve openings per month, while 4 furnaces
(27 percent) reported yearly average bleeder-valve openings in
excess of 15 per month (i.e., Blast Furnace 6 at Plant B had 16.1
openings/month, Blast Furnace 7 at Plant A had 21.7 openings/month,
Blast Furnace 3 at Plant B had 20.1 openings/mo .'. i and Blast Furnace
5 at Plant B had 49.2 openings/month).
A representative of the Allegheny County Bureau of Air
Pollution Control indicated that they also monitor three blast furnaces
in Allegheny County for which open bleeder-valve frequency data are
• not included in Appendix D. For those 3 blast furnaces (not included
in Appendix D), the yearly average number of slip-induced bleeder-
valve openings was estimated to be less than 5 per month.
At the start of this study, Battelle researchers were aware that
the City of Cleveland, Ohio, Division of Air Pollution Control was
actively attempting to obtain and evaluate blast-furnace bleeder-
valve emission data.' As part of this study, representatives of th
Cleveland Air Pollution Group were contacted to obtain bleeder-valve
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15
opening data. Cleveland has not monitored end/or collected blast-
furnace bleeder-valve opening data of a similar nature to the Allegheny
County data for the blast furnaces within the Cleveland city boundaries.
However, a representative of the Cleveland Air pollution Control'
Division indicated that bleeder-valve emissions are considered to be a
problem with only one of the seven blast furnaces currently operating
in that area. For six of the seven blast furnaces operating in Cleveland,
it was estimated that the bleeder valves seldom opened more than 4 to 5
times per month due to furnace slips. For the one blast furnace, it
was estimated that the bleeder valves were opened between 30 and 40
times a month as a result of slips.
These measured and estimated bleeder-valve opening data are
combined and presented in Figure 4 to show the number of blast furnaces
which experience bleeder-valve openings a specified number of times
each month. While the data presented in Figure 4 are for different
years (see the legend on the figure), each data entry is for an
individual furnace. It is thought that the bleeder-valve opening
frequencies have not changed significantly with time for those
particular furnaces for which data arc included.
The 32 furnaces considered in Figure 4 represent about 1/4
of the total number of U.S. operating blast furnaces as of early 1975.
Of these 32 blast furnaces, 27 (i.e., about 77 percent of the total)
had less than 6 slip-induced bleeder valve openings per month as a
yearly average value. Five blast furnaces (i.e., about 23 percent of the
total) had more than 16 slip-induced bleeder valve openings per month
as yearly average values. The average number of bleeder-valve openings
per month for those five furnaces was about 30 per month.
The data presented herein should not be taken as a basis from
which a precise single-valued national value for slip-induced bleeder-
valve opening per furnace per month can be derived. As previously
stated, the data in Figure 4 are for several different years and for
* Of a total of 197 furnaces there were 135 blast furnaces in blast in
the U.S. as of January, 1975. As of January 1, 1976, the number of
active furnaces had decreased to 119.
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30
4 -»6 10 16-»-18 20*22 26-»-28 30 34+36 ?0 48+50
Average Number of Slip-Induced Bleeder-Valve Openings/Month
FIGURE 4. BARGXAPH OF KUMBER OF BLAST FURNACES WITH GIVEN NUMBER OF
BLEEDER-VALVE OPENINGS/MONTH
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17
different practices. The data represent about 25 percent of the total
number of active blast furnaces in the United States. However, based
on these data and on the general impression arrived at through inter-
views and discussions with plant personnel and environmental control
groups, we believe that the general industry-wide situation is comparable
to the trends indicated in Figure 4. That is, we estimate that, for
more than 80 percent of the operating blast furnaces (i.e., for about
100 to 110 blast furnaces), the bleeder valves are opened only a faw
times per month as the.result of furnace slips. However, for each of
15 to 25 furnaces in the U.S., the bleeder valves may be opened in
conjunction with slips between 20 and 40 times per month on an annual
average basis.
Battelle researchers attempted to gather information and
data about the causes of the higher frequency of slip-induced bleeder-
valve emissions for th-3 five "problem" furnaces identified in
Allegheny County and Cleveland. No single factor or combination of
factors was found to correlate with the greater occurrence, of bleeder-
valve openings in these furnaces than in any others. The five furnaces
all had hearth diameters of less than 26 feet. However, this fact
alone is an inadequate explanation as to the cause of frequent bleeder-
valve emissions, because there are many other 26-foot and smaller
blast furnaces in operation for which bleeder-valve emissions are
not a reported problem.
Duration of Slip-Induced Bleeder-Valve Emissions
Blast-furnace bleeder valves are open for the time period
that the furnace top pressure due to the slip exceeds the pressure
required to open the bleeder valves. The duration of the pressure pulse
associated with slips typically is from several seconds up to about
30 seconds. All the blast-furnace operators and representatives of
various environmental control groups questioned during this study
indicated that bleeder valves are seldom open more than 30 seconds in
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18
response to a furnace slip. Emission times of 30 seconds or less are
also consistent with measurements made by Battelle investigators while
observing ten operating blase furnaces for several days.
In some cases, there may be an additional 30-secotid emission
period following the slip-induced bleeder-valve emission. This is
associated with the operator-imposed opening and closing of the valves
in an effort to seat and reseal the bleeder-vslve unit.
In keeping with the above discussion, the temporal duration
of slip-induced bleeder-valve emissions is taken to be 30 to 60 seconds.
It should, however, be recognized that these times are probably longer
than most emission times associated with slip-induced bleeder-valve
openings.
The Quantity of Gas and Dust Issuing From Opened Bleeder Valves
Little or no measured data are available relating the quantity
or flow rate of gas issuing from an opened bleeder valve- The quantity
of dust emitted and the dust-loading factor are also unknown.
Gas-flow rates and dust-loading factors are known character-
istics for most blast furnaces which are operating in the normal con-
trolled condition. However, during periods of furnace irregularities
(such as during slips) it ii thought that the gas-flow rate and dust
loading differ from these normal steady-state values.
Because no data relating gas and dust quantities emitted in
conjunction with blast-furnace slips were found, it was considered
desirable to develop a calculated estimate for these variables.
Estimates of the quantity of gas and dust emitted from slip-induced
bleeder-valve openings are developed in Appendix E. Based on the model
and assumed conditions presented in Appendix E, it is estimated that
about 18.2in (650 SCF) of gas are generated during a 0.61 meter
(2 foot) slip in a 9.1-meter (30-foot) blast furnace. Assuming that
the dust loading during the slip is 10 to 100 times greater than the
maximum normal dust loading implies that between 12.5 and 125 kilograms
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(28 to 276 pounds) of dust are contained in the emitted gas. Thus,
if the entire volume of emitted gas were released from the dirty-gas
bleeder valves, an estimated quantity of dust in the range of 23 to
275 pounds would be emitte.J. for a "2-foot:" slip in a 30-foot-diameter
furnace.
These estimated quantities cf dust associated with a slip
are considered conservative (i.e., it is doubted that the actual
qualities of dust released exceed these estimates). For example, a
1 ': ' •
2-foot-high cavity, would seldom, if ever, exist across the entire
dianeter of the furnace. Other input data used to develop these values
(such as cavity gas temperature and pressure) are believed to be
realistic estimates of the accual conditions associated with the slips.
The gas-volume and dust-quantity estimates presented here
are offered as a means of arriving at an order-of-magnitude value
for the quantity of dust emitted from a dirty-gas bleeder valve due to
slips. To the best of our knowledge, no data exist to confirm or
refute the estimate presented.
Little or no data are available on the composition and size
distribution of the particulates emitted from the slip-opened bleeder
valve. Certainly, the expected compositions of the particulates are
those of the burden charged to the furnace (i.e., iron oxide, coke,
and limestone). No estimate of the size distribution of the djst is
presented here, because these data are not believed to constitute
a primary factor in judging the significance and/or severity of the
emissions from the slip-opened bleeder valves.
