impact of modified boiler control settings on mercury...

ENERGY RESEARCH CENTER

Dr. Carlos E. RomeroMr. John W. Sale

Impact of Modified Boiler Control Settings on Mercury Emissions

Pennsylvania DEP MercuryWorkgroup Presentation

November 18, 2005

This contains proprietary and confidential information of the Energy Research Center. Unauthorized copying or dissemination is strictly prohibited.

IMPACT/IMPORTANCE OF BOILER OPERATING CONDITIONS ON MERCURY

Link between boiler conditions and Hg emissions:

Time-temperature history - flue gas temperature, APH performance, stack flow.Fly ash characteristics - mill classification, low-NOx firing system operation, fuel blending.Flue gas conditions – excess O2level, reduced NOx emission level.Other links - operating practices, boiler load profile, sootblowing, etc.

These variables ensure that Hg speciation is site-specific.

The fate of Hg emissions is impacted by the chemical and physical processes occurring in the boiler:

Homogeneous Hg oxidation.Heterogeneous oxidation and adsorption.

Importance of getting a handle on the operating conditions impacts:

Interpretation of Hg test data.Development of Hg emissions control options.Reduce the cost of compliance.

Analytical capabilities:Baldwin, Apogee and PSA filtration probes.Pretreatment/conditioning units.PSA SCEM’s for Hg speciation.OHM with EPA Method 17 (performed on-site).Coal, pyrite and fly ash sampling (ultimate, proximate, and Hg, Cl, S, LOI analyses).

Oxygen analysis

Frequent replacement of

syringe and septum

Independent check of MFC

Direct measurementof HgO source (CavKit outlet)

Oxygen analysis

Sample Gas Conditioning & Transport

Direct instrument

calibration

Independent check leakage

of probe Gold trap & Hg Lamp

High spanBlank

High spanBlank

High spanBlank

Sample GasExtraction

Hg Measurement

FIELD TESTING

Test Program:Boiler optimization - ten-days including baselining, parametric testing, and optimal condition tests. AC injection testing – ten-days including different AC rates under normal and optimal low-Hg operating conditions.

PARAMETERS USED IN BOILER OPTIMIZATION FOR MERCURY EMISSIONS REDUCTION

Excess airOverfire air registersMills

ClassificationOut-of-service configuration and coal biasing

Back-end temperature – steam coils and bypass dampersElectrostatic precipitator – field energization and rappingSootblowing

UNIT DESCRIPTIONSUnit A –

250 MW, CE boiler with a LNCFS-III low-NOx system.Fires bituminous coals, 0.06 ppm avg. Hg.Ljungstrom APH with on-line rot. speed adjustment.Two ESPs in series, 560 ft2/1000 acfm.

Unit B -650 MW B&W boiler with DRB-XCL low-NOx burners and rotating dynamic classifiers.Fires bituminous coals, 0.06 ppm avg. Hg.Ljungstrom APH with on-line rot. speed adjustment.Two ESPs in series, 660 ft2/1000 acfm.

Effect of Combustion Conditions on Total Hg New Cold ESP Inlet

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

0 50 100 150 200 250 300 350 400 450 500

Time (min.)

Tota

l Gas

eous

Hg

Con

cent

ratio

n (u

g/ds

cm @

3%

O2) 4-Mills I/S

OFAs at 80/10/5%Excess O2 = 2.5%

4-Mills I/SOFAs at 80/10/5%Excess O2 = 3.5%



3-Mills I/SOFAs at 5/5/5%

Excess O2 = 2.2%


LOI = 18.8%

LOI = 17.4%

LOI = 22.3%

LOI = 18.0%

LOI = 20.7%

LOI = 22.1%

FIELD FEASIBILITY TEST RESULTS –UNIT A

Sootblowing Effect (on 1/28-29/2004)

0.5

1.0

1.5

2.0

2.5

3.0

1/28/0419:12

1/28/0420:09

1/28/0421:07

1/28/0422:04

1/28/0423:02

1/29/040:00

1/29/040:57

1/29/041:55

1/29/042:52

1/29/043:50

1/29/044:48

1/29/045:45

1/29/046:43

1/29/047:40

1/29/048:38

1/29/049:36

Time

Exce

ss O

2 (%

) / H

g (u

g/ds

cm)

250

252

254

256

258

260

262

264

Flue

Gas

Tem

pera

ture

(deg

. F)

O2HgNew ESP inlet TemperatureStack Temperature

APH IR 15, IR 21 IK 3 APH IR 17, IR 25 IK 4 APH IR 2-9

FIELD FEASIBILITY TEST RESULTS –UNIT A

DETAILED HG OPTIMIZATION – UNIT ATotal Mercury Concentration at the Stack

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0Tes

t 1 - B

aseli

neTes

t 2 - L

ow N

OxTes

t 3 - L

ow N

Ox

Test 4

Test 5

Test 6

- Low

NOx

Test 7

Test 8

Test 9

Test 1

0Tes

t 11

Test 1

2Tes

t 13 -

Low H

gTes

t 14 -

Low H

g

HgT C

once

ntra

tion

at N

ew E

SPou

tlet (

ug/d

scm

)SCEMOHMNOx = 0.328 lb/MBtu

CO = 11 ppm

NOx = 0.263 lb/MBtuCO = 98 ppm

AC FIELD TEST RESULTS – UNIT AActivated Carbon - Mercury Tests

0.0

20.0

40.0

60.0

80.0

100.0

120.0

0.0 5.0 10.0 15.0 20.0 25.0 30.0

AC Normalized Injection Rate [lb/MMacf]

