Oslo, February 17th, 2010 - SINTEF

HIGH DUST SELECTIVE CATALYTIC NOx REDUCTION AT WTE P LANT IN BRESCIA

Paolo Rossignoli – Mario Nenci – Lorenzo Zaniboni A2A, Brescia, Italy

Oslo, February 17th, 2010

TERMOUTILIZZATORE(The waste to energy plant of Brescia)

••Waste preventionWaste prevention

••Separate collection (for material recycling)Separate collection (for material recycling)

••Composting of organic wasteComposting of organic waste

••Energy from remaining waste (renewable energy)Energy from remaining waste (renewable energy)

••LandfillingLandfilling minimization (only safe residues)minimization (only safe residues)

INTEGRATED WASTE MANAGEMENT SYSTEM

1. ENVIRONMENTAL PROTECTION

2. HIGH EFFICIENCY OF ENERGY RECOVERY

3. SAFETY, RELIABILITY, AVAILABILITY

DESIGN GOALS:



584 584 km of double pipekm of double pipe

130.000 inhabitants supplied130.000 inhabitants supplied

38,538,5 MmMm33 heated volumeheated volume

17.391 17.391 connected buildingsconnected buildings

695 695 MWMWthth

230 230 MWMWelel

1 km

P.Plant north

P.Plant south

WTE

DISTRICT HEATING SYSTEM OF BRESCIA


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Mm3

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2.00

2 2.

003

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4 2.

005

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6

YEARS

CONNECTED BUILDINGS VOLUMES




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GW

h

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ANNI

USED FUELS

• NAT. GAS

• OIL

• COAL

• SOLID WASTE and BIOMASSES



WASTE BUNKER


Combustion grate under construction

MAIN TECHNICAL DATA

• Heat capacity of treated waste (3 boilers) 310 MW

• Waste throughput 3 x 33 t/h

• Electrical generation capacity (net) 80 MWel

• Heat generation capacity 170 MWth

ISO 14001 Environmental certification in april 2006


OPERATIONAL DATA 2008

• Treated waste 801,000 tons( of which biomass 270.000 tons )

• Electricity production (net) 570 GWhel

• District heating 568 GWhth

• Fossil fuels saving (Tons of Oil Equivalent) > 150,000 TOE

• CO2 avoided emissions > 400,000 tons


NOx CONTROL METHODS

• PRIMARY (NOx prevention)

- staged combustion (gradual O 2 supply)

- combustion temperature control

• SECONDARY (NOx reduction)

- SNCR (Selective Non-Catalytic Reduction)

- SCR (Selective Catalytic Reduction):- “High dust” (on raw gas)- “Tail-end” (after gas cleaning)- “Low dust” (after gas de-dusting)

HIGH DUST SCR LOCATION


HIGH DUST SCR LAYOUT


MIXER

CATALYST LAYER

(SPACE FOR UP TO 5LAYERS)

FLUEGAS

DAMPERS

NOx NOx

IMPLEMENTED NOx CONTROL IN BRESCIA WTE(starting situation - since 1998)

• PRIMARY

- low combustion excess air

- 30 compartment grate

- infrared camera for optimization of primary andsecondary air supply

- flue gas recirculation

• SECONDARY (NOx reduction)

- SNCR (NH3 injection with 27 nozzles, positioned atthree levels)


SNCR DENOX SYSTEM



INSTALLATION AND TESTING OF A SCR “HIGH DUST” SYSTEM(non industrially available yet)

GOALS:

- further NOx reduction (120 �� 80 mg/Nm 3)

- ammonia slip improvement

- lowering ammonia consumption

- keep high energy plant efficiency

PROBLEMS:

- catalyst clogging- catalyst poisoning

ADVANTAGES:

- much higher energy efficiency (no need of gasreheating and lower gas pressure losses)

- simpler installation- lower investment and operating cost

SCR “HIGH DUST” SYSTEM(non industrially available yet)

• installation: 2005 Sep. – 2006 Feb.

