a series on traditional japanese handicrafts: no. 370 ......traditional japanese handicrafts:...

No. 370December2008Published monthly by Public Relations Center General Administration Div. Nippon Steel Corporation

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Regular Subscription Cosmic Ray Muons in Ironmaking—Opening up New Potential for the Measurement of Internal Blast Furnace Conditions—

In this issue Feature Story

A Series on Traditional Japanese Handicrafts:“Masterpieces” by Munemichi Myochin

“Tsuku”(Metal fi tting attached to the tip of bow)It is manufactured from laminated metal and has a hollow structure. The tsuku is mistaken for a bracelet.

Munemichi Myochin: Born in 1942 in Hyogo Prefecture. In 1983 when he was named the 52nd head of his artistic lineage, he received the Skills and Meritorious Service Award of Hyogo Prefecture and was designated by Hyogo Prefecture as a “Traditional Craftsman.” In 1997, he was selected as a “Master of Japanese Sound” by the Japan Audio Society. Other major awards include the Great Prize and the Special Prize presented at the Japan Cultural De-sign Awards (2003) and the Arts & Culture Prize of Himeji City (2004).

Explosion of supernova and sun surface

Collision of oxygen and nitrogen

with atomic nucleus

Atmosphere

Nuclear reaction

To earth surfaceTo earth surface

Prim

ary cosm

ic rayS

econd

ary cosm

ic ray

Muon

π and k mesons

WWWWWW

Operating Roundup

Deferral of Construction of a New CGL at I/N Kote Nippon Steel, together with ArcelorMittal, has already started construction of a new continuous galvanizing line at I/N Kote, U.S.A. Taking into consideration the current sudden downturn of the North American automotive market, both companies have agreed on deferral of construction of the New CGL until such time when the partners will gain a perspective of recovery of the North American auto production.

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*1) Cosmic rays: Atomic nuclei and elementary particles that constantly bombard the earth from space. Cosmic rays prior to entering the earth’s atmosphere are called primary cosmic rays, while newly borne particles resulting from the collision of primary rays with the earth’s atmosphere are called secondary cosmic rays. Muons are secondary cosmic rays.

Cosmic Ray Muons in Ironmaking—Opening up New Potential for the Measurement of Internal Blast Furnace Conditions—

Comic rays*1) constantly shower the earth—with great numbers of them passing through our bodies and the structures that we have built on the earth. Nippon Steel currently promotes a cooperative research project between industry and academia on the use of cosmic ray muons (mu mesons) that employs experts who have been engaged for many years in muon research. The objective of this project is to use muons to ob-serve internal blast furnace conditions that could not otherwise be seen due to ultrahigh operating temperatures.

Under the guiding principle of “Research and En-gineering,” the Technical Development Bureau of Nippon Steel has established an integrated R&D system that extends from basic research to ap-plied research and plant engineering. With regard to the development of ironmaking technology, the first process in iron- and steelmaking is the pro-duction of molten iron having prescribed qualities

Ironmaking R&D Div. to Support the First Step of Ironmaking Process

The current issue highlights research and engineering on internal blast furnace observation technology using comic ray muons that is being undertaken at the Ironmaking R&D Div. of the Environment & Pro-cess Technology Center of Nippon Steel.

Technical Development Planning Div.

Steel Research Laboratories

Advanced Technology Research Laboratories

Environment & Process Technology Center

R&D Laboratories at Steelworks

Energy & Environment Process R&D Div.Ironmaking R&D Div.Steelmaking R&D Div.Steel Rolling R&D Div.Refractory Ceramics R&D Div.Instrument & Control R&D Div.Plant Engineering Div.Machine Engineering Div.System & Control Engineering Div.Civil Engineering Div.

