Mercury Sorption and Mercury Oxidation

by Chlorine and Bromine at SCR DeNOx Catalysts

Part B: Sorption

Prof. Dr.-Ing. Bernhard W. Vosteen*, Vosteen Consulting GmbH, Cologne, GER

Dipl.-Ing. Sandra Straube, MLU Halle-Wittenberg, GER

Prof. Dr.-Ing. habil. Heinz Köser, MLU Halle-Wittenberg, GER

*) corresponding author

email: info@vosteen-consulting.de

phone: +49 221 680 098 22

9th Annual EPA, DOE, EPRI, EEI Conference onClean Air, Mercury, Global Warming & Renewable Energy

Westin La Paloma Resort, Tucson, Arizona

Track B7, No 6 – Mercury – Wednesday 01/25/2006

2

VosCons

Vosteen Consulting GmbH

(Prof. Vosteen, Cologne, GER)

Bayer Industry Services GmbH & Co. oHG

(Leverkusen, GER)

Martin-Luther-University Halle-Wittenberg

Institute for Environmental Engineering

(Prof. Köser, Merseburg, GER)

Martin-Luther-Universität

Halle-Wittenberg

Vosteen Consulting GmbH

Process developement since 2000

3

VosCons

Vosteen Consulting GmbH Vosteen Consulting GmbH , Cologne,

ALSTOM-Environmental Control Systems,Knoxville/TN, USA,

exclusive licensee for North America

Trademark of ALSTOM Power Inc.:KNXTM Coal Additives and Systems

Electric Power Research Institute, PaloAlto/CA, USA,

holding a research grant

for demonstration test runs

Southern Company Services, Inc.

Birmingham/AL, USA

US-EPRI

Cooperations in USA and Canada since 2005

SCS

4

VosCons

Table of Contents:

Basic aspects of bromine enhanced mercury oxidation

at SCR DeNOx catalysts

Part B:

Mercury Sorption at SCR DeNOx Catalysts (see EUEC workshop No 13 together with ALSTOM Power Inc.)

1. Mercury Retention in industrial tail-end-SCRs (ca. 20 tons catalyst)

2. Adsorption of Hgel and Hg2+ at SCR catalysts of different

V2O5-content in humid air , heats of adsorption

3. Enhanced desorption/eluation of adsorbed mercury as Hgox

(Adsorptive competition between HX and Hgox, displacement of

oxidised mercury by HX/X2)

5

VosCons

1. Mercury Retention in industrial tail-end-SCRs

(ca. 20 tons catalyst)

6

VosCons

Up and Down Stream Sections of a SCR DeNOx catalyst bed

axis z

Up Stream Section

(near entrance)

Down Stream Section

(near exit)

DeNOx-active part

NH3 is reducing Hgox and displacing Hgel

in conjunction with NO, SO2,…

(chemically enhanced desorption of Hgel)

see e.g. Thorwarth et. al.,

Clearwater Coal Conference (2005)

HgOx-active part

Hgel and Hgox are adsorbed

HX/X2 is oxidizing Hgel and displacing Hgox

(chemically enhanced desorption of Hgox)

see e.g. Vosteen et al.,

VGBPowerTech (2003)

Hgel

Hgox

Low AV [Nm /(m hr) = m/hr] or corresponding low SV [Nm /(m hr) = 1/hr]

do elongate the extension of the HgOx-active part

7

VosCons

Instationary estate of SCR DeNOx catalyst bed:

The catalyst‘s mercury load [mg Hgtotal/kg]

is increasing or decreasing all the time

The mass fluxes of adsorbing and desorbing mercury

are not symmetrical and not simultaneous

(ad-/desorption phenomena become visible by separation as in Gaschromatography)

Dosierbehälter mit

HCl- stabilisierter

HgCl2- Lösung

Schlauchpumpe

zum Dosieren der

HgCl2- Lösung

wassergekühlte

Dosierlanze am

Kopf der NBK

dosing

pump

spraying

nozzle

HgCl2container

Hgmet bomb

Continuous spiking Discontinuous spiking

8

VosCons

In Plant Research in 2000/2001

at Hazardous Waste Combustion Plants in Leverkusen, Dormagen and Uerdingen(Germany) of similar design with waste heat recovery boiler, multistage wet scrubber,wet ESP, tail-end SCR-DeNOx

