air pollution control technology in steel industry china 2005

8/18/2019 Air Pollution Control Technology in Steel Industry China 2005

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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


2/31

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


3/31

Raw materials yard

Coking

BF

COG refinerySteel manufacturing

processes

Steel mill l ives close together

with neighboring people

(Kobe Steel Kakogawa Plant)


4/31

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


5/31

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


6/31

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


7/31


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


8/31


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


9/31


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


10/31


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


11/31


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


12/31


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


13/31

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


14/31


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


15/31


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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4-4 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


17/31


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


18/31

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


19/31


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


20/31


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


21/31


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



22/31

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


23/31

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


24/31

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



25/31


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


26/31

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 %



27/31


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)


28/31

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)


29/31

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


30/31

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


31/31

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

air pollution control technology in steel industry china 2005

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