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Contract project-2004
With Ministry of the Environment, Japan
Ministry of the Environment
Air Pollution Control Technology
In
Steel Industry
March 2005
Overseas Environmental Cooperation Center, Japan
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Air Pollution Control Technology
in Steel Industry
Committee Members
Chairman:Dr. K. Nishida, Researcher, Department of Urban and
Environmental Engineering, Kyoto University)
(Retired)
Member:
Mr. S. Iwasaki, Director, Metocean Environment Inc.
Dr. S. Fujii (P.E.), Takuma Co., Ltd.
Mr. Y. Ogino (P.E.), Environment Technology L.R.C.
Prepared by
Dr. A. Hogetsu (P.E.), Research Commissioner, OECC
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Raw materials yard
Coking
BF
COG refinerySteel manufacturing
processes
Steel mill l ives close together
with neighboring people
(Kobe Steel Kakogawa Plant)
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1. Iron & Steel Making Process and Air Pollutants
iron ore &
coking coal
sintering
machine
coke oven
hot stove blast furnace continuous
castingconverter pre-heating furnace
hot rolling cold rolling continuousannealing furnace
hot role steel
cold role steel
COGBFG
slagboiler
conveyer
d u s t
S O x
N O x
d u s t
S O x
N O x
S
O x
N
O x
N O x
d u s t
d u s t
d u s t
d u s t
d u s t
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2. Process of Electric Furnace Plant and Air Pollutants
scrap
preheater EBT ladle refining
furnace
ladle
tandish mold
electric
magnetic stirring
continuouscasting
s o o t
d u s t
d u s t
d u s t
s o o
t
d u s
t
o d o
r
w h i t e s m o k e
d u s t
EBT: Electric Bottom Tapping
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3. Coarse Particle Scattering Prevention
3-1 Coal Handling Process
dust collection
coal cargo
wind shelter fencewater
sprinkling
chemical
spraying
hopper
chemical dosing
water sprinkl ing
chemical
spraying
coke ovenscreening
quenchingtower
storage bin
dust
collector
coke production facility
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3. Coarse Particle Scattering Prevention
3-2-1 Coke Production Coal Charging Process
mounted on
ground
Centrifugal
decanter
Tar decanter
Coking chamber
Leveling bar
Combustion chamber
Water tank
Pre-duster
Connection valve
Venturi
scrubber to stack
Thickener
Spray
nozzle
coal
COG
dust col lector
mounted on charging car
Bump
ejector
COG
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3. Coarse Particle Scattering Prevention
3-2-2 Coke Production Coke Discharging Process
connection valve
coke guide
car
bag filter
Pre-duster stack
quenching car
suction hood
coke oven
Coke guide car Ground facilities
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3. Coarse Particle Scattering Prevention
3-3 Sintering Process
coke breeze
sizing
to BF
sinter sizing
mixer
raw material bin
bag filter
ESCSbag filter
sinter machine
cyclone
blower
t o s
t a c k
Desulphurlizer
Slag-gypsum process
ESCS: Electrostatic Space Clear Super
bag filter
coke
ore
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3. Coarse Particle Scattering Prevention
3- 4 Blast Furnace Process
coke bin
ore bin
BF
surge hopper hot stove
torpede car
slag ladle
c h a r g e c o
n v e
y e r
Q=13,000x2 m3
/m4 0.01 mg/Nm3
Q=4,800 m3/m
3 0.01 mg/Nm3
Q=13,000x2 m3/m
4 0.01 mg/Nm3
Q=1,400 m3/m
15 0.01 mg/Nm3
bag f.
bag f.
bag f.
wet s.
wet s.