Organization of Technical Development Bureau

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No. 370 December 2008

Operating Roundup

Feature Story

Deferral of Construction of a New CGL at I/N Kote WWWWWW


Masaaki Naito General Manager, Ironmaking R&D Div.Environment & Process Technology Center(Joining Nippon Steel in 1982; Academic specialty: metallurgy)

from iron ore (mainly Fe2O2) and coal (the reduc-ing agent) procured from overseas sources. The Ironmaking R&D Div. offers related courses of re-search that range from the discovery of research seeds to their implementation as practical applica-tions. These areas of study range from improving blast furnace ironmaking operations (increased production, reduction of the reducing agent con-sumption rate, etc.) and improving the quality of charging materials (imparting specified qualities) to expanding usable resource sources and pro-posing recycling technologies and new ferrous material processes.

Nippon Steel is demonstrating initiative in the world steel industry by promoting the operation of increasingly larger capacity blast furnaces, the use of greater volumes of inferior quality raw materials, and energy savings. Illustrating this is the commencement in May 2008 of full-scale low NOx-type coke oven operations at the Oita Works

that make the most of SCOPE21, the next-gener-ation coke manufacturing technology. The use of recycled plastic waste generated outside Nippon Steel has progressed steadily as a resource recy-cling technology.

General Manager Masaaki Naito of the Iron-making R&D Div. speaks as follows about the de-velopment of ironmaking technologies:

“Several of our research initiatives to cope with such emerging concerns as the spiraling cost of raw material and the need to further reduce CO2

emissions have been adopted as national re-search projects and are at the practical research stage. Among those projects that have been pro-posed at our initiative to achieve a 30% reduction in CO2 emissions are a highly reactive coal mate-rial application technology (reduction equilibrium-point control technology) and the conversion of the blast-furnace reducing agent from carbon to hydrogen (hydrogen ironmaking).

“We will not only cope with these pressing tasks. We also wish to promote R&D capable of sustaining dreams and romantic expectations. One such research theme, introduced below, is technology that uses muons to measure the in-ternal conditions of blast furnaces. In addition, we wish to use tie-ups with universities to transfer as widely as possible CO2 emissions reduction tech-nology and other world-class technologies origi-nating in Japan.”



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Hot air

Fe2O3Fe2O3Fe3O4Fe3O4

FeOFeO

FeFe

Sintered ore, lump oreLimestone

Coke

Cohesive zone

Tapping hole

CO, CO2, etc.

Sintered ore, lump oreLimestone

Coke　

Shaft

SlagMolten iron

Fig. 1 Elevation of Blast Furnace

Photo 1

No. 2 blast furnace at Oita Works

Fig. 2 Section of Blast Furnace

Section in the vicinity of tapping hole is apt to erode

Shell (7~8 cm) Refractory (carbon block)

Tapping hole

In the blast furnace, iron is tapped by removing (reducing) the oxygen contained in iron ore at a temperature of 1,500°C. A blast furnace is a giant, bottle-shaped high-pressure vessel with a height of about 40 meters and a bottom diameter of 10-plus meters. The daily capacity of one of these units is about 10,000 tons of pig iron, sufficient to produce enough steel for 10,000 automobiles. (Refer to Photo 1 and Fig. 1)

Estimating Unseen Internal Blast Furnace Conditions from Empirical Values and External Observation

Due to the characteristics of blast furnace op-erations, once started, they must continue under strict around-the-clock conditions and at ultrahigh temperatures. In order to support the internal structure of such blast furnaces, the walls and bot-toms are built using refractories with built-in water

piping for cooling. In particular, the side walls of the lower (hearth) section of the furnace, where the molten iron is stored, are built with an inner lining of approximately 2 m-thick carbon blocks (refractories) that are surfaced with a lining of alu-mina and oxide-type refractories (Fig. 2).



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Akihiko Shinotake Senior Researcher, Ironmaking R&D Div.Environment & Process Technology Center(Joining Nippon Steel in 1985; Academic specialty: reaction chemistry)

The furnace walls and bottoms are subjected to ultrahigh temperature conditions that cause steady erosion. Accordingly, the target durability of these sections is set at about 15 years for blast furnaces blown-in in the 1990s, whereas for blast furnaces blown-in in the 2000s, the target is more than 20 years due to progress in technologies that prolong service life. Currently, Nippon Steel conducts relinings of blast furnace refractories at intervals of about 15 years.