The gas emitted from the bleeder valves is expected to be
of a compo.sition comparable to ihe normal furnace offgas mixture
(i.e., about 25 percent carbon monoxide, 15 percent carbon dioxide,
4 percent hydrogen, balance nitrogen). Because of the carbon monoxide
content, the venting of the gas is performed at the top of the furnace
and/or the gas is flared.
The data presented in this section can be used to formulate
a quantitive assessment of the severity of bleeder-valve emissions as
a national and local air-pollution problem. Such an assessment is
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20
developed in the following section of this report. However, the
results of the computations are heavily dependent upon the assumptions
that have been aade.
IV. Evaluation of Slip-Induced Bleeder-Valve
Emissions as a Source of Air Pollution
Based on the data presented in the preceding sections of this
report and supplemental data provided herein, the seriousness of blast-
furnace bleeder-valve emissions resulting from slips can be estimated.
The following statements and supporting discussion summarizes Oattelle's
evaluation of blast-furnace bleeder-valve emissions as a source of air
pollution.
# SUp-Iuducec. 31ast-Furnace Bleeder-Valve
Emissions Are Not An Industry-Wide or Nation-
wide Problem.
As depicted in Figure 4, bleeder-valve openings due to slips
are a relatively infrequent occurrence for the majority of blast fur-
naces operating in the U.S. For the 32 blast furnaces (about I/A of
the total number of U.S. furnaces as of early 19'."5) for which bjeeder-
valve opening data were collected, about 75 to 80 percent of the furnaces
*
experienced fewer than 6 emissions per month . These data are consistent
with and reinforced by the responses of many representatives of both
iron and steel companies and regional air-pollution control groups to
the effect that blast-furnace bleeder-valve emissions occur infrequently
and are of only minor concern as a source of air pollution at most
individual plants and/or in given geographic regions of the U.S. Repre-
sentatives of regional EPA offices in Region A (Atlanta, Georgia) and
Region 3 (Philadelphia, Pennsylvania), and representatives of local
air-pollution control groups in California and Maryland indicated that
blast-furnace bleeder-valve emissions were not considered by them as a
significant source of air pollution within their regions of jurisdiction.
* Nearly 50 percent of the furnaces experienced fewer than two slip-
induced bleeder-valve emissions per month.
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21
• Blast-Furnace Bleeder-Valve Emissions May Constitute
• an Individual Furnace And/Or Local Air-Pollution Problem
Data from the Allegheny County Health Department and from the
City of Cleveland indicate that there are individual blast furnaces
which experience bleeder-valve emissions with sufficient frequency to
warrant concern. Based on the data in Figure 4, 5 of the 32 furnaces
.for which data were available had between 20 and 50 (an average -alue of
30) bleeder-valve emissions per month. Accepting the 16 percent figure
(i.e., 5 of 32) as representative of the total U.S. ironmaking industry
would imply that there were about 22 "problem" blast furnaces in early
1975. Assuming that each of these 22 furnaces experienced 30 slip-induced
bleeder-valve emissions per month with an emission of 30 to 275 pounds
of dust, for each slip would result in an average annual dust emission
of about 5 to 50 tons (4.5 to 45 tonnes) per year per furnace. The total
annual dust emission from all 22 blast furnaces would be from 110 to 1100
tons (99 to 990 tonnes).
Assuming that the remaining 113 blast furnaces operating in
the U.S. in 1974-1975 (for a total number of. 135 furnaces) averaged four
slip-induced bleeder-valve emissions oer month indicates that there
was a total of about 13,350 slip-induced bleeder^valve emissions in the
U.S. in 1974. The 22 furnaces (i.e., 16 percent of the furnaces) with
the higher emission frequency account for nearly 60 percent of this
total.
In considering the probable geographic distribution of the
estimated 22 frequently emitting blast furnaces, it is considered likely
that no more than four to five such probleta blast furnaces are operating
in a given local community.
• Slip-Induced Bleeder-Valve Emissions Are A Smaller Air-
Pollution Source Than Are Other Iron and Steel Plant
Operations
Based on the data presented in the previous section, the total
number of slip-induced bleeder-valve emissions in the U.S. in 1974
is estimated as about 13,350. For a dust loading of 28 to 276 pounds
per slip, the quantity of dust generated for the U.S. in 1974 from
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22
(12)
this source was between 187 and 1842 to.is (170 and 1671 tonnes). In
1975, the U.S. iron makers produced 79.9 million nat tons of hot metal.
Thus, the quantity of dust generated in blast-furnace bleeder-valve
emissions resulting from slips normalized to the blast-furnace production
*
ranges from about 0.005 to 0.046 pound of dust per net ton of hot metal .
In comparison, the estimated emission factors (i.e., pounds of dust emitted
per ton of product) associated with the blast-furnace cast-house opera-
tion range from about 0.12 to 0.61 pound of dust per net ton of hoc zetal.
Combining the cast-house emission factor with the 79.9 million net ton
of hot metal produced in 1975 indicates that between 4790 and 24,370 tons
' • .' • **
of cast-house dust were generated in the U.S. in 1975
Another basis for comparison is associated with the charging and
tapping of the basic;pxygen furnace (EOF). Based on an article by Mattis ,
an estimated emission of between 2.3 and 13.8 pounds of dust per ton of
steel is associated with the charging and tapping emissions of the BOF.
Because 71.8 million tons of BOF steel were produced in the U.S. in 1975,
the total quantity of dust generated from this source is estimated to be
between 82,600 and 495,400 net tons.
These comparisons are given in Table 2.
TABLE 2. COMPARISON OF SEVERAL IRON AND STEEL
PLANT AIR-POLLUTION SOURCES
Emission
Sources
Estimated Emission
Factor (pounds per
ton of product)
1975 U.S. Estimated Annual
Production Total Dust Emis-
(mlllion tons) sion (net tons)
Blast-furnace
bleeder valves
Blast-furnace
cast house
BOF
Charging and tapping
0.005 - 0.046
0.12 - 0.61
2.3 - 13.8
79.9 187 - 1842
79.9 4790 - 24,370
71.8 82,600 - 495,400
* The U.S. 1974 hot-metal production was 95.9 million net tons. Using this
production figure implies emission factors between 0.004 and 0.038 pound
of dust per net ton of hot metal.
** EPA is currently funding a study to assess the blast-furnace cast-house
emission problem.
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23
The blast-furnace bleeder-valve emission factors pre-
sented in Table 2 are baaed on the total 1975 U. S. production
of hot metal. Bleeder-valve emission factors for individual
blast furnaces can be derived frou knowledge of the individual
furnaces' bleeder-valve emission frequency and the furnaces'
productivity. Thus, for example, a blast furnace which produced
1300 tons of hot metal per day and experienced A slip-induced
bleeder-valve emissions per month would have an estimated
bleeder-valve emission factor in the range of 0.003 to 0.023
pounds of dust per ton of hot metal. If this 1300 ton per day
furnace experienced 30 slips per month (i.e., was a "problem"
furnace), then the estimated bleeder-valve emission factor for
that furnace would range from 0.022 to 0.212 pounds of dust per
ton of hot metal. It should be noted that the bleeder-valve
emissions factor associated with a furnace having a relatively
high frequency of slip-induced bleeder-valve emission(e.g., 30
bleeder emissions per month) is comparable co the estimated
emission factors for the blast-furnace cast house. Thus, the
developed emission factors support the premise that blast-
furnace bleeder-vilve emissions may constitute an individual
and/or local air pollution problem.
