The document discusses the evaluation of dry sorbent injection (DSI) technologies for controlling emissions of sulfur dioxide, acid gases, and mercury in utilities. It emphasizes the need for accurate real-time data on removal efficiency, considering various factors such as sorbent type, injection rate, and testing methods. The paper highlights the importance of advanced stack testing techniques, like FTIR, to provide reliable data for optimal DSI performance.

1. Use of Advanced StackTesting
Technologies to Perform DSI
Evaluation Studies
Thomas A. Dunder, Ph.D.
Principal Scientist - FTIR Emissions Testing
TRC Environmental Corporation
EUEC Paper C5 -1, February 4, 2014
Phoenix, Arizona
1

2. The Challenge – Accurate, Real-
Time, Multi-Location Data
2
 Dry sorbent injection (DSI) is an option for utilities to
control SO2, acid gases (HCl, HF) and mercury (Hg)
emissions. There are numerous sorbent options
specifically for SO2/acid gases or Hg control
 DSI must be evaluated at each facility to determine
optimal sorbents, injection rate, and injection points.
 DSI studies require accurate and sensitive real-time
emissions/removal efficiency data to identify the
ideal sorbent parameters. There are testing options
that vary in cost and data quality.
 Costly decisions are made based on a DSI
evaluation so quality data is critical.

3. Consideration for DSI Evaluation –
Testing Prospective
 Sorbent (Lime, SBC, Trona (Acid Gas/SO2),
PAC (Hg), newly developed sorbents)
◦ Vary in cost, effectiveness
 Injection Rate to meet MATS limits
 Injection Location
◦ Maximize gas-particle interaction
 Sorbent Particle Size – on-site mill?
 Sorbent Interaction
◦ Sorbent-Sorbent (PAC/Acid Gas Sorbents)
◦ NH3/SO3 added to gas stream
3

4. DSI Evaluation Data Requirements
 Removal efficiency for HCl, HF, SO2 and Hg
as a function of sorbent and injection rate
 Extended test periods to ensure stable
plant and sorbent equilibration conditions
 On-site data to evaluate DSI effectiveness
and modify injection rates as needed
 Mapping of removal efficiency over a
range of injection conditions to ensure MATS
compliance now and in the future
 Detailed test plan with close coordination
between plant, DSI vendor, and test team
4

5. What needs to be measured?
 Acid Gases (HCl, HF) – removal efficiency
 Mercury (elemental, oxidized, particle bound)
– removal efficiency
 Sulfur Dioxide - removal efficiency
 Particulate Matter – demonstrate no
emissions impact due to sorbent
 O2/CO2 – emission rate determination
 Fuel Analysis – F Factor for lb/MMBtu
emission rate (cannot use ppmin vs ppmout)
5

6. What are the Testing Options?
 Multiple test methods available for acid
gases, mercury, SO2
◦ “manual” methods- impinger, sorbent tube
◦ real-time instrumental technologies
 Data collection points
◦ Measure at stack only (DSI off=baseline)
◦ Measure upstream/downstream of DSI
injection for true removal efficiency
◦ Stack-only data assumes no variation in
plant emissions/DSI rates to determine
removal efficiencies. 6

7. DSI Source Testing Demonstration Options
Option Benefit Risks/Challenges
Testing at Stack Only
with Manual Sampling
(M26A, M30B) and M6C
(SO2)
Lower Cost Composite samples - no real-time,
on-site data. Sensitivity issues.
No data on source/DSI variation
No true removal efficiency data
Testing at Stack Only
using Instrumental
Methods (M320, M30A)
Real-time, on-site data Increased cost. Specialized
equipment and personnel needed.
No data on source/DSI variation
No true removal efficiency data
Upstream/Downstream
Testing using
Instrumental Methods
Real-time, on-site data
including removal
efficiency. Detect
plant/DSI variations.
Select optimal, stable
time periods
Increased cost. Specialized
equipment and personnel needed.
7

8. Testing Diagram
8
Fabric Filter
or ESP
Coal-Fired Boiler
Sorbent Injection
(Economizer
Outlet, Air Heater
Inlet or Outlet)
Inlet Sample
Stack
Sample
Hg, FTIR
Analyzers

9. Testing Options – Acid Gases
 EPA Method 320
◦ FTIR (Fourier Transform Infrared)
◦ Instrumental Test Method with real-time
data (typically 1 minute response)
◦ Multicomponent detection (coal-fired
utility: HCl, HF, CO, CO2, H2O, NO, NO2,
N2O, SO2, HBr…)
◦ High sensitivity (~50 ppb HCl detection
limit)
◦ All spectral data archived for reanalysis
9

10. TRC FTIR Lab – Paired FTIRs,
Heated Sampling System
10

11. Mercury Testing Options
 Mercury can be measured by sorbent tube
(M30B) or real-time analyzer (M30A)
 Instrumental analysis gives speciated
(elemental/oxidized Hg) and continuous, 24
hour/day data
 Sorbent tubes can be analyzed on site for
same day data
 Equipment costs higher for instrumental
analysis, manpower costs higher for
sorbent tube
11

12. Real-Time Inlet/Outlet Testing
 Simultaneous data allows determination of:
◦ Plant stability
 Conditions like load change, plant upset, and
soot blow are not appropriate to determine DSI
efficiency
◦ DSI Stability
 Variable injection rate or injection interruption
conditions not appropriate
 Allow DSI to equilibrate – can take hours
 Equilibration critical for Fabric Filters
◦ Select data from stable plant/DSI time
periods to calculate efficiency 12

