Taiwan Power Research Institute The management of SCR de

The 30th CRIEPI/TPC General Meeting19th November 2018, Japan

Taiwan Power Research Institute

The management of SCR de-NOx catalyst activity and the study of developing new

catalyst for thermal power plants

1

Chih-Fu TsengChemistry and Environment Laboratory

Taiwan Power Research InstituteNovember 19, 2018


Taiwan Power Research Institute2

A. Background

B. The management of SCR catalyst

C. Developing low temperature SCR catalyst

D. Conclusion



Air pollution from thermal power plants

NOx

Coal-fired Power Plants

SOx

Nitrogen oxides(NOx) and sulfur oxides(SOx) are the source of acid rain.

NOx and SOx are the major precursor of fine particulate matter (PM2.5).

NOx is also the major source of ozone(O3) formation.

NOx may react with ozone(O3) and unsaturated hydrocarbons to form photochemical smog(i.e., PAN, PBN and PPN).

PMs


Taiwan Power Research InstituteSCR4

4NO + 4NH3 + O2 → 4N2 + 6H2O

Typical AQCS in coal-fired power plants

AQCS=Air Quality Control System

SCR system

Honeycomb Catalyst



4NO + 4NH3 + O2 → 4N2 + 6H2O (Major)6NO + 4NH3 → 5N2 + 6H2O2NO2 + 4NH3 + O2 → 3N2 + 6H2O6NO2+ 8NH3 → 7N2 + 12H2ONO + NO2 + 2NH3 → 2N2 + 3H2O

The mechanism of SCR(Selective Catalyst Reduction)

NOx usually refers to NO and NO2. NOx from combustion sources

contains about 90~95% of NO and 5~10% of NO2.



Power Plant Unit Capacity(MW) Fuel DeNOx PM DeSOx

Hsieh-ho #1~#4 500x4 Oil LNB+OFA ESP

Linkou new#1~new#2new#3(future) 800x3 Coal LNB+OFA+SCR Baghouse FGD

(seawater)

Tatan #1~#6 (725~743)x6 GasLNB(#1~#3)

LNB+SCR(#4~#6future)

Tunghsiao

new#1~new#2new#3(future) 893x3 Gas LNB+SCR

#4~#6 (313~386) x3 Gas LNB+waterinjection

Taichung #1~#10 550x10 Coal LNB+OFA+SCR ESP FGD(limestone)

Hsinta#1~#4 (500~550)x4 Coal LNB+OFA+SCR ESP FGD

(limestone)

#5~#9 445x5 Gas6

The AQCS of thermal power plants in Taipower

AQCS=Air Quality Control System



Power Plant Unit Capacity(MW) Fuel DeNOx PM DeSOx

Talin

new#1new#2(future) 800x2 Coal LNB+OFA+SCR Baghouse FGD

(seawater)

#3~#4 375x2 Oil LNB+OFA ESP

#5~#6 500x2 Gas LNB+OFA(#5)LNB(#6)

Nanpu #1~#4 (251~289)x3 Gas LNB

Chienshan #1~#12 10x12 Oil SCR Cyclone

Tashan #1~#8 8x8 Oil

7

The AQCS of thermal power plants in Taipower

Note: LNB=Low NOx Burner, OFA=Overfire Air, SCR=Selective Catalyst Reduction, ESP=Electrostatic Precipitator, FGD=Flue Gas Desulfurization



Power Plant Unit Unit Type Capacity(MW) Catalyst Type

Taichung #1~#10 Coal Fired Boiler 550x10 Plate、Corrugated

Hsinta #1~#4 Coal Fired Boiler (500~550)x4 Plate、Honeycomb

Linkou new#1~new#2new#3(future)

Coal Fired Boiler 800x3 Honeycomb

Talin new#1new#2(future)

Coal Fired Boiler 800x2 Honeycomb

Tatan #4~#6 Nature Gas Combine Cycle (725~743)x3 Honeycomb

Tunghsiao new#1~new#2new#3(future)

Nature Gas Combine Cycle 893x3 Honeycomb

Chienshan #1~#12 Oil Fired Boiler 10x12 Honeycomb

Total ~16,600

The Capacity of SCR catalyst



Performance Honeycomb Plate Corrugated

Activity ◎ △ ○

Geometric Surface Area ◎ △ ○

Pressure Loss △ ◎ ○

Erosion ○ ◎ △Weight ○ △ ◎

Plugging ○ ◎ ○

Na,K,As,Ca Poison ○ ○ ◎9

Comparison of SCR catalyst typeHoneycomb Catalyst

CeramicLarge surface areaWeak strengthLong lifetimeUsed in High/Low dust

Plate CatalystActive mater coated on metal supportLarge gapLow pressure lossHigh strengthUsed in High/Low dust