The slip-induced bleeder-valve emissions based on national
production figures appear to be small relative to the emissions of
other in-plant air-pollution sources. Based on these data, and
the responses from representatives of several air-pollution control
groups, the bleeder-valve emission problem appears to be of
• i '
secondary concern on a national basis, relative to other potential
air-pollution sources. However, this source of air pollution may
constitute a local air pollutent comparable to other known sources.
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24
• The Frequency of Occurrence of BlasC-Furnace Slip-
Induced Bleeder-Valve Emissions Has Diminished
Over the Last 20 Years
Many of the blast furnace operators interviewed during
this study indicated that the frequency of occurrence of slips
.and bleeder-valve openings is significantly less today than 20
years ago. While slip-induced bleeder-valve openings data are
^difficult to obtain for blast-furnace operations of years ago, it
appears that the frequency of slips has diminished because burden
quality and preparation have improved. This is supported by the
observation that slip frequency used to be reported in the frame-
(2)
work of several tens of slips per day , whereas today's fre-
quencies are generally on a scale of several to tens of slips per
month.
While the trend of decreasing frequency remains to be
confirmed with 1976 and future data, the Allegheny County Health
Department Data presented in Table 1 reflects a reduction in
bleeder-valve emissions resulting from slips from 1974 to 1975.
As blast-furnace operations are continuously updated in terms of
improved burdens and operating practices and equipment, the fre-
quency of slip-opened bleeder-valve emissions is expected to lessen
until only a few blast furnaces operate with more than several
bleeder-valve emissions per month.
V. Method and/or Procedures for Reducing
Slip-Induced Bleeder-Valve Emissions
Given that a particular blast furnace consistently experi-
ences a significantly higher frequency of bleeder-valve emissions
than other blast furnaces, some of the choices that may be avail-
able to improve the situation are (1) improvement in the physical
and chemical characteristics of the burden material charged to
this furnace and (2) equipment
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25
modifications Co cope with the pressure surges without releasing particu-
lates to the atnosphere. Coping with the slip pressure surge involves
taking corrective or anticipatory actions to minimize the pressure rise,
or using systems which.are capable of containing the surge within the
gas-processing system.
The burdening of blast furnaces is (1) a complex subject,
(2) an area where dramatic improvements have been made in the recent
past, and (3) the subject of continuing intensive study. Before blast-
furnace burdens were upgraded to gain improved furnace performance,
emissions from the bleeder valves were frequent and part of the normal
operation. With improvement in burdening (and other operational consider-
ations) , blast-furnace operations have become less erratic and bleeder-
valve openings are now a less frequent occurrence.
The improvement of blastrfurnace burdens is an ongoing
endeavor with most iron makers, it is expected that future improve-
ments will lower the frequency of bleeder-valve-opening emissions on all
furnaces. The iron and steel companies are well aware of the inter-
relation between burden improvements, improved operations, lower overall
costs, and reduced irregularities. However, implementation of improve-
ments can be difficult and slow. As one example of technical difficulties,
it should be noted that in the last several years blast-furnace operators
have reported that the quality of coke, and particularly the variability
in the quality of coke (strength, ash content, etc.), has been causing
operational problems in blast furnaces. This is a second-order result
of the problem;) and marketing upsets that have occurred in the U.::.. coal
Industry. The increased demand for low-sulfur coal, the lower produc-
tivity in coal mines, and the decreased attention to grading and cleaning
of coals during peak demand periods have contributed to the problem of-
variable-quality coke. This problem has negatively affected blast-furnace
performance worldwide. The problem, and the search for a solution, is
continuing. The fact that the problem is continuing is evidenced by the
panel discussion devoted to the subject at the March, 1976, Ironmaking
Conference in St. Louis, Missouri. Given the effort that is being
expended to regain control over coke quality and consistency, it is to
be expected that in the future a recovery will be accomplished, overall
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26
improvement in the blast-furnace burdening will be resumed, and future
irregularities will be decreased.
The high frequency .of bleeder-valve openings on a few furnaces
is of concern to some regional or local air-pollution control authorities.
Because of the complexity of the subject of burdening of individual
furnaces, BatteLle researchers have no specific recommendations in this
regard. Discussions with officials of steel companies that have problem
blast furnaces indicate that the frequency of bleeder-valve openings is
being decreased. However, these officials did not feel that they were
in a position to discuss individual furnace burdening or coke quality.
Thus, Battelle researchers do not know in detail the means by which the
performance of particular individual furnaces is being improved. The
fact that performance is being improved is encouraging, and it is believed
that the operating improvements may result mostly from improved burdening
of these furnaces.
It is Important to realize that the quality of burden being
charged to individual furnaces today is frequently 'he result of
decisions made years earlier. It is a generalization that, as the
general level of blast-furnace burden quality ^r.d consistency is increased
within a steel company, the best and most consistent quality burden is most
often charged to their newest and largest blast furnace. With time,
continued improvements in burden quality are passed on to the older and
generally smaller furnaces. This, in part, may account for the observa-
tion that the blast furnaces presently experiencing a higher frequency
of slip-induced bleeder-valve openings per month are, relatively speaking,
smaller furnaces.
Burden-improvement considerations aside, it is the judgement
of Battell a researchers that changes and improvements might be made in
blast-furnace equipment and procedures to decrease the frequency of
bleeder-valve openings. These suggestions are discussed in the follow-
ing text, and should be considered in the event that the frequency of
bleeder-valve openings cannot be brought below regulatory limits by means
of burden and/or practice improvements. Blast-furnace operators are in
agreement that each blast furnace has individual characteristics. This is
another form of the statement that "not all that needs to be known about
blast-furnace operations is known". Assuming that the frequency of
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27
bleeder-valve openings is not brought under control at a particular
blast furnace, ;he following suggestions are offered for consideration.
1. Evaluate the Possibility of Increasing the Pressure-Release Setting
on the Bleeder
When asked what he did to prevent frequent popping-off of the
bleeder valves, one blast-furnace superintendent stated that he:
: • Increased the weight on his dirty-gas bleeders so that
they would open only ar. a higher pressure,
• Began using in the charge more "cleaners" of both
:" . mechanical and chemical types, and
.."-.-. • Went into earlier checking practice when hanging was
indicated.
In this instance, the structural strength of the blast furnace
(and the gas-processing system) structure were analyzed. It was found
that the pressure-release setting at the dirty-gas bleeders could be
increased without rupturing the furnace or the gas-processing system
during a slip. In effect, many of the pressure surges occurring in the
furnace were contained. That is, the increase in pressure was drawn off
through the gas-processing system without opening the dirty-gas bleeders
This rather simple alteration may not be possible at many of the older
furnaces. The subjects of checking (periodic lowering of the wind rate
on a furnace) and the use of cleaners are discussed in the following test.
2. Consider Retrofitting Advance-Design, Gas-Processing Systems to
Existing Furnaces
In 1952, K. G. Le Viseur, et al., was awarded a U.S. letter
patent, assigned to Republic St»:el Corporation, entitled "Bleeder and
(4)
Equalizer For Blast Furnaces". Figure 5 is the main drawing given in
this patent. A copy of the Le Viseur patent is included in this report
as Appendix F. This patent is "particularly concerned with apparatus by
which clean gases may be used to equalize the pressure on opposite sides
of the chaigi-.j bell and may also be vented to the atmosphere instead of
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28
FIGURE 5: BASIC SYSTEM DESIGN FOR SEMI-CLEAN GAS
BLEEDER-VALVE UNIT (4>
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29
dirty gas whenever slips and rolls of the furnace occur which are of minor
or moderate intensity". Referring to Figure 5, Le Viaeur proposed installing
a duct downstream of the first gas-cleaning unit to the top of the furnace
for venting gas-pressi; -e increases. The system consists of Items 21, 22,
27, and 28 in the drawing. Quoting from the patent, "where delivery gas
is vented to the atmosphere either from the hopper chamber or from the
furnace by reason of slips and rolls, much dirt is discharged and consti-
tutes a nuisance to adjacent buildings and residences. Among the numerous
advantages of this venting only clean gas is the fact that bleeder-valve
erosion, which is especially serious in furnaces operating at high top
pressure, is substantially reduced. Sudden moderate increases in gas
pressure in the furnace caused by slips and rolls nay be relieved this
way and the gas allowed to escape through valve 22 is clean, coming
(A)
as it does from the washer and hence is not a public nuisance".
