Simultaneously Reducing NOx and Slagging on a T-Fired Boiler Long Term Test Results

April, 2012Copyright Siemens AG 2012. All rights reservedPROPRIETARY CONFIDENTIAL

BUSINESS INFORMATION

Simultaneously Reducing NOx and Slaggingon a T-Fired Boiler Long Term Test Results

Siemens Energy Inc.Advanced Burner Technologies Product Line

3040 US Highway 22 WestBranchburg, NJ 08876



Introduction

This presentation will describe the design, guarantee testing and long term testing of a tangentially fired low NOx combustion system.

The combustion system was installed at the Owensboro MunicipalUtilities (OMU) plant, Elmer Smith Unit #2.



Boiler and Required Guarantee Background

Fuel: Severely slagging midwesternbituminous coal

Operational Concerns:

Severe furnace slagging due to (1) High furnace heat release rate, (2) Low coal ash fusion temperatures

Furnace waterwall corrosion due to (1) Local reducing conditions and (2) High fuel sulfur content

Existing Boiler Information: 290 MW Single furnace Four burner levelsCCOFA

Guarantee Requirements: NOx guarantee: 308 mg/Nm3 CO:



Coal Analysis and Slagging Index

Sulfur, wt% 4.4Ash, wt% 21.3SiO2 40.6Al2O3 17.2Fe2O3 21.3CaO 6.7MgO 0.9K2O 1.9

Slagging Index Severe



Siemens Scope of Work

CFD modeling Fuel injector and combustion air OFA system Anti-corrosion and slagging system

Low NOx combustion equipment 16 new ABT Opti-Flow fuel injectors New combustion air buckets New one level SOFA system Anti-corrosion and slagging system



Burner Arrangement



Opti-FlowTM Low NOx BurnerT-Fired System Cut-Away



Low NOx Burner Nozzle

Heart of all Opti-Flow Low NOx burners

Produces 35% Lower NOx than early generation LNBs replaced by ABT and 60 to 70% below turbulent burners.

Open Nozzle, No Coking, Low Wear Geometry

AXIAL VANE

STABILIZER VANE



Derivation of Wall-Fired Technology to Tangentially-Fired Units

Fuel Injector for Wall-Fired Boiler

Fuel Injector for T-Fired Boiler



Opti-FlowTM Fuel Injector For OMU



Nozzle from Furnace Side

Cast Nozzle

Removable ErosionProtection Plug

Air Seal Assembly

NO Evidence ofErosion, Cracking

OrOverheating

After Two Years



Typical Nozzle After Two Years

No Evidence of Wear



Replaceable Central Deflector After 2 Years



T Fired Burner after Five Years Continuous Operation



Opti-Flow OFA System

Minimize sub-stoichiometric burner operation

Utilize single level of ports with two on each wall

Optimize the following: De-NOx zone residence time Residence time in the burnout zone



C

L

S

E

C

A

I

R

D

U

C

T

C

L

S

E

C

A

I

R

D

U

C

T

TAKEOFF FROM EXISTING SECONDARY AIR DUCT

NON-METALLIC EXPN JOINT-TYP

4' X 6' TYP

Opti-Flow OFA System



Opti-Flow Aerodynamic OFA Port

Single Stage Design

One Damper Controls Total Flow

Baffles Control Flow Pattern

No Swirl

Deep Penetration

Excellent Horizontal Mixing

High Reliability Only 1 Moving Part



Opti-Flow OFA Aerodynamic Penetration



Opti-Flow OFAs Effect On CO For ATangentially Fired Boiler



CFD Deposition Model Results

0.002 kg/m2-s

0

0.002 kg/m2-s

0

Previous Baseline ABT Final Case Previous BaselineABT Final Case

Baseline BaselineSiemens Case Siemens Case



Case Study:Owensboro Municipal Utilities

300 MW T-Fired BoilerSingle Furnace

4%+ Sulfur - High Slagging CoalSiemens Scope: New Burners; Sofa System And Anti-Corrosion System

Original System Performance Long Term Test

NOx:



NOx vs Load Results

0.2

0.3

0.4

0.5

150 200 250 300Load [MW ]

N

O

x

[

l

b

/

M

M

B

t

u

]

2.0

3.0

4.0

5.0

6.0

G

r

i

d

O

2

[

%

]

Grid O2

Baseline NOx

Post-Retrofit NOx

NOx Guarantee



LOI Performance

0.6

0.98

0.67

1.32

0.97

0.86

0

0.2

0.4

0.6

0.8

1

1.2

1.4

150 225 285Load [MW]

L

O

I

[

%

]

BaselinePost-Retrofit



Slagging Improvements

Pre-Retrofit:Severe slagging of furnace wallsBurners unable to tilt due to slag build-upDropping load required every shift to shed slag

Post-Retrofit:Furnace walls nearly completely cleanBurners are capable of tiltingNo dropping of load required after months of operation



Summary

A Siemens designed novel low NOx combustion system for tangentially fired units was implemented at OMUs Elmer Smith Plant, Unit #2.

Some technical challenges faced were: (1) high heat release furnace, (2) high sulfur, severe slagging coal.

Post Retrofit Results: NOx level of 287 mg/Nm3 CO emissions less than 100 ppm over the load range. Fly ash LOI less than 1% Severe furnace slagging practically eliminated



THANK YOU

Simultaneously Reducing NOx and Slagging on a T-Fired Boiler Long Term Test Results

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