bag f.Q=460 m
3
/m5~10 0.03 mg/Nm3
castingbed
Q=600 m3/m
12~15 0.02mg/Nm3
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3. Coarse Particle Scattering Prevention
3-5 Steel Manufacturing Process (Converter)Bag filter
EP
hot metal
Treatment center
alloyladle repair
desulphur slag scraper
hot metal pit
desulphurization center
tundish yard
building exhaust
7,500 m3
/m2 0.03mg/Nm3
1,800 m3/m
20 0.10mg/Nm3
7,500 m3/m2 0.03mg/Nm3
7,500 m3/m
15 0.01mg/Nm3
4,000 m3/m
2 0.03mg/Nm3
7,700 m3/m
5 0.01mg/Nm3
14,200x2 m3/m0.4 0.03mg/Nm3
ladle converter
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3. Coarse Particle Scattering Prevention
3-6 Electric Furnace
bag filter
directevacuation
Doghouse System
roof
evacuation
1 s t c h a r g e
2 n d c h a
r g e
T a p p i n
g
m e l t i n
g
m e l t i n
g
o x i d a t i o n
r e d u c t i o n
roof exhausting system
direct exhausting system
Conventional System
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4-1 Gravitational, Inertial & Centri fugal Dust Collector
4. Dust Collection System
m i n . p a r t i c l e
d u s t
section
Stokes’ Law
V=(g/ 18 )( 1- ) D2 (cm/s)
V: settling velocity (cm/sec): gas viscosity (kg/ms)
g: gravitational acceleration (cm/s2)
1: particle density (g/cm3)
: gas density (g/cm3)
D: particle diameter (cm)
Principle of dust collection ;
Centrifugal force (F) = mv2 /R (N)
m: particle mass (kg)
V: particle velocity (m/ s)
R: cyclone radius (m)
Gravity
Inertia
Centrifugal
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4. Dust Collection System
4-2 Scrubbing Dust collector
Pressurized
water type
Reservoir type Packed bed type
demister
demister demister
packing
Principle of Scrubber Dust Collector ;
venturi
dust
water
drop
media
water film
Scrubbers ;
Rotary type
water spray disc
impact disc
fan runner
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4. Dust Collection System
4-3 Filter Type Dust Collector Schematic of typical bag filter unit
filter bag
filter cloth
dust layer to
be shaken off thin film dust
Pi = P + Pth
PPd
twisting
aperture 50~10
Type:
(1) bag filter
(2) cartridge filter
Filter cloth:
(1) woven fabric
(2) non-woven fabric
Dust shake-off:
(1) intermittent
(2) contimous
Apparent filtration rate:Filtration Mechanism
0.3~10cm/s
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4. Dust Collection System
4-4 Electrostatic Precipitator
-
-- -
- ---
--
-
--
-
dischargeelectrode
d u s t c o l l e c t i n g e l e c t r o
d e
-
-
-
-
-
Principle of dust collection ;
discharge
electrode
gas distribution
plate
manhole
collecting
electrode
hopper hammering
device
high voltage DC
generator hammering
drive
Structure of EP
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4. Dust Collection System
4-5 Selection of Dust Collector Parameter
particle distribution
dust concentration
specific gravity
electric resistnace rate
flow ratedue point
gas temp.
Collector
Applicable
Particle
( m)
mmH2O)
Removal
rate
Equipment
Cost
(¥/ /Nm
3
/h)
Operating
Cost
(¥/ /Nm
3
/h)
Gravity 1,000~50 10~15 40~60
Inertial 100~10 30~70 50~70
Centrifugal 100~3 50~150 85~95 300~2,200 100~1,000Scrubbing 100~0.1 300~900 80~95 400~2,200 100~1,300
Filter 20~0.1 100~200 90~99 300~2,100 300~1,100
EP 20~0.05 10~20 90~99.9 400~4,400 100~1,00
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5. Desulphurization Technology
5-1 Flue Gas Desulphurization in Steel Mill
Method Reaction Byproduct
Activated
carbon
SO2+H2O+1/2O2 H2SO4 H2SO4
Caustic
soda
2NaOH+SO2 Na2SO3+H2O
Na2SO3+H2O+SO2 2NaHSO3
Na2SO4
Ammonia 2NH4OH+SO2 (NH4)2SO3+H2O
