stack testing technologies for dsi evaluation studies
DESCRIPTION
In this recent conference presentation, TRC's Tom Dunder compared various emissions testing strategies to provide the most accurate and useful data to coal-fired facilities undertaking dry sorbent injection studies.TRANSCRIPT
Use of Advanced Stack Testing
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
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.
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
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 team4
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
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
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 variationNo 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 variationNo 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
Testing Diagram
8
Fabric Filter
or ESP
Coal-Fired BoilerSorbent Injection
(Economizer
Outlet, Air Heater
Inlet or Outlet)
Inlet Sample
Stack
Sample
Hg, FTIR
Analyzers
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 reanalysis9
TRC FTIR Lab – Paired FTIRs,
Heated Sampling System
10
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 tube11
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
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
HCl
ppm
vw
SO2
ppm
vw
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 2DSI Rate 3DSI Injection Failure
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
H2
O, C
O2
pp
mvw
SO2
, NO
pp
mvw
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
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
SO2
pp
mvw
% R
em
ova
l HC
l, S
O2
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
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
SO2
pp
mvw
% R
em
ova
l HC
l, S
O2
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
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
% H
Cl R
em
ova
l
lb/M
MB
tu H
Cl E
mis
sio
n R
ate
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 above1600 lb/hr
17
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
% S
O2
Re
mo
val
SO2
lb/M
MB
tu
lb/hr Sorbent Injection Rate
SO2 Emissions Versus Sorbent Injection Rate
SO2 lb/MMBtu
SO2 MATS Limit
SO2 % Removal
18
QA Considerations for DSI
Evaluations (FTIR Testing)
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
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
pp
mvw
SO
2
Time
Comparison of Plant CEMS, FTIR SO2 Data
M320 SO2 CEM SO2
Average % Difference = 1.7%
20
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 vendor21
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 compared22
Final Data: NSR Curve of SO2
Removal with SBC vs Trona
23
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
Thanks for your attention
Any questions?
Thomas A. Dunder, Ph.D.
919.256.6242
www.trcsolutioons.com