In this report, we refer ro this type of system as the seat-
clean bleeder system because the dust content in the gas released from
downstream of the first gas-cleaning ur.it may still be about 0.09 gram
per cubic meter (about 0.04 grain per cubic foot).
The semi-clean bleeder system was installed on some furnaces
built in the 1960's and 70's. Furnaces equipped with the semi-cleah-gas
bleeder system use the dirty-gas bleeders only as relief valves for
handling heavy slips. In theory, the semi-clean-gas bleeder system co.uld
be retrofitted to older furnaces. Each furnace, however, would have to
be individually examined. For example, in order for the semi-clean-gas
bleeder to be effective, the pressure surge must be passed rapidly
through the first cleaner. If the first scrubber appreciably resists
the gas flow, the dirty-gas bleeder will sense the slip-induced pressure
pulse and open before the semi-clean-gas bleeder has received a signal.
In some instances, it may be advantageous to replace the existing scrubber
with a fast-response, variable-throat, pressure-controlling scrubber.
In attempting to judge whether this semi-clean bleeder system could be
retrofitted to older furnaces, a brief study was made of the progress
being made in gas-cleaning and gas-pressure-control systems. Discussions
were held with builders and suppliers of equipment to blast-furnace
-------
30
engineering companies. Representatives of one company (Air Pollution
Industries of Englewood, N.J.) indicated that fast-response, variable-
throat venturi scrubbers have been developed for cleaning blast-furnace
gas for low-top-pressure furnaces. In this instance, the throat damper
in the scrubber is made to open rapidly with increases in top pressure in
order to pass more gas through the scrubber system. This pressure pulse
can be totally contained within the remainder of the gas-cleaning system^
or may be vented through a retrofitted semi-c.lean-gas bleeder. Variable-?
throat, pressure-controlling scrubbers have been retrofitted to older
blast furnaces. However, to the best knowledge of Battelle researchers,
these retrofit scrubbers did not include a rapid-response pressure-control
system. Based on the available information, Battelle researchers judge
that the modification of the gas-handling systems on old furnaces to the
designs used on new blast furnaces would reduce the frequency of opening
of the dirty-gas bleeder valves on a problem furnace. However, blast-
furnace operators and design engineers within steel companies questioned
the actual workability of the proposed retrofit 'considerations. Thest
discussions, however, were limited In nature. Should this topic become
one of need, i.e., for a blast furnace whose frequency of bleeder-valve
openings cannot be brought under control, it is suggested that the work-
ability of the approach could be evaluated in a demonstration project by
I
adding the fast-response feature to an existing pressure-controlling,
variable-throat scrubber system that has been recently retrofitted to a
low-top-pressure blast furnace.
3. Consider the Leone System as a Method for Reducing the Occurrence
of Hangs and Slips
Several references ' ' have indicated that the frequency
of occurrence of hangs and slips (including slip-induced bleeder-valve
openings) can be markedly reduced by using a system known as the Leone
Differential Pressure Control System for sensing and controlling the
movement of materials in the blast furnace. The Leone system is based
upon measuring and controlling the differential pressure drops across the
burden of tt.e furnace. Such a method or system may have potential for
-------
31
reducing the emissions from a blast furnace which has consistently evi-
denced a high frequency of slip-induced bleeder-valve openings.
For example, the Leone system was evaluated in 1950-1951 on a
blast furnace which had experienced numerous hangs and slips prior to the
(14)
use of the differential control system. The furnace (normally rated
at about 560 to 700 tons of hot metal per day) had experienced an average
of 33 slip-induced bleeder-valve openings per month for the 6-month period
prior to usage of the control system. The slip-induced bleeder-valve
opening frequency dropped to an average of 9 per month for the 6-month
period after the differential pressure system was put into operation,
with no reduction in furnace production.
'(14)
•:'. Leone and Adams claim that the Leone type system will:
(1) Reduce the number of dirty-gas bleeder-valve openings,
(2) Decrease the frequency of hangs and slips, and
(3) To a limited extent, increase furnace production.
These claims are all positive in terms of improved furnace
performance. Discussions with Mr. Leone, blast-furnace builders, and
blast-furnace -operators indicated that the Leone system was not widely
accepted by the iron-making industry. It was not possible, within the
time frame of this study, to find out why the system was not accepted
and/or used. A logical question becomes: Was it technically or econo-
mically unacceptable? The claims made for the Leone system are of
interest to the topic of this study and Battelle researchers suggest
that a reexamlnation and evaluation of this system may be in order. The
ironmaking industry may have in hand information to confirm or refute
the Leone claims.
It is suggested that the Leone control system be examined in
the framework of technology of the 70"s. It is assumed that this report
will be read by blast-furnace technologists in many steel companies.
The authors of this report would appreciate receiving any information and
judgements concerning the differential pressure-control approach.
(4) Evaluate the Performance of Blast-Furnace "Cleaners" with Regard
to Lowering Slip Frequency
The use of cleaners to prevent or eliminate the buildup of
accretions on the inside walls of blast furnaces (and thereby lower the
-------
32
number of hangs. slips. and other o?erating irregularities) is somewhat
controversial within the blast-furnace industry. Some blast.-furnace
operators believe in .the copious use of cleaners. such as calcium chloride.
to reduce and/or remove the accretion fo~tions. while otheTs do ~ot.
In many instancEos those that do not advocate cleaner usage have had little
or no improvement in blast-furnace performance when they incorporated
clean~rs in their practices.
The teI'!ll. "cleaners" in this instance includes both "mechanical"
cleaners (selective use and placeme~t of scrap iron and coke to scour the
furnace lining) and "ch~mical" cleaners (such as calcium chl,~ride addi-
tions) to assist in th~ removal of detrimental alkalis. from blast
furnaces.
It appea=s to the Battelle researchers that the ~~eel industry
would benefit from a systematic study of the use of cleaners as a ~ethod
f~r improving blast-furnace performance. It is considered probable that
studies are being conducted at individual steel companies on this
subject. However. a joint effc.t. partic~larly if this has not been
done. should be beneficial.
-------
(1) Slater, J. H., Round Table Discussion on Special Phases of Blast-
Furnace Operations - The High-Prassure Furnace, Blast Furnace.
Coke Oven, and Raw Materials Con-jiicr.ee irr'oc.. AIME, Vol. 6, 1947,
p 112.
(2) Slater, J. II., "Operation of the Iron Blast Furnace at High Pressure",
Yearbook of the Anarican Iron and Steel Institute for 1947. May 21,
1947, p. 151.
(3) Leone, 0., Written Discussion to Paper presented by Fulton, L.,
Proc. Blast Furnace, Coke Oven, and Raw Materials, AIME, Vol. 9,
1950, p 306
(4) U.S. Letters Patent No. 2585800, K. C. LeViseur and L. Larson,
Inventors, "Bleeder Aad Equalizer For Blast Furnaces", Issued
Feb 12, 1952. -
(5) Final Technological Report on A System Analysis Study of the
Integrated Iron and Steel Industry (Contract No. PH 22-68-65)
to Division of Process Control Engineering, National Air Pollution
Control Administration, May 15, 1969 (Prepared by Sattelle
Memorial Institute), p v-8.
(6) The Making. Shaping, and Treating of Steel. Ninth Edition, U.S.
Steel Corporation, Pittsburgh, Pennsylvania, 1971.
