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

tdunder@trcsolutions.com

www.trcsolutioons.com