13. DSI Stability – Impact on Data
Quality
13
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0
50
100
150
200
250
300
7:05 8:11 9:18 10:24 11:30 12:36 13:42 14:49 15:55 17:01
HClppmvw
SO2ppmvw
Axis Title
SO2, HCl Inlet/Outlet Data During Sorbent Injection
SO2 Outlet SO2 Inlet HCl Outlet HCl Inlet
SO2 Inlet
SO2 Outlet
HCl Inlet
HCl Outlet
DSI Rate 1 DSI Rate 2
DSI Rate 3DSI Injection Failure

14. Plant Instability – Impact on Data
Quality
0
20000
40000
60000
80000
100000
120000
140000
0
50
100
150
200
250
300
350
400
7:12:00 AM 9:36:00 AM 12:00:00 PM 2:24:00 PM
H2O,CO2ppmvw
SO2,NOppmvw
Time
Stack Measurements - Plant Instability
SO2 NO
CO2 H2O
Steam Drum Leak Causes
Oscillating Emisions
Sorbent Off
14
Instability detected by FTIR – Control Room unaware

15. Sorbent Stabilization: Consecutive
4-Hour Test Periods
0
80
160
240
320
400
0%
20%
40%
60%
80%
100%
1 2 3 4 5 6
SO2ppmvw
%RemovalHCl,SO2
4-Hour Time Period
Consecutive 4-Hour SBC Injection Periods (2500 lb/hr)
HCl % Removal SO2 % Removal SO2 ppm In SO2 ppm Out
% HCl Removal
% SO2 Removal
SO2 Inlet ppmvw
SO2 Outlet ppmvw
15

16. Sorbent Stabilization: Consecutive
4-Hour Test Periods
0.0
0.2
0.4
0.6
0.8
1.0
0%
20%
40%
60%
80%
100%
1 2 3 4 5 6
SO2ppmvw
%RemovalHCl,SO2
4-Hour Time Period
Consecutive 4-Hour SBC Injection Periods (2500 lb/hr)
HCl % Removal SO2 % Removal HCl ppm In HCl ppm Out
% HCl Removal
% SO2 Removal
HCl Inlet ppmvw
HCl Outlet ppmvw
HCl and SO2 removal not
correlated
16

17. HCl % Removal vs. Injection Rate
-40%
-20%
0%
20%
40%
60%
80%
100%
0.0E+00
5.0E-04
1.0E-03
1.5E-03
2.0E-03
2.5E-03
0 1000 2000 3000 4000
%HClRemoval
lb/MMBtuHClEmissionRate
lb/hr Sorbent Injection Rate
HCl Emissions Versus Sorbent Injection Rate (SBC)
HCl lb/MMBtu
HCl MATS Limit
HCl % Removal
Below MATS Limit
without DSI
Limited reduction above
1600 lb/hr
17

18. SO2 % Removal vs. Injection Rate
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0 1000 2000 3000 4000
%SO2Removal
SO2lb/MMBtu
lb/hr Sorbent Injection Rate
SO2 Emissions Versus Sorbent Injection Rate
SO2 lb/MMBtu
SO2 MATS Limit
SO2 % Removal
18

19. QA Considerations for DSI
Evaluations (FTIRTesting)
 Primary focus of testing is long term,
extended measurements with minimal
downtime for QA procedures
 Generally follow EPA Method requirements
with addition of:
◦ Measure one source with both FTIRs
simultaneously to verify inter-agreement
◦ Compare Plant CEMS data with FTIR (CO2, CO,
NOx, SO2)
◦ Compare FTIR data with other methods (M5
moisture)
19

20. DSI Study QA – Comparison with
Plant CEMS
0
50
100
150
200
250
5/28/2013 14:24 6/2/2013 14:24 6/7/2013 14:24 6/12/2013 14:24 6/17/2013 14:24
ppmvwSO2
Time
Comparison of Plant CEMS, FTIR SO2 Data
M320 SO2 CEM SO2
Average % Difference = 1.7%
20

21. Practical Testing Considerations
 Extended test- continuous 24/7
◦ Instrument/Sampling System Reliability
 Sampling System Issues
◦ Long sample lines @ 350 oF
◦ Inlet sampling – high particulate
 Monitor pump vacuum, utilize blowback
 Potential inlet scrubbing due to PM in probe filter
 Data reduced daily to select stable time
periods and reduce data (wet-dry, lb/MMBtu
calculation, % removal determination) to
provide feedback to EGU and DSI vendor 21

22. Test Data Feeds Into DSI Selection
 Test firm provides daily on-site data
summaries and final data (removal
efficiency, emission rate) to EGU and DSI
vendor
 EGU and DSI vendor process data to
compare sorbents and determine optimal
injection conditions
 Convert data to NSR (normalized
stoichiometric ratio) basis to allow sorbents
to be compared
22

23. Final Data: NSR Curve of SO2
Removal with SBC vs Trona
23

24. Conclusions
 Advanced instrumental stack testing
technologies like FTIR and Mercury CEMS
provide the time resolved, speciated data
needed for DSI evaluation
 Challenge for emissions testing firms to
provide advanced technology
instrumentation and perform the data-
intensive analysis, including on-site results
24

25. 25
Thanks for your attention
Any questions?
Thomas A. Dunder, Ph.D.
919.256.6242
tdunder@trcsolutions.com
www.trcsolutioons.com