(7) McBride, D. and Miller, R., "Design and Operations of Youngstowii's
32-ft. Hearth Blast Furnace", AIME Ironmaking Conference Proc.,
1968.
(8) Towndrow, R. and Banks, W. "Some British Aspects of High Top-
Pressure Operation" AIME Proc. Blast Furnace, Coke Oven, and
Raw Materials Conf.. Vol. 12, 1953, p. 257
(9) Letter dated Fabruary 2, 1976, to Mr. Howard Weisz, Administrator,
Bureau of Air Pollution Control, Pittsburgh, Pennsylvania,
containing Blast Furnace Slips Records for weeks of 12-22-75
and 12-29-75.
(10) Rules and Regulation, Article XVIII, Air Pollution Control,
Allegheny County Health Department, Pittsburgh, Pennsylvania,
Effective Date June 15, 1972, p 16.
(11) Letter frcm Gregory S. Travassos, Division of Air Pollution
Control, Department of Public Health and Welfare, City of Cleveland,
Ohio, to Mr. Harold Lownie, Battelle Columbus Laboratories,
Dated March 1, 1976.
(12) Progress Report f/6, "Blast Furnace Cast House Emission Control",
prepared for U.S. EPA by Bets Environmental Engineers, Inc., under
Contract No. 68-02-2123.
-------
(19)
(20)
(21)
(22)
(23)
(21.)
"4
(13)
Mattis, R.P.. "An Evaluation of Charging and Tapping Emissions For
the Basic Ox~'gcn Process". 68th Annual :1-!(!'..t Fur.lace", Proe. ~last Fu-rtace,
foke Oven, and Raw Materials Con0!!~~.. AlME, Vol. 13. 1954, p.208.
Sagawa, K. and Ishikawa, H., "Analysis of Factors Limiting the
Blast Furnace Prod~ctivity". Transactions ISI~, Volume 8, 1968,
p. 172. .
Archibald, W., Brown, T. and Leonard, L., . "Prop()sal for a Self
Lining Blast Furnac~", Journal Iron and Steel' Institute, Vol. 188,
September 1957, p. 32.
Fulton, L., "Lessons from a Hanging Blast Furnace", Froe. Blast
Furnace, Coke Oven, and Raw Materials, AL~, Vol. 9, 1950.
Wagstaff. J., "A r..eport on Solid Movecent in Blast Furnace Models",
Froc. Blast Furnace, Coke Oven, and Raw Materials. AIME, Vol. 14
1955, P 298.
Notini. U., "Experience with Sinter Burden in Swedish Blast-Furnaces",
Journal Icon and Steel Institute, Vol. 189. August 1958. p. 322.
-------
(25)
35
Larsen, B., "Some Questions on Interrelated Processes Going On in
the Blast F,urnace", Proc. Blast Furnace. Coke OVt:!n. .md Raw Mater1'a 1,
AlME, Vol. 6, 1947, P. 118.
(26), Blast Furnace - Theo!.Y.2.nd Practice, Vo1u:np. 2, J. H. Strassburg~r -
~d. Gordon and Breach S~ience Publishers, ~ew York, 1969, p. 306.
-------
36
APPENDIX A
FACTORSCONTRIBU'rING TO BI..AST-Ft1R"~ACE HANGING
-------
JI
Factors Cont~ibutin~ to Bl~st-Fur~ace Han~ing
At least five separate causes of hanging have been
proposed. (6 )*
(1)
Previously fused slag and molten iron may
resolidify by passing from a hotter to a
cooler region of the furnace or by alteration
of composition, thereby causing an impervious'
mass, which in turn interrupts the smooth
movement of the stock.
(2) An excessive quantity of fines (i.e., relatively
small parcicles) in the coke and/or insufficient
. (3)
coke stability, wherein the coke fines' become
. wedged becween the larger coke particles and
. .
lumps, thereby restricting the gas fl~ and
. .
. causing arching of solid material in the furnace.
Fine carbon formed via the Boudouard reaction
(eC2 + c ~ 2CO) may also fi 11 th" interstices :Ji
the burden and, in turn, impede the upward flow
of gases.
(4) Alkalis, such as the oxides of sodium and potassium,
may also contribute to the hanging condition. In.
many instances, the alkalis lead to the formation
of accretions and. scabs which adhere to tbe furnace
wa 11 s .
These formations then interfere with the
(5)
distribution of gas inside the furnace and prevent
the smooth downward movement of the burden.
Overblowing the furnace, or an exc~~8 of air (wind)
introduced to the furnac6 relative to the character
(i.e., permeability) of' the particular burd~n may
contribute.
Various physiochemical models which incorporate the above
factors have been developed to predict and/or explain the onset of hanging.
* References are given on page 33.
-------
38
For example, one model which is frequently used to describe hanging in
the bosh section of the furnace is based vn the phenocenon known as
"flooding", which occurs _'hen the force of the descending fluid (e.g..
.. the liquid slag) balances the force of the a.>c':!nding gas. When the flooding
condition occurs in the bosh. the liquids are carried back up the furnace
in~o a lower temperature region, where they resolidify. An impermeabl:!
region is formed and. ..5 a consequence, the
remaining open portion
. aggravating situation.
. . two parameters. a fluid
of the bed increa5Cs
. (16)
Elliott. et a1,
gas velocity through ~he
thereby generating a self-
dev~loped a correlatio~ betwe~~
ratio and a hanging ratio, which in turn can be
. used to deriv~ a critical condition for the onset of hanging du~ to bosh
floOding. Thi$ proposed critical ccndition is given by the relation:
(hanging factor)2 x fluid ratio <103.
CA.l]
where the hanging factor is a set of parameters which is essentially a
balance between the opposing forces of !.:U~ liquid and gas across the bed.
and' the fluid rati, is a measure of the relative amounts of gas and liquid.
Introducing further assumptions about the conditions existing
withir. the bosh zone. a critical bos:' flooding criterion can be .stated
as:
\l
(D2~)
< Cl
I
(A-2]
. I
where
W . wind volume (m3/second)
. D ~ ~last-furnace inner diameter (m)
'Ce.. mean coke size (mm)
, r';l ,
Cl . hanging factor,t see J
The relation given in Equaticn [A-2] indicates that, for hanging
not to occur as a result of floodbg. the wind volume divided by the
product of tte square of the furnace diameter and the square root of the
mean coke size ~ust be less than the Cl value. For several blast-
1m (17)
furnace operations. Cl has a value of about 2.1--- .
sec
"
-------
39
Although the bOJh flooding model and other models are extremely
valuable for understanding the complex interrelations among the furnace
operating para~cters whic? contribute to hanging, 00 model is sufZicicntly
developed to fully defil1ethe conditions whereby the hanging phenonenon
can be totally eliminatedwit:hin a working furnace.
Practically all the models and formulations of the hanging
pehnomenon indicate that the frequency of occurrence of hangs (and, in
t~rn, slips) should diminish as the permeability of the burden increases. (18)
Wh,ile the burden pe~tability can generally be improved by stabilization
of the physical anci chemical properties of the charged matetials, there
is' a limiting valu, to whlc.h the p~rmeability can be increased without
significantly redu...ing furnace produc~ivity.
As recogni:.ed"bynumerous workers, hanging, and in turn the
, .
, "
conditions' required to ,minimize hanging, is but one factor which determines
furnace productivity.(l9,20)ror example, Segawa and Ishikawa(20) defined
a sult~blc range of operating variables (i.e., acceptable combinations of
coke and ore size, wind, and furnace diameter) by assuming that the four
phenomena o,f (1) hanging due to flooding, (2) blowing through (channeling)
of the gas, (3) heat transfer between gas and solid, and (4) redcction of
iron ore, were the major factors determining productivity. The r~sults
of Sega~a and Ishik4wa's calculations are shown in Figure 6.