1

8 9

10

11

12

2

3

4 5

7

16

13

1415

176

Fig. 1

Hg-spiking

(continuous)

Hg-spiking

(continuous)

Hg-CEMs

Hg-spiking

(discontinuous)

Quench

Hg-spiking

(continous)

Hg-spiking

(continuous)

Hg-CEMs Hg-SCEM

Hg-spiking

(discontinuous)

Quench

1

8 9

10

11

12

2

3

4 5

7

16

13

1415

176

Fig. 1

1

8 9

10

11

12

2

3

4 5

7

16

13

1415

176

Fig. 1

Hg-spiking

(continuous)

Hg-spiking

(continuous)

Hg-CEMs

Hg-spiking

(discontinuous)

Quench

Hg-spiking

(continous)

Hg-spiking

(continuous)

Hg-CEMs Hg-SCEM

Hg-spiking

(discontinuous)

Quench

9

VosCons

Hgtotal- and Hgmet-CEMs at the SCR-measuring points 16, 18, 19, 20

Hgtotal- SCEM at the stack-measuring point 17

AmmoniakwasserT= 300 °C

Erdgas und

Verbrennungsluft

RG zum gummierten Kamin

T< 100 °C

T = 60 - 70 °C

R G aus VA1

Messstelle nach

WT (nach SCR)

Messstelle

nach WT/ vor Kat

Messstelle

nach KEGR

Messstelle

nach Kat/ vor WT

T= 110 °C

T= 141 °C

T= 270 °C

Messstelle

am Kamin (22 m )

RG aus VA2

T= 60 - 70 °C

RG aus VA3 und VA4

T< 100 °C

18

16

19

20

17

AmmoniakwasserT= 300 °C

Erdgas und

Verbrennungsluft

RG zum gummierten Kamin

T< 100 °C

T = 60 - 70 °C

R G aus VA1

Messstelle nach

WT (nach SCR)

Messstelle

nach WT/ vor Kat

Messstelle

nach KEGR

Messstelle

nach Kat/ vor WT

T= 110 °C

T= 141 °C

T= 270 °C

Messstelle

am Kamin (22 m )

RG aus VA2

T= 60 - 70 °C

RG aus VA3 und VA4

T< 100 °C

18

16

19

20

17

NH3 aq

10

VosCons

Lower SCR heat exchanger, PTFE Upper SCR heat exchanger, steel

11

VosCons

BASF Honeycomb SCR-catalyst(TiO2, WO3 and V2O5 as active component)

Total mass of catalyst: 19,242 kg (two beds)

working temperature of 300 °C

gas residence time at 300 °C:

1 sec (half load)

or

0,5 sec (full load)

12

VosCons

0

200

400

600

800

1000

1200

1400

1600

1800

2000

2200

2400

480 495 510 525 540 555 570 585 600 615 630 645 660

lfd. Versuchszeit [min]

Hg

me

t =

Hg

ges vo

r S

CR

.

Hg

io

n =

Hg

ges n

ac

h S

CR

[g

/Nm

? t

r.]

Hggges = Hgmet nach Wäsche / vor SCR bei Einwurf von vier kleinen Hg-Bomben zu je 26 g

Hgges = Hgion nach SCR

Hgmet nach SCR (annähernd Null)

Hgges (= Hgion)

nach Tail-End-SCR

Hgges (= Hgmet)

nach Wäsche,

d.h. vor Tail-End-SCR

Hgmet

nach Tail-End-SCR

Hgmet behind

tail-end DeNOx-SCR

Hgtotal (= Hgion) behind

tail-end DeNOx-SCR

Hgtotal (= Hgmet-peaks) in front of

tail-end DeNOx-SCR

running time [min] since 00:00 a.m. on June 15th, 2000

Hg

[g /

Nm

? d

ry]

Adsorption of Hgmet

No desorption of Hgmet

chemically enhanced

desorption of only Hgox

13

VosCons

0

2

4

6

8

10

0 100 200 300 400 500

Hgges im Reingas nach SCR [ g/m? i. N. tr.]

