Steag Group

Steag’s Long-Term SCR 

Operating Experience a
Operation & 

Maintenance

Power Generation 

and District Heating

Engineering and 

IT Solutions

Steag Group Facts:• Steag is a wholly owned subsidiary o

largest bituminous coal mining comp

• Steag is Europe‘s second largest pow

bituminous coal.

• Steag owns and operates more than 1

and steam generating capacity.

• In 2004 Steag:

• had more than 5,000 employees w• had revenues of more than $ 6 bil• operated 28 electric generating un

• had 3 electric generating units un• operated 9 waste-to-energy plants • operated 20 electric generating un

• For more info go to www.steag.com.

Steag Group
Steag‘s 

Power Plants

Bexbach775 MW

Fe50

Wa6075CO

Lünen500 MW

Voerde2,220 MW

Bergkamen750 MW

Germany

Termopaipa,Columbia165 MW

Iskenderun,Turkey1.320 MW

Leuna158 MWel + eq.

Cologne-Godorf215 MWel + eq.

International Mindanao,

Philippines260 MWCOD 2006
Steag’s Various SCR Arrangemen

Boiler NH3

SCR

Air Heater

Air

ESP

FGD ESP

Air Air Heater

Regenerative Gas Heat Exc

Boiler

ESP

Air

Air Heater

Steam

NH3

SCR

Regenerative 

Gas-Gas Heat 

Exchanger 

Steam 

Reheater

Boiler

ESP 

FGD

Steag‘s

SCR Arrangements
Herne Cogeneration Plant:

- Units 1 & 2 - 150 MW electricity each.- Unit 3 - 300 MW electricity.- Both PC U-fired, wet bottom boilers.- Tail-end SCRs, honeycomb catalyst.- Unit 4 - 385 MW electricity.

- 550 MW district heat.

- PC wall-fired, dry bottom boiler.- High-dust SCR system, plate catalyst.- Bone meal, waste bituminous coal, 

ash > 40%, sulfur < 1.5%. 

- Wet CaO/CaCO

3 forced oxidation 

FGD system producing wall board quality gypsum, flue gas reheat via rotary gas/gas heat exchanger.

- Operator: Steag- Owner: Steag- Power Purchaser: RWE

Steag District Heat 

Herne 

Cogeneration Plant
Herne Unit 3

Tail-End SCR

0 20000 40000 60000 80000 10

SCR operating hours

DeNOx potential P

SCR Commissioning in 1988:- 1 1⁄2 layers of honeycomb catalyst (550 m- 2 1⁄2 spare layers (still empty).Operation during the past 110,000 operatiextremely uneventful. No catalyst addition Total catalyst replacement cost = 0.9% pe

Herne 3
Herne Unit 4

High-Dust SCR

0 20000 40000 60000 80000 

SCR operation hours

DeNOx potential P

SCR Commissioning in 1989:- 2 layers of honeycomb catalyst (installe- 2 spare layers (layers 2 and 4).Severe erosion problems resulting from wreplacement of both honeycomb layers in plate catalyst has been used. Operating h

Herne 4
4.2

4.1

3.2 D D D D 

C C C C 

HC 2 3.1

2.2 F (new) F 2.1 E (new) B G (new) 

1.2 B B

A E E 

HC 1 1.1

layer

0 (plate) 16,500 31,000 45,000 

Initial 

(hc)

A

Removal 

of honeycombs; 

addition 

of plate 

layers.

Addition 

of new 

half plate 

layer E.

Removal of 

layer A to 

regeneration, 

addition of 

new plate 

layer F.

Removal of 

layer B to 

regeneration, 

addition of 

new plate 

layer G.

Removal o

layer C to 

disposal, 

addition o

new plate

layer H.

Herne Unit 4

High-Dust SCR

Herne 4 Catalyst Exchange Logbook
Comments and Costs:

- Honeycomb was found to be unable to 

from the high ash waste coal burned.

- Initial fill of 4 half plate layers was set to 

the initial cost. 

- Total catalyst exchange cost during the 

operating hours was found to be:

- For catalyst replacement 9 (4 initial 

new half layers (= 225% of initial cosreplacement layer (= 12% of initial c

- For field labor cost for the installatio

the removal of 5 half layers was fouinitial catalyst cost = 110%.

- Total catalyst replacement costs = 347% 

cost per 1,000 operating hours.

-2-

Herne Unit 4

High-Dust SCR
Voerde Power Station:

- Units 1 & 2 – both 350 MW PC U-fired, w

- Waste bituminous coal, ash > 40%, sulfu- Both tail-end SCR systems, honeycomb - Units 3 & 4 – both 760 MW PC wall-fired

- World market bituminous 

coal, ash < 15%, 

sulfur < 1.5%.

- Both high-dust SCR 

systems, honeycomb and plate catalyst mixed.

- Wet CaCO3 forced oxidation 

FGD system producing wall board quality gypsum, no 

flue gas reheat, wet stack.