These tesults (e.g., Figure 6) are not presented in any absolute
sense, but mert:.l}' to indicate that the hlinging phenomenon is but one factor
to be considered in the operation of any blast furnace.
The conditions causing and associated with a hanging furnace
are discussed in greater detail in Referen~es 16 through 26.
-------
120
100
E
~ 80
-:
C>
N
';jj
C> 6()
~
:) .
(,)
E
E
~ ~o
~
"
';; .
:.
:.
FIGURE 6.
40
,
I
I
\1 .
-,----'--
40
200
~o
mJ'minl
so
60
.,/
20
~LI
m: 'nli",}
SUITABLE OPERATI~G RANGE FOR A
BLAST ~~ACE(20)
(a)
W
D2
W
D2
Coke. size versus
(b) . Ore size versus
-------
41
APPENDIX B
LETTER RESPONSE OF THE AMERICAN IRON AND STEEL INSTITUTE (AISI)
TECHNICAL COMMITTEE ON BLAST FURNACE PRACTICE
CONCERNING AVAILABILITY OF DATA OS SLIP-INDUCED BLEEDER-VALVE EMISSIONS
-------
C 0 ~"i I T TEE
42
CORRESPO;.iDESCE
~'''O "'" 2 5 lr1"
,~..." .):";;', 'J/G
COMMITTEE:
AISI Te(:hnical Committee .on
Blast Furnace Practice .'
."'DURESS WRITER CARE OF:
Interlake, Inc.
10730 Burley Avenue
Chicago, Illinois 60617
SUBJECT:
Battelle Stu~y -
Blast Furnace Slips
DATE:
June '8, 1976
Dr. Carroll Mobley
Research Metallurgist
Primary Operations Section'
Battelle .
Columbus Laboratories
505 King Avcnue .
Columbus, Ohio 43201
Dear Dr. Mobley:
On May 18, 1976 you wrote toMr.W; C..Benzer of the AISI coucerning the Battelle
Study on Blast Furnace Slips.' .
. . .
This letter was discussed in the recent meeting of the Technical Committee on Blast
Furnace Practice and, as the newly appointed Chairman, I have been designated to
!espond. .
Basically the information requested in the proposed questionnaire is not available.
Obviously some of the design information could be made available such as "normal
operating top pressure" but the companies are not recording such information as
"the number of slips per month which open dirty gas bleeder valves".
We realize that Battelle has been commissioned to study the problem and as such are
under an obligation to perform. We would like to aid you in this but .since the
information is not available we see only two alternatives: (1) that representative
companies would install recording instrumentation to obtain the desired information
--- this would take time and would be costly, and (2) Battelle would p~t observers
in the field. This too would be costly and time consum~ng.
1:1 all sincerity we feel that the current operating practi.ce of blast furnaces with
the relative rare slip that opens the dirty gas bleeder dces not constitute an acute
pollution problem. Therefore, the value of such a study is questionable.
1 have discussed these and various other factors relating to the study with Mr. Hoffma'
.of Battelle and will be glad to pursue them further with you if you so desire.
Sinr.erely,
"""
',./ \. . '"
. .-- . ; t~ .~ "- '~ - \.. ...~.. '.
jwc!/wd
cc: B.W.H. Marsden.
W.C. Benzer
J. W. Duncan, Chairman
Technical Committee on Blast
Furnace Practice - AISI
-------
43
APPENDIX C
SECTION 1810.5: . STANDARDS FOR SOURCES - BLAST-FUR~iACE SLIPS
RULES Ala> REGULATION; ARTICLE XVIII, AIR POLLUTION CONTROL
JUNE 15, 1972, ALLEGHENY.CO~TY HEALTH DEPARTMENT
-------
.5 Blast Furnace Slips
A. Emissions from blast furnaces shall be kept to a minimum. No person
shall cause, suffer, or allow any blast furnace to emit air contaminants, es a
result of a slip, more than sixty (60) times in any consecutive twelve (12) month
period or more than ten (10) time) in any consecutive thirty (30) day period.
For the purpose of this Subsection, a blast furnace slip ;,s defined as a sudden
emission of gas containing particulate matter of an opacity (.qua) to or greater
than No. 2 of the Ringelmann Scale or of an equivalent opacity from the relief
valves at the top of the furnace.
B. No person shall cause, suffer, or allow the operation of any blast
furnace without providing a device for measuring and recording all blast furnacv.
•lips. Suet, device or devices must be approved by the Director.
C. All devices used for observing and recording blast furnace slips shall be
maintained in good order. Safe and adequate means t'or inspection of such
devices shall be provided by the person responsible for the blast furnace.
D. All persons responsible for blast furnaces shall make available to the
Director, on request, the records of the required observation and recording
devices. These records shall be deemed as an admissipn by the responsible person
of the number of blast furnace slips occurring, but they shall not be deemed a* a
limit on the Director's action to present evidence that a greater number of slip*
occurred than the records indicate.
-------
45
APPENDIX D
. .
ALLEGHENY'COL~TY' HEALTHDEPARTME~T DATA
on
SLIP-INDUCED BLEEDER-VALVE OPENINGS
PER MONTH FOR A FOUR-YEAR PERIOD
-------
BLAST-FURNACE SLIP-INDUCED BLEEDER-VALVE OPENINGS PF.R MONTH OVER A^FOUR YEAR PERIOD
(ALLEGHENY COUNTY HEALTH DEPARTMENT DATA)
Blast
Furnace
Works it Year
Plant A 1 1972
1973
1°74
1975
3 1972
1973
19 T>
1975
4 1972
1 Q7T
i 7 1 J
1974
1975
6 1972
1973
1974
1975
7 1972
197H
1974
1975
Plant B 1 1972
1973
1974
1975
2 1972
1973
1974
1975
1
.
-
-
-
0
0
0
1
0
0
3
4
0
8
1
.. '
3
15
9
0
0
1
-
0
1
0
-
2
.
-
-
-
0
-
0
0
0
0
0
7
-
0
0
_
-
5
13
0
0
0
0
7
0
0
-
3
.
-
-
-
0
1
0
1
0
0
0
10
3
3
0
.
4
6
7
0
0
0
0
2
2
0
-
4
.
.
-
-
0
0
0
p
0
0
0
12
17
4
0
.
0
30
10
0
0
5
0
0
6
I
-
5
2
No
No
No
0
0
1
0
0
1
2
1
11
8
0
2
11
61
13
4
0
o
0
7
7
3
-
Month
6 7
3
Data -
Data -
Data -
0
0 0
4 4
0 0
0
11 1
2 4
13
1 0
5 7
Down-
3
5 12
50 29
8
0
Down
Down
Down
0
0
0
0
_
1
3
2
13
9
-
36
29
9
7
-
-
-
2
0
2
2
_
4
4
9
0
2
-
7
11
24
10
3
-
•
-
b
-
2
-
_
0
-
4
-
1
-
3
-
4
11
2
-
-
-
_
2
0
-
_
2
-
0
1
-
-
2
14
4
12
0
-
-
-
0
-
1
-
.
0
- .
0
0
-
0
-
3
5 Down -
0 0
0.0
4 4
0 0
13 68
3 4
2 6
-
—
1
0
0
_
0
0
1
1
0
0
0
1
0
0
0
2
0
0
-•
6
0
0
-
1
0
0
-
2
0
-
-
.
-
2
-
_
-
-
-
Bleeder-Valve
Openings Reported/
Number of .Months
17/7
2/10
3/9
14/12
4/9
0/6
20/12
18/9
62/11
46/10
47/10
1/5
17/7
96/9
260/12
62/6
8/10
1/11
16/12
0/8
106/10
23/11
12/10
1/2
Yearly Avg
Bleeder- Valve
Openings/Month
2.
0.
0.
1.