Hg

-Bela

du

ng

der

SC

R [

g H

g]

Hg-Sorptionsisotherme

der SCR mit 19.242 kg

Katalysator-Bettmasse

(nach Vosteen)

Ermittelbar aus Hg-Entladung ("Desorptionsisotherme")

bzw. Hg-Beladung ("Adsorptionsisotherme")

Hgges ( = Hgion)-Gehalt

im entstickten Reingas nach SCR [ g/m? i N. tr.]

SC

R-

Be

lad

un

g [

g H

g]

als

ein

ge

sp

eic

he

rte

Hg

-Me

ng

e

Hgto

tal-load

of ta

il-end-S

CR

[g]

Hgtotal = Hg2+ in cleaned flue gas behind tail-end-SCR

[ g/Nm? dry]

Hg-Eluation-Curve

(19.242 kg catalyst)

14

VosCons

0,01

0,10

1,00

820 830 840 850 860 870 880

Zeit [min] ab 00:00 Uhr am 15. 6. 2000

cH

g (

t) /

cH

g(t

o =

820m

in)

Berichtszeitraum

2000-06-15 13:40 Uhr -

2000-06-15 14:40 Uhr

Hgion-Eluation folgt

einer halblogarithmischen Geraden

log [cHg(t) / cHg(to=820)] = 1 - 1,0286 * t/min

Hg-Eluation-Curve is described by

Running time [min] since 00:00 on June 15, 2000

15

VosCons

0,01

0,10

1,00

10,00

820 880 940 1000 1060 1120 1180 1240 1300 1360 1420 1480

Zeit [min] ab 00:00 Uhr am 15. 6. 2000

cH

g (

t) /

cH

g(t

0 =

820 m

in)

Berichtszeitraum

2000-06-15 13:40 Uhr -

2000-06-16 00:50 Uhr

Hgion-Eluation beschleunigt

durch vermehrtes Cl2-

Spurenangebot

i T il E d SCR !

Hgion-Eluation limitiert durch

begrenztes Cl2-Spurenangebot

in Tail-End-SCR ?

(Z h lt

Bezugspunkt bei

t 0 = 820 min

Running time [min] since 00:00 on June 15, 2000

Mercury eluation rate constant

because HCl/Cl2-content of the

flue gas being very low

Mercury eluation rate increasing

with increasing HCl/Cl2-content

in flue gas

16

VosCons

First Industrial Demonstration in 2002 (2 x 5 days testing)

PC-fired Wet Bottom Boiler (100 MWtherm; 140,000 Nm /h dry)

of BAYER AG in Uerdingen (Germany),

ESP, limestone based wet FGD, tail end DeNOx-SCR

Messung

von

Hgges und Hgmet

Messung

von

Hgges und Hgmet

Eindosierung

von HgCl2 und NaCl

Spiking with

HgCl2 and NaBr

CEMs for

Hgtotal and Hgmet

CEMs for

Hgtotal

bituminous

coal

bituminous

coal

air

air

FGD

17

VosCons

Hg-Gehalte im Rauchgas vor und nach SCR bei unterschiedlichen

Br(ges)-Niveaus im Rohgas beim Versuch vom 14.08.2002

0

5

10

15

20

25

30

10:00 11:00 12:00 13:00 14:00 15:00 16:00 17:00 18:00 19:00 20:00

Zeit [hh:mm]

Hg

(ges)-

Geh

alt

nach

RE

A/v

or

SC

R [

g/N

m3],

Hg

(ges)-

Geh

alt

nach

SC

R/a

m K

am

in [

g/N

m3]

0

20

40

60

80

100

120

Br(

ges)-

Geh

alt

im

Ro

hg

as ü

ber

NaB

r-

Do

sie

run

g [

mg

/Nm

3]

Hg(ges)-Gehalt nach REA/vor SCR Hg(ges)-Gehalt nach SCR (am Kamin) Br(ges)-Gehalt über NaBr-Dosierung

2002-08-14 10:00

bis

2002-08-14 20:00

running time on August 14th, 2002

Hgtotal in flue gas

behind FGD

Hgtotal in flue gas

behind tail end SCR

Brtotal in boiler raw gas

Brtotal

[mg/Nm? dry]

Hgtotal

[ g/Nm? dry]