- Operator: Steag- Owner: Steag 75%

RWE 25%

- Power Purchaser: RWE

Voerde

Power Station
Voerde Unit 4

High-Dust SCR

0 20000 40000 60000 80000 

SCR operating hours

DeNOx potential P

SCR Commissioning in 1989:- 3 layers of honeycomb catalyst (installe- 1 spare layer (layer 4).LPA catalyst pluggage problems appeare1996. After installation of Steag’s LPA scproblems with LPA intrusion into the SCR 

Voerde 4
4.2

4.1

B 

3.2 C (hc) C C B (reg) 

3.1

A 

2.2 B (hc) B A (reg) A 2.1

1.2 E E C (reg) 

D (pl) D A (hc) 1.1

layer

40,000 48,000 49,000 75,000 

Initial 

0

D

Removal of layer A 

(plugged) to 

regeneration, addition 

of regenerated plates 

from Herne 4 and new 

plate layers D and E.

Removal of 

layer B to 

regeneration, 

addition of 

regenerated 

layer A.

Removal of 

layer C to 

regeneration, 

addition of 

regenerated 

layer B.

Removal 

layers D, 

regenerat

addition 

regenera

layer C

Voerde Unit 4

High-Dust SCR

E (pl)

Voerde 4 Catalyst Exchange Logbook
Voerde Unit 4

High-Dust SCR

Comments and Costs:- Initial fill of 3 honeycomb layers was se

of the initial cost.

- Total catalyst exchange cost during the 

operating hours was found to be:

- For catalyst replacement 5 (3 initial, 

honeycomb replacement) new layer

cost) plus 4 regenerated honeycom(= 66% of initial cost).

- For field labor cost for the removal 

layers was found to be 6 x 10% of in

60%.

- Total catalyst replacement costs = 293% 

cost per 1,000 operating hours.

- Note that 2 catalyst exchanges were ca

pluggage and not by normal catalyst de
Walsum Cogeneration Plant:

- Unit 7 - 150 MW PC U-fired, wet bottom b

- Low dust SCR system, honeycomb cata- Unit 9 - 450 MW PC tangentially-fired, dr- High dust SCR system, plate catalyst. - Bituminous waste coal, 

ash > 40%, sulfur < 1.5% plus sewage sludge.

- Wet CaO/CaCO

3 forced 

oxidation FGD systems producing wall board. quality gypsum, flue gas 

reheat via gas/gas reheater.

- Operator: Steag- Owner: Steag- Power Purchaser: RWE

EnBW

Walsum

Cogeneration Plant
Walsum Unit 9

High-Dust SCR

0 20000 40000 60000 80000 100000 1

SCR operation hours

DeNOx potential P

SCR Commissioning in 1988:- 4 half layers of plate catalyst (installed i- 2 spare half layers (layer 1).Severe erosion resulting from the very hi40%) of the waste coal burned demanded catalyst from initial commissioning on. H

Walsum 9
D

Walsum Unit 9High-Dust SCR

3.2 D D D D 

3.1 C C C C C 2.2 B B B B B 2.1 A A A A A 

1.2 G (used) H (used) H J (new) 1.1 I (new) I 

layer

31,700 51,500 83,500 96,700 

Initial

0

G

Addition 

of used 

layer G 

from 

Walsum

Unit 7.

Addition 

of used 

layer H 

from 

Walsum

Unit 7.

Removal of 

layer G to 

regeneration, 

addition of 

new layer I.

Removal of 

layer H to 

regeneration, 

addition of 

new layer J.

Removal o

layers C an

D to dispos

addition o

regenerate

layer H an

new layer K 

Walsum 9 Catalyst Exchange Logbook
Walsum Unit 9

High-Dust SCR

Comments and Costs:- Initial fill of 4 half plate layers was set to 

the initial cost. 

- Total catalyst exchange cost during the 

operating hours was found to be:

- For catalyst replacement 7 (4 initial 

new half layers (= 175% of initial cosadditional layers (= 25% of initial coregenerated replacement layer (= 25

- For field labor cost for the installatio

the removal of 5 half layers was fouinitial catalyst cost = 120%.

- Total catalyst replacement costs = 345% 

cost per 1,000 operating hours.
Weiher Power Station

- 710 MW PC wall-fired, drybottom boiler. - Saar regional bituminous 

coal, ash < 15%, sulfur < 1.5%.

- High-dust SCR system, 

honeycomb catalyst.

- Wet CaCO3 forced oxidation 

FGD system producing wall board quality gypsum, no reheat, flue gas discharge via cooling tower

- Operator: Steag- Owner: Steag- Power Purchaser: RWE

Weiher

Power Station
Weiher Unit 3

High-Dust SCR

Weiher Power Station Unit 3

- 10,000 20,000 30,000 40,000 50,000 

SCR operating hours

DeNOx potential P 

Weiher 3 

SCR Commissioning in 1990:- 3 layers of honeycomb catalyst (installe- 1 spare layer (layer 4).Coal switch from Weiher coal to Bexbach regional mines) caused formation of strolayers due to high CaO content in the fly 
Weiher Unit 3

High-Dust SCR

4.2 D (new) D D D (reg) D 

4.13.2 C A (reg) A A E (new) 

3.1

B 2.2 B C (reg) C C 

2.11.2 A B (reg) B 

1.1

layer

26,631 32,868 36,681 42,627 45,853 

Addition 

of new 

honeycomb 

layer D.