0.
0.
1.
1.
5.
4.
4.
0.
2.
10.
21.
10.
0.
0.
1.
0.
10.
2.
1.
0.
4
2
3
2
4
0
7
7
6
6
7
2
4
7
7
3
8
1
3
0
6
1
2
5
-------
BLAST-FURNACE SLIP-INDUCED BLEEDK.1-VALVE OPENINGS PER MONTH OVER A FOUR YEAR PERIOD
(ALLEGHENY COUNTY HEALTH DEPARTMENT DATA)(CONT.)
Blast
Furnace
Works 9 Year
Plant B 3 1972
1973
1974
1975
51 1*79
X 7 / *
1973
1974
1975
6 1972
1973
19/4
1 Q 7 C
A 7 1 J
Plant C 1 1972
1973
1974
1975
Plant D 1 1972
1973
1974
1975
3 1972
1973
197/-
in?1;
Month
J
—
34
46
32
0
89
33
4
18
0
23
1
0
0
8
3
0
0
5
19
6
n
2
—
16
15
47
0
62
3
66
8
0
13
2
0
3
—
65
32
25
0
78
1
84
12
0
14
0
0
4
2
53
6
23
0
56
0
87
0
5
13
0
0
5
8
21
2
23
0
60
1
127
-
4
9
0
0
6
0
156
6
28
0
46
0
106
Down
27
2
0
0
7
3
22
6
5
0
31
3
10
-
46
0
0
8
—
. 4
3
4
53
11
9
31
16
5
5
47
11
10 11
14 19
18 25
52 77 ,
Banked
70 92
48 Down
12
—
-
75
_
-
Banked - -'•'-.
_
.'
26
0
0
0
-
24
1
0
0
3 80
- .
29 Down
0 0
1 0
0 Down
.
-
-
0
0
-
Banked
22
10
0
0
2
17
1
n
19
1
0
0
1
15
.
4
2
0
5
8
5
6
1
0
0
-
4
2
9
13
0
0
-
3
21
0
0
0
0
-
0
0
0
0
0
0
0
1
0
0
0
0
0
-
17
49
0
0 0
0 0
0 0
-
8 83
8 74
0 Down
0
0
0
-
70
-
-
(Untro^l _._-----
Bleeder-Vaive Yearly Avg
Openings Reported/ Bleeder- Valva
Mumbei of Months Openings/Month
77/7
430/11
: 325/12 ,
m/£
262/11
492/10
41/7
567/10
38/4
161/10
75/10
4/12
0/10
0/1
73/12
16/12
0/12
5/5
202/12
210/11
22/9
0/2
11.0
39.1
27.1
21.3
23.8
49.2
5.9
56.7
9.5
16.1
7.5
0.3
0.0
0.0
6.1
1.3
0.0
1.0
16.8
19.1
2.4
0.0
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BLAST-FURNACE SLIP-INDUCED BLEEDER-VALVE OPENINGS PER MONTH OVER A FOUR YEAR PERIOD
(ALLEGHENY COUNTY HEALTH DEPARTMENT DATA) (CONT.)
Blast
Furnace
Works
Plant D
Plant E
Total for
•^•^•••••^•M* O^MHMV
f
tf Year
4 1972
1973
1974
1975
6 1972
1973
1974
1975
1 1972
1973
1974
1975
Allegheny Count
1972
1973
1974
1975
1
1
0
0
0
3
0
0
0
0
0
-
0
3.
2
0
0
0
0
0
0
0
0
0
0
-
3
0
0
0
0
0
0
0
0
0
1
-
4
1
0
0
0
0
2
0
0
0
5
0
0
0
0
0
0
0
0
0
Month
6
3
0
0
0
1
0
0
0
0
7
2
0
0
0
0
0
0
0
0
8
0
0
0
0
0
0
-
0
0
9
0
0
0
0
0
0
-
0
0
10
0
0
0
-
0
0
-
-
1
11 12
0 0
0 -
4 0
-
0 1
0
0 0
-
0 0
Down --------
-
-
-
0 Down -
Plants
and
Blast
Up
0
Furnaces
0
0
0
-
-
Bleeder-Valve
Openings Reported/
Number of Months
7/12
0/11
4/12
0/9
5/12
2/11
0/9
0/9
1/12
1/3
0/2
0/4
Yearly Avg
Bleeder- Valve
Open ing s /Month
0.6
0.0
0.3
0.0
0.4
0.2
0.0
0.0
0.1
0.3
0.0
0.0
Reporting
1144/138
1128/124
1373/144
324/84
8.3
9.1
9.5
3.9
c
o
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49
APPENDIX E
ESTIMATE OF QUANTITY OF GAS AND DUST
ASSOCIATED WITH A BLAST-FURNACE SLIP
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50
Estimate of Quantity of Gas and Dust
Associated With a Slip
To estinate the amount of gas and dust occurring during a slip.
Che "piston" model is assumed applicable. In this model, the slip occurs
when the upper portion of the burden falls to fill a previously existing
cavity. One measure of the severity .of the slip is the "fall" distance
of the burden, or, in turn, the dimensions of the cavity. Assume that
the cavity dimensions are the height, h, and the furnace diameter, d.
Then the cavity volume, V, is T dlu The number of moles of gas contained
within the cavity and, in turn, released during the slip can be calculated
via the ideal-gas relation.
.. •' £;:- - --5 ' *•»
The number of moles of gas generated for a 2-foot (0.6096 m) slip in a
30-foot (9.144 m)-diameter blast furnace, wherein the gas pr*>;sure
within the cavity, p, is taken as 29.4 psi*. absolute (2 atmospheres)
and the temperature is 927 C (1200 K), are
2 atm • 40008 liters
n - 0.082 atm-liter • 1200 K - 813 moles (E-2)
°K-mole
The approximate gram-molecular weight of the offgas is 30
g/mole. The total mass of gas released is then about 24.4 kilograms,
or about 54 pounds. . .
Converted to standard temperature and pressure conditions,
the 813 moles of gas represents 18200 liters (643 SCF).
The dust loading of blast-furnace offgas is in tne range
of 2 to 30 grains** per standard cubic foot for "normal" operating
The gas pressure vithin the cavity must be equal to or less than the
blast pressure an
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51
conditions. Under slip conditions it is reasonable to expect the dust
loading to be greater than the norcal value. Assuming that the. dust
loading is 10 to 100 times the maximum normal dust loading (i.e., 300
to 3000 grains/SCF) implies that 28 to 276 pounds of dust is contained
in the slip-generated gas volume. Thus an estimated quantity of dust
in the range of 28 to 276 pounds would be emitted per "2-foot" slip
in a 30-foot-diameter furnace if the entire volume of slip-generated
gas were released from the dirty-gas bleeder valves.
These estimated quantities of dust associated with a slip are
considered conservative (i.e., it is doubted that the actual quantities
of dust released exceed these estimates). For example, a 2-foot-high
cavity would seldom, if ever, exist across the entire diameter of the
furnace. Other input data, such as cavity gas temperature and pressure,
are believed to be realistic estimates of the actual conditions as-
sociated with the slips.
Also based upon this model, the quantities of gas and dust
generated in a given fall height slip should scale directly with the
furnace diameter squared. Thus the quantity of the oust emitted from
given fall slips should be less in smaller diameter furnaces than large.
The above calculation and assumptions are offered as a means
of arriving at an order-of-oagnitude value for the quantity of dust
emitted from a dirty-gas bleeder-valve due to slips. To the best of
our knowledge, no data exist to confirm or refute the estimate presented.