• operation: started 2006 Mar. (1 st phase – one cat. layer)

• inspection: Sep. 2006 (cleaning and catalyst analysi sshowing some pore plugging and catalystpoisoning with sulphates)

• 2nd phase: started 2006 Oct. after inspection (2 cat. la yer)

• inspections: 2007 Apr. and Sep. (only cleaning)2008 Apr. (erosion starts to become evident)

November: removal of one layer and installation of a new 2008 layer

SCR “HIGH DUST”History highlights


SPACE FOR SCR HIGH DUST INSTALLATION


TERMOUTILIZZATORE(The waste to energy plant of Brescia

HIGH DUST SCR

SPACE FOR

SCR HIGH DUST

INSTALLATION

CATALYST UNDER CONSTRUCTION


NOx- NH3 emissions

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1/1/06 1/5/06 29/8/06 27/12/06 26/4/07 24/8/07 22/12/07 20/4/08 18/8/08 16/12/08 15/4/09 13/8/09 11/12/09

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x -

NH 3

stac

k em

issi

ons

[mg/

Nm

³]

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NH 3

cons

umpt

ion

[l/h]

NOx

NH3slip

NH3cons.

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1,3 1,83,7

SCR operation start (1 layer)

Start with

2nd layer

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2,5

70

44

33

53

66

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179

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184186

219200

44,9

NOx – NH3 consumption – ammonia slip

HIGH DUST SCR RESULTS


HIGH DUST SCR RESULTST , ∆∆∆∆p SCR

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3/7/06 31/10/06 28/2/07 28/6/07 26/10/07 23/2/08 22/6/08 20/10/08 17/2/09 17/6/09 15/10/09

T [°

C]

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[mba

r]

T SCR [°C]

Dp [mbar]

Start with

2nd layer

T gas – ∆p SCR


NOx and NH3 emissions monthly media 2006 - 2007 - 2 008 - 2009

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month

mg/

Nm

3

L1 NOx

L1 NH3

L2 NOX

L2 NH3


L1: SNCR only �� L2: SNCR + HD SCR (2 layers)

• NOx: 80 - 90 �� 60 - 70 mg/Nm 3

• NH3 slip: 10 - 30 �� 2 - 6 mg/Nm 3

• NH3 consumption: 0.22 �� 0.18 m3/h (25% concentrated )

• Pressure losses: negligible

SCR “HIGH DUST”

TEST RESULTS


• new geometry in order to increase plates stiffness

• increasing plates thickness

• new composition of the catalyst material in order t o

increase plates hardness

“HIGH DUST” SCR

Modifications of the catalyst to reduce erosion


CATALYST AFTER 2 YEARS OF OPERATION


Before Cleaning

After Cleaning

INSPECTION OCTOBER 2009CATALYST REMOVED AFTER 32 MONTHS OF OPERATION


HIGH DUST SCR


HIGH DUST SCR

INSPECTION OCTOBER

2009


HIGH DUST SCR

CATALYST REMOVED AFTER 32 MONTHS OF OPERATION


HIGH DUST SCR

CATALYST REMOVED AFTER 32 MONTHS OF OPERATION

HIGH DUST SCR

FUTURE TEST STEPS :

� monitoring of fouling and activity of catalyst with new g eometry

� optimization of catalyst layout (single / multiple la yers)

� optimization of duct cleaning with modified geometry

� lifetime assessment of the catalyst with new materials

� industrial cost evaluation


HIGH DUST SCR

CONCLUSIONS:

� improving the reaction between ammonia and NOx


� low impact on the plant efficiency: small pressure l osses and low impact on fan consumption

� life-time rather short, but costs relatively small in comparison with other SCR systems:

• costs for reheating the flue gas and energy for IDf an (vs Tail-end)

• costs for ammonia consumption (vs pure SNCR)

Oslo, February 17th, 2010 - SINTEF

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