Technical study into the means of prolonging blast furnace campaign life

European Commission Directorate-General For Research And Innovation

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Industrial research and development
Coal - hydrocarbons

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• Publié par: EUROPEAN-COMMISSION-DIRECTORATE-GENERAL-FOR-RESEARCH-AND-INNOVATION
• Nombre de lectures: 77
• Langue: English
• Poids de l'ouvrage: 5 Mo

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ISSN 1018-5593
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European Commission
technical steel research
Reduction of iron ores
Technical study into the means
of prolonging blast furnace campaign life
STEEL RESEARCH European Commission
technical steel research
Reduction of iron ores
Technical study into the means
of prolonging blast furnace campaign life
D. Jameson, H. Lungen, D. Lao
British Steel pic
9 Albert Embankment
SE1 7SN
United Kingdom
Contract No 7210-ZZ/570
1 June to 1 December 1995
Final report
Directorate-General
Science, Research and Development
1997 EUR 17247 EN A great deal of additional information on the European Union is available on the Internet.
It can be accessed through the Europa server (http://europa.eu.int.)
LEGAL NOTICE
Neither the European Commission nor any person acting on
behalf of the Commission is responsible for the use which might be made of the
following information
Cataloguing data can be found at the end of this publication
Luxembourg: Office for Official Publications of the European Communities, 1997
ISBN 92-827-9912-3
© European Communities, 1997
Reproduction is authorized, except for commercial purposes, provided the source is acknowledged
Printed in Luxembourg CONTENTS
Page
OBJECTIVE 5
INTRODUCTION
3. OPERATIONAL PRACTICES
9 3.1 Productivity
10 3.2 Burden
17 3.3 Ti02 Addition
19 3.4 Instrumentation and Control
26 3.5 Tuyere Diameter
26 3.6 Off-blast Periods
29 3.7 Casthouse Practices
32 3.8 Production Rules
33 3.9 References
4. REMEDIAL ACTIONS 77
4.1 Gun/Spray
4.2 Enhanced Cooling8
4.3 Grouting and Welding of Shell 80
4.4 Replacing of Staves and Coolers1
4.5 Ancillary Equipment2
4.6 References 8
5. FUTURE DESIGNS 105
5.1 Fourth Generation Staves
5.2 Copper Staves 1°
5.3 Improved Refractories7
5.4 More Comprehensive and Reliable Instrumentation 110
5.5 Throat Cooling 11
5.6 Improved Hearth and Taphole Design 11
5.7 Furnace Designs and Dimensions2
5.8 References8
133 CONCLUSIONS PROLONGING BLAST FURNACE CAMPAIGN LIFE
British Steel pic
ECSC Agreement No. 7210.ZZ/570
Final Technical Report
1. OBJECTIVE
The objective of this study was to carry out a comprehensive literature review of techniques used
to extend the campaign life of blast furnaces and identify important aspects of operational
practices, remedial actions and future plant design, to establish cost effective methods of
extending European blast furnace campaign lives.
2. INTRODUCTION
In recent years there has been an increasing requirement to extend blast furnace campaign life:
In order to reduce hot metal costs, by reducing manpower requirements and capital
costs, steel companies have increased the size and reduced the number of their blast
furnaces. In many cases there is no longer a standby furnace to be brought into
operation during blast furnace rebuilds11'. Consequently, long campaigns with
minimum reline periods are essential.
The cost of rebuilding or relining a blast furnace can be very high and may represent
a large proportion of the total capital expenditure available to a company. In recent
years, the level of subsidy to the steel industry has fallen, following an increasing
degree of modernisation and privatisation. When funding for capital projects relies
directly on business profits, the cyclical nature in steel demand and prices will have a
major effect on the capital available, and it may be necessary to extend plant life until
improved trading conditions are predicted. In addition, the priority for capital
expenditure has tended to move towards the finishing end to improve product quality
and range, to increase sales and enhance profit directly. Consequently, this results ¡n
a reduction in the proportion of capital available in the primary end.
Techniques to extend blast furnace campaign lives have often been pursued more actively outside
Europe, notably in Japan, wheren lives have been steadily increasing since the 1970's.
Figure 2.1(2) indicates the operational results of Japanese blast furnaces of over 2000 m3 inner
volume for campaigns completed between 1970 and 1981. Towards the end of that period the