Tiny bromine concentrations (< 1 mg/Nm dry)were enhancing Hg-elution out of tail-end SCR

18

VosCons

2. Adsorption of Hgel and Hg2+ at SCR catalysts of different

V2O5-content in humid air, heats of adsorption

19

VosCons

H2O/HCl/HBr

HgCl2

20

VosCons

commercial SCR-DeNOx-catalysts

0 - 0,53 - 2,5 - 4,5 Ma.-% V2O5

ca. 15 g … 31 g

4 x 4 channels

6,5 … 13 cm long

2 x 0,5 g

Einsatz für Glasringspaltreaktor

0 - 2000 g Hg/Nm

Laboratory Research on mercury oxidation at SCR-DeNOx catalysts

Duration of laboratory test runs:

24 hours up to some days

Duration of laboratory test runs:

Some hours up to one day

crashed

21

VosCons

Chemical and physical properties of the investigated SCR-DeNOx catalysts

50n.d.*n.d.*BET surface (m /g)

780760760Specific geometric surface area (m /m )

3.543.53.5Free channel width (mm)

4.34.24.2Pitch (mm)

6.87.98.7WO3 content (wt.-%)

4.52.50.53V2O5 content (wt.-%)

C 4.5C 2.5C 0

fresh catalyst

* not determined

22

VosCons

Hovacal-Beladung eines Katalysators mit 4,5 Ma.-%

V2O5 bei 300 °C (Versuch vom 24. 4. 2003)

0

10

20

30

40

50

0 4 8 12 16 20 24lfd. Zeit / h

Hg ges

Hg ox

Hgges

-Beladung

von 47,8 mg/kg (keine Sättigung),

erreicht mit 140 g Hgel

/Nm?

+ 56 g Hgox

/Nm? im Rohgas

Hgox

-Endbeladung

von ca. 7 mg/kg (Sättigung),

erreicht mit

56 g Hgox

/Nm? im Rohgas

Hg

-Bel

adu

ng

des

Kat

aly

sato

rs /

mg

/kg

Running time [h] at April 24, 2003

Hg-l

oad

of

cata

lyst

[mg

/kg

] Hgtot

Hgox

Mixed loading of a honeycomb catalst with 4.5 weight-% V2O5 at 300 °C

with 140 g Hgtot/Nm? in humid air

HgCl2/H2O were evaporated in a HOVACAL-evaporator, ca. 15 % reduced to Hgel in front of catalyst

Equilibrium loading within 24 hours not yet reached

either by Hgtot = Hgel + Hgox nor only by Hgox

23

VosCons

Hovacal-Beladung eines V2O5-freien Katalysators bei

300 °C (Versuch vom 6. 5. 2003 mit feuchter Luft)

0

10

20

30

40

50

0 5 10 15 20 25 30

lfd. Zeit / h

Hg ges

Hg ox

Hgges

-Endbeladung

von 7 mg/kg (Sättigung),

erreicht mit

150 g Hgel

/Nm? + 43 g Hgox

/Nm?

im Rohgas

Hgox

-Endbeladung

von ca.0,9 mg/kg (Sättigung),

erreicht mit

43 g Hgox

/Nm?

im Rohgas

Hg-B

elad

ung d

es K

atal

ysa

tors

/

mg

/kg

Running time [h] at May 6, 2003

Hg

-load

of

cata

lyst

[mg/k

g]

Hgtot

Hgox

Mixed loading of a honeycomb catalst with no V2O5 at 300 °C

with 140 g Hgtot/Nm? in humid air

HgCl2/H2O were evaporated in a HOVACAL-evaporator, ca. 15 % reduced to Hgel in front of catalyst

Equilibrium loading within 24 hours not yet reached,

either by Hgtot = Hgel + Hgox nor only by Hgox

24

VosCons

H gg e s

-A d s o r p t io n d u r c h H o v a c a l-B e la d u n g b e i 3 0 0 ° C

a n v ie r K a ta ly s a to r e n (V e r s u c h e v o m A p r i l/M a i 2 0 0 3 )

0

2 5

5 0

7 5

1 0 0

1 2 5

1 5 0

1 7 5

2 0 0

0 5 1 0 1 5 2 0 2 5 3 0 3 5 4 0 4 5 5 0

s p e z . H gg e s

-B e la d u n g d e s K a ta ly s a to r s / m g /k g

0 M a .-% V 2 O 5

4 ,5 M a .-% V 2 O 5

2 ,5 M a .-% V 2 O 5

1 ,5 M a .-% V 2 O 5

H gg e s

im R o hg a s

Hg

ges-R

ein

gas

ko

nze

ntr

atio

n n

ach

Kat

aly

sato

r /

g/N

m?