Removal of 

layers A, C to 

regeneration, 

addition of 

regenerated 

layer A.

Removal of 

layer B to 

regeneration, 

addition of 

regenerated 

layer C.

Addition of 

regenerated 

layer B, 

regeneration 

of layer D.

Remova

layer A 

regenera

addition 

new hon

comb lay

Weiher 3 Catalyst Exchange Logbook
Weiher Unit 3

High-Dust SCR

-2-

Comments and Costs:- Initial fill of 3 honeycomb layers was se

of the initial cost.

- Total catalyst exchange cost during the 

operating hours was found to be:

- For catalyst replacement 5 (3 initial 

new layers (= 167% of initial cost) preplacement layers (= 67% of initial 

- For field labor cost for the removal 

of 9 layers was found to be 17 x 10% cost = 170%.

- Total catalyst replacement costs = 404% 

cost per 1,000 operating hours.

- Note that after the switch to Bexbach co

deactivation rate increased significantly formations of strong surface blinding la
Leuna Refinery Cogeneration Plan

- Units 1 – 3 combined:

- 178 MW electricity (total).- 208 MW process steam (total).- All liquid/slurry wall-fired, dry bottom bo- Pet coke and refinery 

residues, ash < 5%, sulfur > 3.5%.

- High-dust SCR systems, 

plate catalyst.

- Wet lime forced oxidation 

FGD systems producing wall board quality gypsum, flue gas reheat via steam coil.

- Operator: Steag- Owner: Steag- Power Purchaser: Total 

Fina ELF Refinery

Leuna

Cogeneration Plant
Leuna

Cogeneration Plant

Leuna Units 1, 2 and 3

- 10,000 20,000 30,000 40,000 

SCR operating hours

DeNOx potential P 

P U1 P U2 P U3

SCR Commissioning in 1996/97:- 2 layers of plate catalyst (installed in lay- 1 spare layer (layer 3).Deactivation highly dependent on fuel cocomposition highly variable. Honeycomb deactivated very rapidly. Since then only 

Leuna 1, 2 and 3 
Leuna

Cogeneration Plant

G used 

out for regen. C F A A, B B 

F F H (new) H H H 

E E C (reg) C C C 

U3

D D D F (reg) F F C G (new) G G G A (reg) 

U2

B B B B D (reg) D A A E (reg) E E E B 

U1

hours 0 30,178 32,813 33,994 37,772 40,470 5

Leuna 1, 2 and 3 Catalyst Exchange Logbook

Removal of 

layer C to 

regeneration, 

purchase of 

a new honeycomb layer 

G.

Removal of 

layers A, E, F 

to 

regeneration, 

purchase of a 

new plate 

layer H, 

addition of 

regenerated 

layers E, C.

Removal of 

layer D to 

regeneration, 

addition of 

regenerated 

layer F.

Removal of 

layer G, 

addition of 

regenerated 

layer A.

Removal of la

regeneration

regenerated la

Rem

lay

addi

regen

lay
Leuna

Cogeneration Plant

Comments and Costs:- Initial fill of 6 plate layers (2 per unit) wa

100% of the initial cost.

- Total catalyst exchange cost during the 

operating hours for all 3 units was foun

- For catalyst replacement 8 (6 initial 

new layers (= 133% of initial cost) preplacement layers (= 83% of initial 

- For field labor cost for the removal 

of 13 layers was found to be 26 x 10cost = 260%.

- Total catalyst replacement for costs all 

2.27% of initial cost per 1,000 operating 

- Note that honeycomb catalyst was foun

more rapidly than plate catalyst. It was plate catalyst, regenerated and used els
Summary and 

Conclusions

Summary and Conclusions:

Specific catalyst cost vary highly depend- The SCR arrangement – tail-end approx

high-dust despite extensive use of rege

- The fuel – high ash (i.e. waste coal) ver

PRB) versus high vanadium (i.e. Pet co

Specific Catalyst Co

0123456

Herne 3 Herne 4 Voerde 4 Walsum 

% per 1,000 h 
Summary and 

Conclusions

Summary and Conclusions:- Catalyst is viewed and treated by Steag 

however not all catalyst types are suitaapplications. 

- Each type of catalyst has its distinct ad

disadvantages. The selection of the besrequires an economic evaluation on a c

- The use of new versus regenerated cata

on market conditions and prices. The pcatalyst varied between 25% and 65% odepending on the price of new catalyst regeneration process used and required

- Steag found no difference in longevity o

between regenerated and new catalyst. SO2/SO3 conversion rate may differ sign

on the regeneration process used.
Steag

Steag‘s SCR 

experience: 

~ 2 million hours 

of SCR operation

?Questions?