longest campaign was 7 years, with the production per unit volume approaching 5000 t/m3. Figure
2.2(3) dates from the mid 1980's and shows that there was an increasing number of furnaces,
many then still operating, with a campaign output above the 5000 t/m3 maximum indicated in
Fig. 2.1. More recent data, from a variety of technical literature, are presented in Fig. 2.3 which
illustrates how the campaign output of Japanese furnaces has increased further, with a figure of
10000t/m3 being exceeded in 1993. Completed campaign lives are typically 11-13 years, but
these values have been exceeded by furnaces whose campaigns are yet to be completed. Using information from recent EBFC Blast Furnace Constructional Features compilations, Fig. 2.4
compares the campaign output of European and Japanese furnaces over a similar time period.
Although the best European examples are approaching Japanese levels, in general the campaign
life of European furnaces is significantly lower.
A shorter campaign life may result from a lower level of capital investment, as rebuilding a blast
furnace for a longer campaign life involves additional capital cost. It could also result from a lower
level of development of new equipment and techniques, or from inferior operation. Figure 2.2
suggests that larger furnaces tend to have a slightly higher campaign output per unit volume. This
difference may result from larger furnaces generally being of more modern design or because the
cost of extending the life of a large furnace is lower per tonne of output gained and therefore is
more economic than for a smaller furnace. The viability of an integrated steelworks depends on a
continuous supply of hot metal, which on a works with a small number of large furnaces puts great
importance on long campaign life. Such furnaces are likely to be well instrumented and operated
to achieve this aim. Since Japan tends to have a greater proportion of large furnaces, this could
explain some of the difference between Japanese and European campaign outputs.
Traditionally, the limiting factor to blast furnace campaign life was damage in the lower shaft13'.
With improvements in operational practices (e.g. improved burden distribution control), remedial
actions (e.g. stave replacement, gunning, etc.) andd designs (e.g. improved cooling and
refractories), there are fewer problems in this area. Consequently, other regions which used to
have less effect on furnace life become more critical, e.g. throat armour and upper stack
refractories. Ultimately, as techniques are developed to extend the life of, and repair, the various
regions of the furnace, the most critical region becomes the most difficult region to repair, which is
generally considered to be the furnace hearth.
The techniques for prolongation of blast furnace campaign life will be reported in three categories:
Operational Practices - The control of the blast furnace process has a major effect on
the life of the furnace. The furnace must be operated in a manner to maximise
furnace life, compatible with production requirements. It will often be necessary to
modify operating practices as the campaign progresses and in response to problem
areas, to maximise the furnace life.
Remedial Actions - Once wear or damage that may affect the life of the furnace
becomes evident, engineering repair techniques must be utilised or developed to
maximise campaign life.
Future, Improved Designs - As improved materials and equipment are developed,
these should be incorporated into future rebuilds to extend the life of critical areas of
the furnace, where it is cost effective to do so. 5.000 - Χ· -χ» α*
E
2
o β/
> "ï rix ir Õ
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• •78 ·79 2.000
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ι ■ I ' I , 1 I ■
3.0 tP 5j0 GJD7.0
Campaign (years )
RELATION BETWEEN SERVICE LIFE AND PRODUCTION FIG. 2.1
OF BLAST FURNACES HAVING 2000 m3 OR MORE
INNER VOLUME IN JAPAN
CJ
=3
CU
"ca
1,000 2,000 3,000 4,000
Effectiveinner volume (M3)
INNER VOLUME vs CUMULATIVE PRODUCTION FIG. 2.2
OF BF BLOWN IN BETWEEN '65 TO '80
JAPANESE B.F. OUTPUT PER UNIT VOLUME
Improvements with time
19
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< o
. ­ " " H 8
o_ Λ ■ ■
h­ 6
D
O ,
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° 0
75 80 85 90 95
END OF CAMPAIGN(Year)
FIG. 2.3
CAMPAIGN PRODUCTION PER UNIT VOLUME
(B.F.s>1800m3T.V.)
Λ
co ΙΛ.
Ε
3S
co 10 -■
h
■ Japan
o Europe iβ
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(D
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(
CAMPAIGNLIFE(Years)
FIG. 2.4