(NH4)2SO3+SO3+SO2+H2O 2NH4HSO3+H2
(NH4)2SO4
Slaked lime CaO+SO2 CaSO3CaSO3 + O2 2CaSO4
CaSO4
most popularly used methodIn Japan
Limestone - Gypsum Process
SOx Rem. 90%
limestone cheap
initial & operating cost economical
systems stabili ty stable & safe
gypsum marketable
5 Desulphurization Technology
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5. Desulphurization Technology
5-2 Limestone-Gypsum Process
Gypsum
Flue Gas
Water
Cooling
Tower Absorber Demister
After Burner
Lime Tank
pH Control
Oxidation Tower Gypsum
Separator
limestone
H2SO4
Reaction
Air
SO2+CaO CaSO32CaSO3+O2 2CaSO4CaCO3+SO2 CaSO3 + CO2
5 D l h i ti T h l
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5. Desulphurization Technology
5-3 Coke Oven Gas Desulphurization Process
System DeSOx-
chemical
Catalyst Byproduct
Takahax-
Hirohax
NH3 naphtoquinone
salfonic acid soda
(NH4)2SO4
+ H2SO4
Takahax-Reduction
Decomposition
Na2CO3 naphtoquinone
salfonic acid soda
crude S
Fumax-Hemibau NH3 picric acid H2SO4
Stred Ford-
Combax flue gasDe-Sox
Na2CO3
anthoraquinone
sulfonic acid sodametavanadate soda
Tartaric acid soda
gypsum
Diamox-claus NH3 none pure S
Salfiban-claus alkanol amine none pure S
refined
COG
coke oven primary cooler EP
booster De-SOx
(NH4)2SO4saturator
naphthalene
scrubber
final
cooler
benzene
scrubber COG refining process
5 D l h i ti T h l
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5. Desulphurization Technology
5-4 Takahax-Hirohax Process
desulphurized COG
COG
waste gas
waste gas
water
air
air water wastewater
Absorber
EP
Oxidation tower
Service tank Heat exchanger Reaction tower
wastewater
wastewater
ReactionNH3 + H2O NH4OH
NH4OH + H2S NH4HS + H2O
NH4OH + HCN NH4CN + H2O
NH4HS + 1/2O2 NH4OH + SNH4CN + S NH4NCS
Removal rate
S, CN 90~99%
Gas washer
5. Desulphurization Technology
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p gy
5-5 Fumax Process
Absorption
NH3 + H2O NH4OH
NH4OH + H2S NH4HS + H2O
NH4HS + 1/2O2 NH4OH + S
S + O2 SO2
SO2 + 1/2O2 SO3SO3 + H2O H2SO4Regeneration
H2SO4 recovery
COG
Absorber
AIR
Absorber
Mist catcher
NH3 scrubber H2S scrubber
A l k a l i n e s o l .
Regenerator
Evaporator
Picric acid
to H2SO4 plant
CF
Regenerator
Mixing t.
6 NOx Control Technolpgy
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6. NOx Control Technolpgy
6-1-1 NOx Generation
SThermal NOx
r e t e n t i
o n
t i m e
( s )
0 . 0 1
t =
1 0 0
1 0
1
0 . 1
0.6 1.0 1.4 1.810
100
1,000
5,000
N O p p m
Air ratio
N & S Contents in Fuels
0.3~2.60.7~2.2coal
0.2~1.00.6~1.4coke
0.1~3.00.03~0.34crude oil
0.2~0.30.2~0.4C-oil
0.2~0.30.08~0.35B-oil
0.2~0.30.005~0.08 A-oil
0.03~0.50.004~0.006light oil
0.001~0.20.0005~0.01kerosene
1.5~70~9COG-crude0.05~0.70.02~0.5COG-fine
tr tr BFG
tr tr LDG
tr tr LPG, LNG
NFuel
wt%Solid
Liquid
wt%
Gas
g/Nm3
S
JIS K2205 kinematic viscosity (cSt, mm2/s)
C-heavy oil: 50 ~1,000, B-heavy oil: 20~50, A-heavy oil: 20
6 NOx Control Technology
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6. NOx Control Technology
6-1-2 Factors in NOx Generation & Reduction
I m p r o v e
m e n t b y F u
e l
I m p r o
v e m e n t b y
c o m b u s t i o n
Fuel alternation
- Multistage combustion
- Recirculation of exhaust gas- Addition of steam or water
- Low NOx burner
- Change of fuel
heavy oil light oil gas
- Denitrification of COG
- Low air ratio combustion
- Lowering dry hot air temperature
- Changing thermal load
Fuel denitrification
Changing operating conditions
Remodeling combustion system
Causes of generation Reduction methods
N in fuel
O2 con.
