Overview and EE&Cof Steel Industry in Japan

November, 2006
Hideyuki TANAKA
Program Leader,International Engineering Dept.
The Energy Conservation Center, Japan
ECCJ1

1. Recent status of Energy Conservationin Mini Mill Industry in Japan
2. EE & C Activities in EAF
3. EE & C Activities in CC
4. Energy Conservationin Rolling Mill Process
5. Transition of Total Energy Intensity(Crude oil equivalent) - Example ECCJ

2

(1) Trend of Crude Steel Production,
Operation Status in Japankton

EAF ratio = (EAF steel) / (All steel)

Converter
EAF ratio
EAF, Special steel
Open hearth
EAF, Ordinary steel

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(2) Energy Saving Technologies
in Mini Mill Process
Decrease of Input Power
Decrease of Heat Loss
Scrap

Scrap
Preheater

VVVF
Bag Filter
Ladle & Tundish

EAF

Continuous Caster Decrease of Holding Time

Regenerative
BurnerBillet Heat insulator
Furnace
DHCR (Direct Hot Charge Rolling)
Rolling Mill

Continuous Rolling
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Furnace Operation
Rod, Bar& CoilType 1
Type 2Connecting of Billet
Connecting of Bar4

(3) Energy Use in Mini Mill Factory(Products: Steel Bars for Concrete Reinforcement)
13%
10%
4%
52%
9%
12%

Ratio （％）

EAF (Power)
EAF (Chemical Reaction：O2、Oil、Others)
Auxiliaries of Steel Making Shop (Power)
Burner (Ladle+Tundish)Burner (Re-heating Furnace)
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Rolling Mill Shop (Power)

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(1) Transition of Technical Development(EAF-CC)
Period~ 1976
1976~ 1978
1979~ 1980

Introduction of
new Technologies
Traditional operation method
LF installation
Burners on wall
Furnace water coolingWider water cool area
High power factor operation
Carbon injection

Power Consum. Oxygen
Tap-Tap
m3N/t(kWh/t)Time (min)

Oil
L/t

176

560

10--147

497

123.2

110

390

202.8

1981~ 1984

SPH installation
Oxygen rich operation (PSA)
New casting machine

95345

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2.3

1985~

EBT installation
Installation of more wall burners

8532532

1.8

1988~ 2000

Bottom stirring
DC furnace (More than 20 f‘ces)
Aluminum arm, Slag detector
Powder casting or nozzle casting
Large tundish, EMS
Mist cooling
Ecoarc (Shaft furnace andcontinuous operation)

2001~ 2006
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63

Hot metal operation
Night time operation
Utilization of waste materials
200
6Tap to Tap Time (min)Power Unit
Consumption of EAF

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Tap to Tap TimePower Unit Consumption of EAF(kWh/t-good steel)(2) Trend in Operation Indices of EAF

7(3) Energy Conservation Activities
in EAF Process
1) Energy conservation in EAF shop
(EAF: Electric Arc Furnace (AC, DC))a) Increase of input energy● Enrichment of O2
According to above countermeasure■ Increase of Oil (Burner), Carbon,
Low cost alloys (Aluminum ash,Bundle made from Can, etc. )ECCJ8b) Increase of efficiency in input energy● PowerCommon (DC, AC ):○ VVVF control of electrode lifting
Introduction of Inverter control system○ Foaming slag control in refining stage, etc.
AC： Al-arm, Reactor (in case of enoughcapacity of power station andhigh voltage operation), etc● Other
Post combustion (Shaft furnace), Supersoniclance, etc.
ECCJ9c) Decrease of output energy● Increase of Heat size
● Decrease of Tap to Tap time and waiting timeof the time after tapping (from tapping to thestart of scrap charge)● Decrease of heat loss by slag
Hot recycle of slag, Control of scrap’s dust, etc.
● Scrap preheating
Shaft furnace with decreasing technology of dioxin2) Others● Power saving in auxiliaries

VVVF control of dust collecting fan motor, etc.
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10(4) Energy Balance-1Energy (kWh/t)

700
600

PowerMetal

500
380370400300C-combustion
2001000210
Metal oxidation
10037Slag100

Furnace loss

140

Off gasMetal oxidation
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Output11(5) Enriched Oxygen Operation (Example)
Melt down andRefining Stage

Melting Stage

Coke

Slag Foaming
Detector

Coke

O2
O2
Manipulator /EBT
Water Cooled Lance
Fe + 1/2 O2 = FeO 1.15Mcal/kg-Fe
FeO + C = Fe + CO - 0.68Mcal/kg-Fe
C + 1/2 O2 = CO 2.2Mcal/kg-C#1 Me.

#1 Ch.

#2 Me.

Refining and Heating

Tap#2 Ch.