Hgtot-load of honeycomb catalyst [mg/kg]

Hgto

t-c

onte

nt

in g

as b

ehin

dca

taly

st

[g

/Nm

? dry

]

Comparison of the mixed loading of a honeycomb catalst with 0 …4.5 weight-% V2O5 at 300 °C

193 g Hgtot/Nm? in humid air

HgCl2/H2O were evaporated in a HOVACAL-evaporator, ca. 15 % reduced to Hgel in front of catalyst

In case of 4.5 weight-% V2O5

the break through was not even reached after 2 days!

Hgtotin front of cat

4.5 % V2O5

2.5% V2O5

1.5 % V2O5

0 % V2O5

25

VosCons

Hg-Adsorption Isothermes of Hgel and Hgox at a SCR-catalyst

290 °C, crashed catalyst with 2.5 weight-% V2O5 in humid air, 15 vol.-% H2O

Hgel

Hgox

(HgCl2)

0

500

1000

1500

2000

2500

3000

3500

4000

0 0,01 0,02 0,03 0,04 0,05 0,06 0,07

Partialdruck Gasphasen-Hg / Pa

Hg

-Bel

ad

un

g /

mg

Hg

/kg

Ka

t.

0 500 1000 1500 2000 2500 3000

Hg-Gasphasenkonzentration / g/Nm?

290°C

290°C

Hg-concentration in gas phase [ g/Nm? dry]

Hg-l

oa

do

f ca

taly

st[m

g/k

g]

Hg-partial pressure [P]

26

VosCons

Hg-Adsorptionsisobaren bei 160 g Hg/Nm?

eines SCR-Katalysators (2,5 Ma.-% V2O5) in Feuchtluft (15 Vol.-% H2O)

306

34,2109

2276

3,50

200

400

600

800

1000

1200

1400

1600

1800

2000

2200

2400

2600

2800

3000

0 50 100 150 200 250 300 350 400 450

Temperatur /°C

Hg

-Be

lad

un

g d

es

SC

R-K

ata

lys

ato

rs

.

in

mg

/kg

160 g Hg/Nm? als Hgel in reinerFeuchtluft

160 g Hg/Nm? als HgCl2 inreiner Feuchtluft

160 g Hg/Nm? als Hgel inFeuchtluft mit 5 mg HCl/Nm?

Exponentiell (160 g Hg/Nm? alsHgel in reiner Feuchtluft)

Exponentiell (160 g Hg/Nm? alsHgCl2 in reiner Feuchtluft)

160 g Hg/Nm? in Gasphase,

überwiegend als Hgel

160 g Hg/Nm? in Gasphase

überwiegend als HgCl2

Zugabe von

5000 g HCl/Nm?

160 g Hgel/Nm? in humid air

160 g Hg2+/Nm? (as HgCl2)

in humid air

160 g Hgel/Nm? in humid air

with 5 mg HCl/Nm?

Hgel

Hgox (HgCl2)

Hg-l

oa

do

f ca

taly

st[m

g/k

g]

temperature [°C]

Hg-Adsorption Isobares of Hgel and Hgox (HgCl2) at a SCR-catalyst

160 g Hg/Nm dry, crashed catalyst with 2.5 weight-% V2O5 in humid air, 15 vol.-% H2O

27

VosCons

Hg-Adsorptionsisobaren bei 160 g Hg/Nm?

eines SCR-Katalysators (2,5 Ma.-% V2O5) in Feuchtluft (15 Vol.-% H2O)

10

100

1000

10000

1 1,1 1,2 1,3 1,4 1,5 1,6 1,7 1,8 1,9 2 2,1 2,2 2,3 2,4

10? K/ T

Hg

-Be

lad

un

g /

.