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52
APPENDIX F
COPY OF U.S. LETTER PATENT ON
"BLEEDER AND EQUALIZER FOR BLAST. FURNACES"
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53
Feb. 12, 1952 K. G. LE VISEUR ETAL 2,585,800
BLEEDER AMD EQUALIZER F03 BUST FURNACES
Filed Sept. 3, 1947
ZT
KURT G. LE VISEUR V
LEONARD LARSON.
ov
BY
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Patented Feb. 12, 1952
UNITED STATES PARENT OFFICE
2.U5.SM
BLKEDEB AND EQUALIZER FOB BIJ18T
FUBNACE8 :
Kart O. I* Vbeor. Yoaacitown. and
Lanon, Shaker HelghU. Ohio, assignor* to Be-
pablie Steel Corporation. Cleveland, Ohi*. a
corporation of New Jersey
Application Septcaber 1. 1947. Serial Ne.
5 Claim*.
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8,685,800
Ben chamber 29 Is provided with a bleeder pipe
II equipped with a valve 21.
Bleeder valves II and 22 are of the type which
open against gas pressure within the bleeder
pipes, as by downward movement of the long. a
lever arms 27 against the counter-weights 21 on
the short lever arms. Means are provided for
opening these bleeder valves at different selected
gas pressures within the bleeder pipes. This
apparatus Is substantially a. follow*, etarting
with a furnace in operation wlU. gas pressure
above the stock line in the furnace of. for ex-
ample, t> pounds p. s. L gauge, the valve 24 closed
.and valve 20 open and bells IK and II closed, and
the stock rod weight 44 being down at toe stock
line in the furnace. A quantity of furnace charge
la brought into the totaling hopper whose bot-
tom Is closed by smat bell 17. The small beU 17
means Includes the system of piping, valves and 10 I* lowered and the charge la discharged Into
cylinders, shown in Fig. 1. A pipe line 21 leads
.from one uptake II and is divided into two
branches. One branch II leads to a diaphragm
II which operates a valve 12 to control the flow
of fluid from a supply 12 to a cylinder 14 pro-
vided with a piston 15 attached by cable II to
the lever arm 27 of bleeder valve 22. The other
branch. 17. leads to a similar diaphragm lla.
which operates a valve II to control the flow of
chamber 21 onto lares noted in installations
where such Independence Is desirable. la such
case Instead of cables 41 and 41 being connected
up and over a pulley 41 and then downward to a M "f
reel or other suitable means (not shown) for ac-
tuating the cable and raising and lowering the
stock rod. Another cable (I Is connected to
cable 41 and is wrapped around pulleys 47 and
'* ««• 2- «*«»» would «» tree and clear
of the other.
Having thus described the Invention so that
others skilled hi the art may be able to under-
stand and practice the same, we state that what
41 keyed, respectively, to the shafts of valves 24 «0 we desire to secure by letters Patent la denned
and 21. A counter-weight 41 is attached to the in what 1* claimed.
free end of cable 41. It will be understood that What U claimed Is:
1. The method of operating a blast furnace
having u bell chamber which comprises the step*
85 of removing from the furnace top gases carrying
entrained solids and having the pressures exist-
ing In U e furnace about the stock line, remov-
ing solids from substantially all of said gase*.
separating the thus cleaned gas Into a .eon-
valves 24 and 21 are so set relative to each other
that one la opened and the other is closed by
movement of cable 41 in either direction.
By reason of the connection of the valve ac-
tuating cable 41 with the stock rod cable 41. the
opening and closing of valves 24 and 21 is syn-
chronized with movements of the stock rod. The
O'lvementa of the stock rod cable are synchro- 70 stantly flowing stream and a stream flowing m-
uzed with movements of the large and small
charging bells by means of Interconnecting con-
trols which are conventional and form no part
of the present invention.
termlttently to said bell chamber; maintain.
ing the pressures of the gases while being
cleaned and in the streams of cleaned gases at
appraxlmateiy the pressures existing above the
The operation of thia Interconnected charging 15 furnace stock line, and releasing gases from the
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56
«,6S8,MO
intermittently flowing stream U> tlie atmosphere
when the pressure above the furnace stock line
and in last mentioned stream reaches a predeter-
mined pressure above the normal furnace stock
line pressure.
2. The method cf operating a blast furaac*
hiving a bell chamber which comprises the steps
of removing from the furnace top gases carrying
entrained solids and having the pressures exist-
ing In the furnace abcve the stocic line, removing
•ollda from substantially all of said gases, sepa-
rating the thus cleaned gas into two stream.
maintaining the pressures of the gases while being
cleaned and in the streams cf cleaned gases at
approximately the pressures existing above the 13 atmosphere and a branch outlet having a control
furnace stocc line, and periodically releasing gases valve to the bell chamber, a valve for said mam
from one of said streams into the bell chamber outlet, a valve for said bleeder, and means re-
ef the furnace and from'the. other stream Into spoiuive to said predetermined high pressure of
the atmosphere. • • . top furnace gases to open sold bleeder valve acd
3. The method of operating a blast furnace 20 means responsive to a predetermined gas pres-
havlng a bell chamber chlch comprises the steps - sure below said high pressure ana above normal
valve, said means being responsive to a predeter-
mined pressure of top furnace gases which is
below said high pressure and above the normal
top ens pressure.
5. lii apparatus of the class described, a blast
furnace having a bell chamber, a gas cleaner, a
conduit from said cleaner to a gas main, a con-
duit connecting the top of the furnace with the
cleaner to conduct top furnace gases to said
cleaner, a bleeder to permit escape of top gases
from the furnace when such gases attain a pre-
determined high pressure above their normal
pressures, a pipe communicating at one end with
said cleaner anJ having a main outlet to the
of removing from tee furnace top gases carrying
entrained solids and having the pressure." exist- •
Ing In the furnacs above the stock line, removing
colida from substantially all cf said gases, sepa- 25
rating the thus cleaned gas into two streams..
maintaining the pressures of the gases while '
being cleaned and In the streams of cleaned gases
at approximately the pressures existing above the
furnac* stock line, periodically releasing gases 30
from one of said streaov: Into the bell chamber
of the furnace during charging of solids into the
furnace and to the atmosphere from same stream
when the pressure above the furnace stock line
and in said itream reaches a predetermined pres- jj
•ure above the normal furnace stock line pres-
•uxe.
4. In apparatus of the class described, a blast
furnace having a bell eh&mber. a gas cleaner and
a conduit from said cleaner to a gas main, a con- ju
duit connecting the top of the furnace with the
cleaner to conduct top furnace gases to said
cleaner, a bleeder to permit escape of top gases
from the second conduit when such gases attain
ft predetermined high pressure above their nor- «.;
mal pressures, a pipe communicating at. one end
with laid cleaner and having a main outlet to the
atmosphere and a branch outlet having a control
valve to the bell chamber, a valve for said main
outlet, and means for opening said main outlet w 1947. pages 125 to 127.
top c*s pressure to open said main outlet valve.
KURT O. LE VISEUR.
LEONARD LARSON.
REFERENCES CITED
The following references are of record in the
file ol this patent:
UNITED STATES PATENTS
Number Name Date
721.418 Berg ... Feb. 24. 1903
759.991 Hamfeldt May 17. 1904
1.727.100 Edwards Sept. 3. 1929
1.856.897 Whltcomb May 3. 1932
1,881.272 Grtlll Oct. 4. 1932
2.200.488 Clemmltt et ftl. .... May 14. 1940
2.215.872 Pox et -.1. Sept. 24. 1940
2.408.945 Mohr. Jj.. et al Oct. 8. 1943
2.411.487 Whitcomb Nov. 19. 1946
2416,190 Dougherty July 25. 1950
OTHER REFERENCES
American Institute of Mining and Metallurgical
Engineers. Transactions. Iron and Steel Division.
vol.67 (1922).pages609and615.
J. H. Slater: "Operation of the Iron Blast Fur-
nace at High Pressure." Yearbook of the Ameri-
can Iron and Steel Institute for 1947, May 21.
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