BurnerOxygenCarbon5.3kA5.3kA700V

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700V

675V

Time(min)12

3 kWh/t(6) Influence of Oxygen and Reheat
on Power Consumption

Oxygen 1m3N/t(m3N/t)
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(7) Relation between Transformer
Capacity and Tap to Tap Time of EAF
160

Tap to Tap Time (min)

140
120
100
80
60
40
0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

Transformer Capacity / Charge Weight (MW/Ch-t)
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(8) Scrap Preheater
Several Types of Recent Scrap Preheater
Consteel

Shaft Furnace

Twin Shell Furnace

Effect: 45kWh/t

Effect: 70kWh/t

Effect: 30kWh/t(Reported value)(Reported value)(Reported value)

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(9) Effect of VVVF
(Example of Power saving calculation)

Blower Motorof Direct DustCollector(970kW)
PowerConsumption
Difference(80t furnace)
Without VVVF
With VVVF
970・0.85・(min/60) 970・0.85・[1・11/60= 960kWh/ch.
+ 0.85 3・10/60+ 0.753 ・49/60]= 520kWh/ch.
960/80 = 12kWh/t 520/80 = 6.5kWh/t
5.5kWh/t
Operation rate: 100% 85% 75%

1 charge = 70 min: 11 + 10 + 49 min
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(10) Energy Control System
Standardized Operation and Reduction ofProduction Cost in EAF
Melting Control• Power control• Melting profile calculation• Raw/Submaterial feed control• Additional scrap charging &meltdown determination

Refining Control• Slag foaming guidance• Thermal model calculation• Metallurgical modelcalculation

Data Management

Other Functions• Statistical data analysis• Trend graph of kWh/t• Operation tracking andreporting (Electricity & fuel:daily & monthly report)
ECCJ• Correlation between kWh& oxygen• Etc.
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(1) EE&C Activities in CC(1) Energy conservation in Ladle and CC● Regenerative burner for ladle & tundish● Matching of the productivity between EAFand CC (Continuous Casting)(2) Energy conservation after CC● Billet heat insulating equipment● DHCR (Direct Hot Charge Rolling), etc.
● Matching of the productivity between CCand Rolling MillECCJ18

(2) Regenerative Burner for Ladle(Same System for CC Tundish)Exhaust Gas
Exhaust Gas
Switching Valve
Fuel Gas
920Mcal/h

Regenerator(Ceramics)
Fuel Gas
600Mcal/hEffect:Fuel Reduction Ratio= 51%[Condition]
・Ladle Capacity: 100 t
・Heating Period: 10 hours

Conventional
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RegenerativeBurner19

(3) Billet heat insulating equipment
This equipment maintain the billet temperature in
hot at waiting to the reheating furnace.
Steel Making Shop

BilletYard
Heat insulating
Direct Hot Charge
Rolling
600-800℃

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Hot charge
200-600℃

Reheating Furnace( Hot rolling Mill Shop)

Cold charge
20-200℃

20(1) Transition of Technical Development(Rolling Mill)
PeriodIntroduction of
new Technologies

Power Consum.
(kWh/t)

Oil
L/t

1995~

Regenerative burner

Oil reduction:
20~29%

2001~

DHCR (Direct Ht Charge rolling), andsubsidiary furnace (Heat keeping furnace)

Oil reduction:
52%

2001~

Endless rolling

2002~

Hot eddy current inspection

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(2) Energy Conservation Measures inRolling Mill Factory(1) Matching of the productivity between CC and Mill
(2) DHCR (Direct Hot Charge Rolling), etc.
(3) Reheating furnace:
Application of regenerative burner system(4) Energy saving of fluid machinery:
Pump, Fan, Air Compressor, etc.

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(3) Application of Regenerative Burner
Regular Industrial Furnace
High temperature exhaust!
Fuel

ExhaustHigh-performance
Industrial Furnace (1)Burner

Metal type heat exchanger
ExhaustBlowerRecuperator(metal)

BurnerFuel

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BlowerCombustion air23

High-performance Industrial FurnaceAlignment of a pair of burners with a built-in ceramic storage heat exchanger,combustion and exhausting in turn, temperature preheated of combustion air
Fuel switching valve

BurnerRegenerator(Ceramic)

Induced draft fanECCJ

Switching valves for air
supply & exhaust

Blower24

Merit of Regenerative Burner in Furnace• Energy – saving
 Effect of high temperature combustion air
over 1,000℃(Reduction of fuel = - 20%)

• Uniform heating
 Effect of the stirring of waste gas by cycliccombustion• Compact equipment
 Shortening of the furnace length by installingburners along the full length of the furnace
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(4) Effect of Heat Pattern Changein Re-hearing Furnace
Temperature（℃）
Temperature of re-hearing furnace
1200
1000
800
600

Temperature of heated material

400

Heat pattern Fuel usage
1.00.93

2000
Time
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(5) Endless Bar Rolling System• Loss reduction by eliminating of cutting off at
both ends of bars
• Reduction of the idle time before feeding eachnew billet and the factors for rolling errors• Drastic reduction in products of wrong
dimension or insufficient length• Reduction in energy cost ≒ 3%ECCJ27

Endless Bar Rolling - Welding
Flash Butt Welding
PreheatFBW

Rough MillIntermediate Mill

Crop shear(Billet)
orBar(Billet)
orBarPreset

Flash butt Welding

ECCJPlane28

(6) Energy Conservation System• Accumulation and analysis of the energy
consumption data
• Control and management of energy
consumption & intensity• Application of existing system examples
Energy monitor and analysis system– Local devices

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Energy Intensity (Crude oil equivalent L/t)

(1) Transition of Total Energy Intensity(Crude oil equivalent) - Example (50t/heat EAF)
250
221
185

200

173

171190150

159

Performance of energy conservationfor 5 years = 10.5%

154

143

Energy conservation
effect by continuous
rolling = 4.1% (FY2002)

100
Performance of energy
conservation for 3 years = 8.1%
50
Electricity / total= 85％Electricity / total= 93％ (estimate)Electricity / total
= 88％

0
1995
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1996

1997

1998
1999
Fiscal Year

2000

2001

2002
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Thank You

The Energy Conservation Center, Japan31