HgT

Rem

oval

Effi

cien

cy (%

)(B

ased

on

APH

inle

t-E

SPou

tlet)

BL+AC InjectionLow-Hg+AC Injection

Calculated Injection RateAssumes a 33,350 kschStack Flow @ 272 deg. F

DETAILED HG OPTIMIZATION – UNIT BTotal Mercury Concentration at the Stack

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

Test 1

- Bas

eline

Test 2

- Bas

eline

Test 3

- Bas

eline

Test 4

- Bas

eline

Test 5

Test 6

Test 7

Test 8

Test 9

Test 1

0Tes

t 11 -

Low H

gTes

t 12 -

Low H

gTes

t 13 -

Bas

eline

Test 1

4 - B

aseli

ne

HgT C

once

ntra

tion

at N

ew E

SPou

tlet (

ug/d

scm

)SCEM

OHM

Outlier

FIELD TEST RESULTS – UNIT BActivated Carbon - Mercury Tests

0

10

20

30

40

50

60

70

80

90

100

110

0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 16.0 18.0

AC Normalized Injection Rate [lb/MMacf]

HgT

Rem

oval

Effi

cien

cy (%

)(B

ased

on

APH

inle

t-E

SPou

tlet)

BL+AC Injection

Low Hg+AC Injection

Calculated Injection RateAssumes a 82,500 kschStack Flow @ 272 deg. F

AC FIELD TEST RESULTS – UNIT BActivated Carbon - Mercury Tests

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

BL1 BL2 BL3BL+

8 AC

BL+8 A

CBL+

16 A

CBL+

16 A

CBL+

6 AC

BL+6 A

CLo

w-Hg

Low H

g+9 A

C

Low-H

g+9 A

C

Low H

g+3 A

C

Low H

g+3 A

C

Low H

g+12

AC

Low H

g+12

AC

Low H

g+15

AC

BL+3 A

CBL+

3 AC

BL+3 A

C

Low H

g+10

AC

Low H

g+10

AC

Stac

k H

gT Con

cent

ratio

n (u

g/nm

3 @ 3

% O

2)

OHM

SCEM

Field Test Results Field Test Results –– Unit CUnit C

2,000

2,500

3,000

3,500

4,000

4,500

5,000

5,500

6,000

9:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00 17:00 18:00 19:00 20:00 21:00 22:00 23:00

Stac

k H

g C

once

ntra

tion

[ng/

m3 , c

orre

cted

@ 3

% O

2]

3.0

3.5

4.0

4.5

5.0

5.5

6.0

6.5

Ave

rage

Eco

nom

izer

Exc

ess

O2 [

%]

Hg

Avg. Excess O2

BL Conditions@ 115 MW

BL Conditions@ 95 MW

Low-NOx Settings@ 115 MW

Load to 85 MW

Field Test Results Field Test Results –– Unit CUnit C

1,000

2,000

3,000

4,000

5,000

6,000

7,000

8,000

9,000

10,000

6:00 7:00 8:00 9:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00 17:00 18:00 19:00 20:00 21:00 22:00 23:00 0:00 1:00 2:00

Stac

k H

g C

once

ntra

tion

(n

g/m

3 , cor

rect

ed @

3%

O2]

0

20

40

60

80

100

120

140

Load

[Mw

net]

HgLoad

Instrument Calibration

At Low-NOx Settings:Excess O2 ~ 3.5%

OFA Registers = 90%Burner Shrouds = -10%

Bi

Soot

blow

ing

IKs

10, 1

3, 1

4, 1

5, 1

7, 1

8, 1

9, 2

2

Soot

blow

ing

IKs

10, 1

3, 1

4, 1

5, 1

7, 1

8, 1

9,

Soot

blow

ing

AH

N &

AH

S

Soot

blow

ing

AH

N &

AH

S

Soot

blow

ing

IKs

10, 1

3, 1

4, 1

5, 1

7, 1

8, 1

9,

Soot

blow

ing

AH

N &

AH

S

Soot

blow

ing

IKs

10, 1

3, 1

4, 1

5, 1

7, 1

8, 1

9,

Soot

blow

ing

AH

N &

AH

S

CONCLUSIONS

Testing performed at four units burning bituminous coals and one unit burning sub-bituminous coals confirmed the merit of optimizing boiler operation through changes to the control settings for mercury emissions reduction.The mercury optimization also resulted in a NOxemissions reductions co-benefit.

Questions …

For More Information: John W. Sale

Manager, Program Development Lehigh UniversityEnergy Research Center

117 ATLSS DriveBethlehem, PA 18015-4729

Telephone: (610) 758-4545 Cell: (610) 442-5930 Fax: (610) 758-5959 Internet: [email protected]

www.lehigh.edu/energy

impact of modified boiler control settings on mercury...

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