Corrugated CatalystContained glass fiberMedium surface areaHigh thermal stabilityLightweight



Catalyst Deactivation Mechanisms

Chemical Poison(ex: K, Na, As, P)MaskingChannel/Pore PluggingErosionThermal Sintering

Chemical Poison

Masking

Channel Plugging

Erosion

Thermal Sintering



Life cycle of SCR catalyst at thermal power plants

Purchase

•Specification•Contract

Monitor

•Operating Control•Root Cause Solving•Lifetime Assessment•Catalyst Database

Dispose

•Landfill Disposal

Recycle

• Recycling of Metals• Used in Concrete

Renew

• Washing• Rejuvenation• Regeneration



Assessment of SCR catalyst performance

DeNOx Micro Reactor

DeNOxEfficiency SEM ICP-OES

Specific Surface

AreaPore

VolumePressure

Loss

Acidity of Metal SO2 to SO3

ErosionResistance

CrushStrength

Hg Oxidation TGA

Laboratory Equipment

Root Cause Analysis(deactivation, poison) Lifetime Assessment Catalyst Database

Catalyst Online Sampling



Measurement of SCR catalyst deactivation rate

DeNOx Efficiency𝜂𝜂 =

𝐼𝐼𝐼𝐼𝐼𝐼𝐼𝐼𝐼𝐼 𝑁𝑁𝑁𝑁𝑁𝑁 − 𝑁𝑁𝑂𝑂𝐼𝐼𝐼𝐼𝐼𝐼𝐼𝐼 𝑁𝑁𝑁𝑁𝑁𝑁𝐼𝐼𝐼𝐼𝐼𝐼𝐼𝐼𝐼𝐼 𝑁𝑁𝑁𝑁𝑁𝑁

, %

Area VelocityAV= 𝐹𝐹𝐹𝐹𝐹𝐹𝐹𝐹 𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟(𝑁𝑁𝑁𝑁3/ℎ𝑟𝑟)

𝑆𝑆𝑆𝑆𝑟𝑟𝑆𝑆𝑟𝑟𝑆𝑆𝑟𝑟 𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟(𝑁𝑁2), m/hr

Catalyst activityK= −𝐴𝐴𝐴𝐴 ln(1- 𝜂𝜂) , m/hr

K/K0 Relative activity measured in %,

dictates deactivation rate Typical catalyst replacement time

comes at 0.60~0.65

After operating 18000 hours, these SCR catalysts deactivation rate are about 0.86~0.91(K/Ko)

0.75

0.8

0.85

0.9

0.95

1

0 5000 10000 15000 20000

K/K 0

operation time(hr)

U1-A-1U1-A-2U1-B-1U1-B-2



Chemical composition of several SCR honeycomb catalysts

Compound (wt%) C brand C brand S brand J brand A brandCell number 70 22 21 22 21

TiO2 84.18 91.77 77.60 87.58 77.49V2O5 2.56 0.23 0.88 0.56 0.87WO3 5.94 1.17 8.02 4.57 7.89Al2O3 0.90 0.92 1.62 0.65 1.64K2O 0.10 0.03 0.44 0.41 0.46

MgO 0.05 0.28 0.03 0.00 0.03Na2O 0.04 0.03 0.11 0.09 0.11SiO2 3.93 3.37 8.79 4.19 8.87CaO 1.24 1.09 1.71 0.82 1.72SO3 1.04 1.08 0.79 1.13 0.91



Specific Surface Area and Pore Distribution

0.5

0.6

0.7

0.8

0.9

1

0 5000 10000 15000 20000

Ratio

(BET

/BET

0)

Operation Time(hr)

U1-A-1U1-A-2U1-B-1U1-B-2

0

0.0002

0.0004

0.0006

0.0008

0.001

0.0012

10 100 1000dV/d

DPo

re V

olum

e (c

m³/g

·Å)

Pore Diameter (Å)

Fresh, ReferenceU1-B-1, 9360 hrsU1-B-1, 12600 hrsU1-B-1, 15480 hrsU1-B-1, 18000 hrs

<20Å microporous20~500Å mesoporous>500Å macroporous

Decreasing specific surface area was caused by plugged,masked or thermal sintering.

The pore on the catalysts was plugged by fine particles or harmful matters.



Microscopic Structure

Fresh catalyst have a smooth surface, but exposed catalyst have a rough surface with foreign matters and glass fiber due to erosion.

On the exposed catalyst surface, we can find fly ash and CaSO4 deposit and glass fiber bare obviously.