Senior Researcher Akihiko Shinotake says this about blast furnace relining:

“Refractories suffer erosion during furnace op-eration, but the erosion rate is not uniform. Local-ized erosion is caused by the flow of molten iron and slag over the furnace bottom. When the thin-nest section of the bottom wall is reduced to about 50 cm in thickness, operations are judged to be in danger. Relining of the blast furnace is scheduled prior to reaching that level. To do this, thermom-

eters known as thermocouples are inserted into the refractories at a position 5 to 15 cm from their external surface. These thermocouples are used by skilled on-site workers and engineers to estimate the thickness of the refractories. According to past statistical data, we know that the higher the tapping rate (pig iron production per furnace inner volume) of a blast furnace, the shorter its service life is.

“When verifi cation is made of the internal sec-tions of blast furnaces during relining, it is seen that the estimated values for refractory wall thick-ness match well with the actual values. However, due to improvements in the quality of carbon blocks and other refractory materials, there are cases in which allowances in wall thickness re-main. Refractory replacement costs several thou-sands of billions of yen, and if replacement can be prolonged until actually needed, the resulting reduction in annual relining costs is estimated to amount to one billion yen or more.”



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Comic-ray muons are elementary particles that were discovered in 1937. When primary cosmic rays (protons and electrons) reach the earth’s atmosphere, π and k mesons are formed. These mesons instantly decay to form muons, gamma rays, neutrinos and other elementary particles that shower the earth. (Refer to Fig. 3) Muons are lighter than protons but heavier than electrons and, because they have a charge, are easily de-tected.

Whereas protons and electrons can penetrate water, carbon, and iron to a depth of only 10 to 30 cm or so, muons are easily able to pass through larger objects. When muons penetrate high-den-sity substances, the number of muons that pass through is lowered. Conversely, observing the quantity of muons and damping levels allows for the measurement of a substance’s internal struc-ture.

Nippon Steel, in cooperation with the High

Development of Technology for Observing Internal Blast Furnace Conditions through Industry-Academia Initiative

Energy Accelerator Research Organization, has since 2004 carried out joint research on muons and has recently conducted a measurement test using muons. Specifi cally, the test was conducted on the hearth mantle extracted after the blowing out of the No. 2 blast furnace at the Oita Works. It was done with the cooperation of Kanetada Na-gamine (Emeritus Professor of the University of Tokyo) and Hiroyuki Tanaka (currently Professor, Earthquake Research Institute of the University of Tokyo), who at the time was promoting research on muons as a professor of the High Energy Ac-celerator Research Organization.

In the test, horizontally moving muons were utilized because of their high penetration capac-ity and the ease with which the testing conditions could be set. Two detectors were prepared by placing 10 cm-square boxes on 1 m x 1 m plastic scintillators*2) (four sheets per detector). These were installed in a line beside the bottom of the

Fig. 3 What Is a Cosmic Ray Muon?



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*2) Plastic scintillator: A scintillator is a fluorescent material that emits light when hit by a particle. Plastic scintillators are manufactured by mixing a light emitting material in plastic which then fl uoresces when particles enter in it.

Explosion of supernova and sun surface

Collision of oxygen and nitrogen

with atomic nucleus

Atmosphere

Nuclear reaction

To earth surfaceTo earth surface

Prim

ary cosm

ic rayS

econd

ary cosm

ic ray

Muon

π and k mesons


blast furnace to detect the number of muons that would pass through it; and the density length (average density x penetration distance) was cal-culated from the level of muon penetration (Fig. 4). Because vertically moving muons are low in fl ying frequency, the number of penetrating muons was measured over a specified term (about one month) to fi nd the density distribution.

The resulting measurements showed that the density of the molten iron actually left within the hearth mantle was nearly the same as for the refractories. Further, it is now known that the po-sition of both the molten iron and the refactories can be clearly determined by differences in their density.