mg

/kg

160 g Hg/Nm? als Hgel in reiner

Feuchtluft

160 g Hg/Nm? als HgCl2 inreiner Feuchtluft

Exponentiell (160 g Hg/Nm? alsHgel in reiner Feuchtluft)

Exponentiell (160 g Hg/Nm? alsHgCl2 in reiner Feuchtluft)

160 g Hg/Nm? in Gasphase,

überwiegend als HgCl2

160 g Hg/Nm? in Gasphase

überwiegend als Hgel

Hgox (HgCl2)

Hgel

Hg-load

[mg

/kg

]

evaluation based on the

different slopes:

Heats of adsorption

in pure humid air

17 kJ/mol Hgox

(as HgCl2)

61 kJ/mol Hgel

Hg-Adsorption Isobares of Hgel and Hgox (HgCl2) at a SCR-catalyst

160 g Hg/Nm dry, crashed catalyst with 2.5 weight-% V2O5 in humid air, 15 vol.-% H2O

28

VosCons

3. Enhanced desorption/eluation of adsorbed mercury

as Hgox

29

VosCons

0

5

10

15

20

25

30

35

0 2 4 6 8 10 12 14 16 18 20 22

lfd. Zeit / h

Zeitlicher Verlauf des Rückgangs der Hg-Beladung des

Katalysators mit 1,5 Ma.-%V2O5 bei 300°C (Versuch v. 17.4.2003)

in 2 Entladungsschritten (1. feuchte Luft, 2. HCl-Zugabe)H

g-B

elad

ung d

es K

atal

ysa

tors

/

mg

/kg

Hgox

Hgges

15 Vol.-% H2O

100 mg/Nm? HCl +

15 Vol.-% H2O

Hg-l

oad

of

the

cata

lyst

[mg

/kg

]

Running time [h] of discharge

Hgtot

humid air only

Hg-elution at 300 °C out of the catalyst with 1.5 % V2O5

(Hg-loading was done on April 17, 2003)

1st elution step: humid air 2nd elution step: humid air + HCl/Cl2

HCl is displacing („kicking off“) Hgox

30

VosCons

Zeitlicher Verlauf der Hg-Desorption des Katalysators mit

4,5 Ma.-% V2O5 bei 300 °C (Versuch vom 25. 4. 2003) in

2 Entladungsschritten (1. feuchte Luft, 2. HCl-Zugabe)

0

500

1000

1500

2000

2500

3000

3500

4000

4500

0 3 6 9 12lfd. Zeit / h

Hgel

= 0

100 mg/Nm? HCl +

15 Vol.-% H2O

Hgges

= Hgox

Hg

-Rei

ng

ask

on

zen

trat

ion

nac

h K

atal

ysa

tor

/

g/N

m?

15 Vol.-% H2O

Hgges

= Hgel

Hgox

< 10 g/Nm?

Hgto

tin

cle

an g

as b

ehin

dca

taly

st

[mg

/kg

]

Running time [h] of discharge

Hgtot = mainly Hgel

Hgox < 10 %

humid air only

Hg-elution at 300 °C out of the catalyst with 4.5 % V2O5

(Hg-loading was done on April 24, 2003)

1st elution step: humid air 2nd elution step: humid air + HCl/Cl2

Hgtot = Hgox

Hgel = 0 %

31

VosCons

0

50

100

150

200

780 785 790 795 800 805 810

Zeit [min] ab 00:00 Uhr am 8. 6. 2000

Hg

ges (=

Hg

ion)

na

ch

SC

R-K

at/

vo

r W

T

Hg

ges (

= H

gm

et) n

ach

WT

(am

SC

R-A

ustr

itt)

[g

/m?

i.

N.

tr.]

-500

0

500

1000

1500

Hgges = Hgion nach Kat/vor WT

Hgges = Hgion nach WT am Austritt aus der SCR

SO2 im Kesselrohgas der Anlage A vor Wäsche

Berichtszeitraum

2000-06-08 13:00 Uhr -

2000-06-08 13:30 Uhr

S

O2 v

or

Wäsch

e [

mg

/Nm

?]