Flame temp.
Retentiontime
low N fuel
lower O2
lower
temp.
shorter
retention
6 NOx Control Technology
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6. NOx Control Technology
6-2-1 Fuel Improvement
1. Use of low N and low S fuel ( S N)
2. Denitrif ication of COG N 1~9 g/m3 800~1,000 , 4~6 sec.
6-2-2 Combustion Improvement
1. Low air ratio operation O2 1% NOx 10%2. Multistage combustion 1st stage air ratio; 80~90%
rest air 2nd stage combustion
3. Steam or Water injection flame temp. Nox
no-change in generated calorie
4. Exhaust gas circulation
N O x r e m o v
a l %
Gas circulation %
100
20 F l a m e t e m p .
10 40 1 , 4
0 0
2 , 2 0 0 M=1.0
M=1.2
Injected steam
N O
x p p m
NOx
6 NOx Control Technology Continued from previous slide
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6. NOx Control Technology Continued from previous slide
5. Low- NOx burner
Wide-angle burner tile
Double-stage
combustion burner
Self-circulate
combustion burner
air
oil
gas
primary air secondary air
tile angle
exhaust
gas
fuel ring nozzle
air
circulating gas
ti le angle (degree)
N O x p p m
30 60
primary air ratio
0.81.0
150
100
50 total air ratio : 1.1
oil
COG250
150
200
1.0 4.0
50
75
25
O2 in exhaust gas %
6 NOx Control Technology
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6. NOx Control Technology
6-3 Denitr ification of Exhaust Gas
dry EP
sintering machinecoolingtower
absorptiontower
mist separator
De-SOx wet EP
after burner HEheating
furnace
De-NOxDe-COstack
Sox rem. 90%
Nox rem. 90%
50400
140
De-NOx: Dry Type Selective Contact Reduction using NH36NO + 4NH3 5N2 +6H2O
6NO2 + 8NH3 7N2 +12H2O
7 Environmental Management System(1/2)
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7. Environmental Management System(1/2)
Items to be considered at factory construction & operation
1. Environmental impact assessment
2. Environmental standards & emission standards
3. Planning of plant & air pollution control equipment
4. Operation control & worker training
5. Environmental monitoring
6. Environmental management system
Plan
DoEnforcement & application
Check
Confirmation & collective measures
Plan
Do
Environmental principles Action
Reviewing by plant manager
EMSEMS
Internal inspection
to next stepISO14001
7 Environmental Management System (2/2)
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7. Environmental Management System (2/2)
Measurement Items
P o l l u t a n t s
Emission Standard
dust
sulfur oxide
nitrogen oxide
Cd, its compounds
Cl, HCl
F, HF, SinF2n+2Pb, its compounds
Suspended particle matter
SO2
(sulfur oxide)
NO2 (nitrogen oxide)
COPhotochemical oxidant
EQS
Telemeter System
Q
SOx
NOx
Q
SOx
NOx
automatic measurements site center administration center
8. Resources Saving
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8. Resources Saving
Dust Generation & Util ization
Dust generation in Integrated Iron Works: 4.9% of crude steel
Ingredient of Dust: Iron Oxide, Limestone, etc.
Utilization: Raw Material forSintering, Zn, ZnCO3, Neutralizing wastewater, BF
Process Dry Dust
Collector
Wet Dust
Collector
Total
Material / PigIron
111,000 38,000 149,000 (61%)
Steel 33,000 60,000 93,000 (38%)
Rolling 2,700 300 3,000 (1%)
Total 146,700
(60%)
98,300
(40%)
245,000
(100%)
Dust Generation at 3 mil lion-ton Crude Steel Production (t / y)
9. Energy Saving
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gy g
Energy source ratio (%)
electricity
41.1
7.6
25.3
14.5
11.5
coal
coke
others
heavy oil
Integrated Steel Production
7.9
51.734.5
4.4 1.5
electricityfuel oil
LPG
light oil
others
Non-Integrated Steel Production
Energy saving Method
high efficient equipment & improving operation
reducing the number of unit operations
& changing to continuous processwaste heat recovery