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Fig. 4 Principle of Measurement for Muon Permeation Images of Internal Blast Furnace Conditions

Cosmic ray muons cause light to be emitted from a plastic scintillator; the light is then amplified and detected by photomultiplier tubes.

Two detectors are arranged in a line to identify the direction of movement.

Density growth is calculated from muon permeation levels

Comic ray muon

Detector 1

Detector 2

Detecto

r 1

Detecto

r 2

Computer recoding of every section in which muons cause a reaction


In 2004, at the No. 2 blast furnace of the Oita Works, which had just finished relining and re-sumed operations, measurement of the mass density inside the furnace and the amount of erosion on the furnace-bottom refractories was undertaken with the aim of testing whether or not the internal conditions of the blast furnace could be observed employing muons. As a result, the mass density (ratio of molten iron having a high density to coke having a relatively low density) mainly of molten iron and the level of refractory erosion were successfully determined. (Refer to Fig. 5)

Senior Researcher Shinotake concludes by saying: “Nippon Steel is applying for a patent on a scheme to estimate the refractory erosion by using muons to measure furnace-bottom mass density. In order to put this measurement system into practical use, we will have to direct additional efforts toward discerning refractory erosion con-ditions with higher accuracy. If the level of our understanding of the internal conditions of blast furnaces can be improved to include greater de-

High Application Potential of Comic Ray Muons

tail, the system can potentially contribute to the stabilization of blast furnace operations. We har-

bor great expectations for the steady development of this muon-based measurement system.



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Fig. 5 Estimating Amount of Refractory Erosion

0.93

0.92

0.91

0.9

0.89

0.88

0.87-20 0 20 40 60 80 100 120

0cm-50cm-100cm

As the bottom refractories are eroded and replaced with molten iron, the capacity of muons to pass through them is lowered.

Ratio of the strength at penetration side of blast

furnace to the strength at the reverse side of blast furnace

Refractory erosion amount (cm)

Measured value

A lot of refractory

A lot of molten iron

Measured value for which refractory upper surface position is changed

Route to transverse the refractory upper surface

Molten iron

Ratio of the strength at penetration side of blast furnace to the strength at the reverse side of blast furnace


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More about Nippon Steel on the website: http://www.nsc.co.jp

by D.Sc Hiroyuki Tanaka Specially-assigned Prof., Earthquake Research Institute, the University of Tokyo

The genesis of muon radiography is attributable to Luis W. Alvarez, winner of the Nobel Prize in Physics, who noticed the high penetration capacity of muons, which he in turn used to conduct a non-destructive inspection of the in-terior structure of a pyramid. Thereafter, trials of the non-destructive inspection of giant masses using the high penetrating capacity of muons were undertaken worldwide�these trials included surveys inside subways and counter-terrorism surveys to fi nd hidden nuclear substances.

When inspecting pyramids, detectors can be installed in a small inner room, but they cannot

be inserted into volcanoes, blast furnaces, or the columns of a completed building. Our re-search has made it possible to measure these targets from the outside by using horizontally moving muons.

In research conducted jointly with Nippon Steel, I came to understand firstly that the demand for highly accurate measurements requires detectors with higher resolution and secondly that certain restrictions apply to the in-stallation of detectors, such as the impossibility of using electricity or other infrastructure sys-tems in the periphery of a blast furnace. Future

primary tasks needed for the practical use of muon detectors are detector downsizing and the im-provement of space resolution capacity through enhanced accuracy.

I understand that all the experiments and surveys conducted in the current joint research with Nippon Steel, including technical improve-ments to the detectors and the accumulation of know-how, are organically connected and will contribute to the development of the entire fi eld of muon radiography.

Toward the Practical Use of Muon Radiography—Accumulation of Technical Know-how Promoted through Joint Research and Production-fl oor Surveys—

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a series on traditional japanese handicrafts: no. 370 ......traditional japanese handicrafts:...

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