Verweilzeit im WT

Peakverbreiterung und -abflachung im WT

SO2 im Rohgas

vor Wäsche

Hgges (= Hgmet)

nach Kat/vor WTHgges (= Hgmet)

nach WT/SCR

SO2 boiler

raw gasHgtotal (= Hg2+ ) behind

SCR catalyst bed or at SCR exit.

Time [min] since 00:00 at June 8th, 2000

Hgtotal (= Hg2+) in

gas behind SCR

[ g Hg / Nm? dry]

SO2 boiler raw gas

[mg SO2 / Nm? dry]

residence time in

heat exchanger

Peak broadening in heat exchanger

0

50

100

150

200

780 785 790 795 800 805 810

Zeit [min] ab 00:00 Uhr am 8. 6. 2000

Hg

ges (=

Hg

ion)

na

ch

SC

R-K

at/

vo

r W

T

Hg

ges (

= H

gm

et) n

ach

WT

(am

SC

R-A

ustr

itt)

[g

/m?

i.

N.

tr.]

-500

0

500

1000

1500

Hgges = Hgion nach Kat/vor WT

Hgges = Hgion nach WT am Austritt aus der SCR

SO2 im Kesselrohgas der Anlage A vor Wäsche

Berichtszeitraum

2000-06-08 13:00 Uhr -

2000-06-08 13:30 Uhr

S

O2 v

or

Wäsch

e [

mg

/Nm

?]

Verweilzeit im WT

Peakverbreiterung und -abflachung im WT

SO2 im Rohgas

vor Wäsche

Hgges (= Hgmet)

nach Kat/vor WTHgges (= Hgmet)

nach WT/SCR

SO2 boiler

raw gasHgtotal (= Hg2+ ) behind

SCR catalyst bed or at SCR exit.

Time [min] since 00:00 at June 8th, 2000

Hgtotal (= Hg2+) in

gas behind SCR

[ g Hg / Nm? dry]

SO2 boiler raw gas

[mg SO2 / Nm? dry]

residence time in

heat exchanger

Peak broadening in heat exchanger

SO2 boiler

raw gasHgtotal (= Hg2+ ) behind

SCR catalyst bed or at SCR exit.

Time [min] since 00:00 at June 8th, 2000

Hgtotal (= Hg2+) in

gas behind SCR

[ g Hg / Nm? dry]

SO2 boiler raw gas

[mg SO2 / Nm? dry]

residence time in

heat exchanger

Peak broadening in heat exchanger

Artificial oszillations of SO2 are inducing countercurrent oscillations of Hgion at SCR exit

because SO2 is suppressing NaOCl in scrubber and therewith Cl2 behind scrubber

(Vosteen et al., Air Quality Conference (IV), Arlington, Washington D.C., 2003)

32

VosCons

Up and Down Stream Sections of a SCR DeNOx catalyst bed

axis z

Up Stream Section

(near entrance)

Down Stream Section

(near exit)

DeNOx-active part

NH3 is reducing Hgox and displacing Hgel

in conjunction with NO, SO2,…

(chemically enhanced desorption of Hgel)

see e.g. Thorwarth et. al.,

Clearwater Coal Conference (2005)

HgOx-active part

Hgel and Hgox are adsorbed

HX/X2 is oxidizing Hgel and displacing Hgox

(chemically enhanced desorption of Hgox)

see e.g. Vosteen et al.,

VGBPowerTech (2003)

Hgel

Hgox

Low AV [Nm /(m hr) = m/hr] or corresponding low SV [Nm /(m hr) = 1/hr]

do elongate the extension of the HgOx-active part

33

VosCons

Conclusionssee corresponding part A of this paper (track B5 No4 )

OutlookIn summer 2006 a full scale demonstration of bromine enhanced mercury

oxidation will be performed at a coal-fired 500 MWe-unit with SCR

34

VosCons

Thanks for Your attention

Acknowledgement

The authors and mainly Prof. Vosteen are very thankful to many of his former colleagues with

Bayer Industry Services GmbH Co. oHG, Leverkusen (Germany).

Prof. Köser and Dipl.-Ing. Sandra Straube have to thank for funding by the „Graduierten-

förderung des Landes Sachsen-Anhalt“ and the „Max-Buchner-Forschungsstiftung“.

Vosteen Consulting GmbH