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%
4-Mills I/SOFAs at 80/10/5%Excess O2 = 1.8%
3-Mills I/SOFAs at 100/90/5%Excess O2 = 2.2%
3-Mills I/SOFAs at 5/5/5%
Excess O2 = 2.2%
3-Mills I/SOFAs at 100/90/5%Excess O2 = 2.5%
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