Fresh catalyst

Exposed catalyst

Fly ash and CaSO4

Glass fiber



SCR Catalyst Replacement Time1st Layer K1/AV1

2nd Layer K2/AV2

3rd Layer K3/AV3

Reactor Potential (P=K/AV)to evaluate the total SCR catalysts performancePreactor=Player1 + Player2 + Player3+…

=K1/AV1+ K2/AV2 + K3/AV3 +…

SCR



Advantage of low temperature SCR catalyst

SCR Catalyst Synthesis

Honeycomb Catalyst Preparation

Pilot Test

Commercial Assessment

Setting SCR after ESP/BH can avoid it from plugging/mask/erosion by fly ash.

Setting SCR after FGD can avoid SO2poison and NH4HSO4 formation.

Catalyst’s lifetime can be extended and maintenance cost can be reduced.

SCR Pilot Test

Catalyst



Low temperature SCR catalyst and traditional SCR catalyst

MnFe/TiO2 (this study):

100 ℃ ~300℃V2O5-WO3/TiO2(tradition):

300 ℃ ~400℃Different active metal has

different operating temperature

0

10

20

30

40

50

60

70

80

90

100

0 100 200 300 400

NO

con

vers

ion,

%

Temperature, ℃

V2O5-WO3/TiO2

MnFe/TiO2(This study)



9996

80

71

98 95

8377

50

60

70

80

90

100

110

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

NO

Con

vers

ion

(%)

H2O (v/v %)

MnFeCe MnFe

20

DeNOx in laboratory test

0

10

20

30

40

50

60

70

52

25

48

MnFeCe/AK-1MnFeCu/AK-1MnFe/AK-1

NO C

onve

rsion

(%)

Condition：[NO]=200ppm, [NH3]=200ppm, [H2O]=10 v/v %, Space Velocity=25,000 hr-1, temperature= 105 oC

253035404550556065707580859095

100

100 110 120 130 140 150 160 170 180 190 200

NO

Con

vers

ion

(%)

Temperature (℃)

MnFeCeMnFe

Condition：[NO]=200ppm, [NH3]=200ppm, [H2O]=0~15 v/v %, Space Velocity=25,000 hr-1, temperature= 140 oC

Condition：[NO]=200ppm, [NH3]=200ppm, [H2O]=10 v/v %, Space Velocity=25,000 hr-1, temperature= 100~200 oC

Change of Temp.

Change of Active Metal

Change of H2O



Flow Chart of Pilot Test

1.Optimization of catalyst recipe:Mn(20)Fe(10)/TiO2Co-precipitation method

2.Honeycomb catalyst cube:150mm*150mm*100mm (100 cpsi)Catalyst is coated on Cordierite support

3.Catalyst module:4*4=16 piece/layervolme:0.036m3/layer

4.Pilot test:DeNOx test behind HRSG exhaust in Tatan(大潭) power plant

Catalyst Powder Honeycomb Catalyst Cube

Catalyst ModulePilot Test



Pilot test configuration and flue gas conditionFlue gas

compositionFlue gas flow rate Temp. NOx

(dry@15% O2)H2O (wet)

O2(dry)

CO2(dry)

SO2(dry@15% O2)

SO3(dry@15% O2)

N2(dry)

Unit Nm3/min ℃ ppm % % % ppm ppm %Value 10 90~100 13~16 11.15 13.58 4.5 0.01 0.01 balance

Inlet gasfrom HRSG Outlet gas

Reactor

NH3 cylinder

ID fan Heater

NH3 injection

Pilot test at #3-1 unit in Tatan (大潭) power plant (NGCC)



The Result of Pilot testSpace Velocity = 𝐹𝐹𝐹𝐹𝐹𝐹𝐹𝐹 𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟(𝑁𝑁𝑁𝑁3/ℎ𝑟𝑟)

𝑆𝑆𝑟𝑟𝑟𝑟𝑟𝑟𝐹𝐹𝑐𝑐𝑐𝑐𝑟𝑟 𝑣𝑣𝐹𝐹𝐹𝐹𝑆𝑆𝑁𝑁𝑟𝑟(𝑁𝑁3)

Condition：[NOx]inlet=13ppm, [NH3]/[NO]=1.0, [H2O]=11%, [O2]=13.5%, [CO2]=4.5%, Space Velocity =4,200 hr-1

Condition：[NOx]inlet=13ppm, [NH3]/[NO]=1.0, [H2O]=11%, [O2]=13.5%, [CO2]=4.5%, Temperature=150 oC or 160 oC

Change of Temperature Change of Space Velocity



The SCR capacity in Taipower companyis about 16,600MW and it will still increase in the future due to more stricter environmental regulations.

The management of SCR catalyst to monitor the activity by several methods. Thus, we can clearly evaluate the catalyst lifetime.

Low temperature SCR catalysthas been synthesis successfully, such as MnFe/TiO2 has high de-NOx efficiency. We have already implement SCR pilot test, and still in progress.



Documents

Taiwan Power Research Institute The management of SCR de