Material and ProcessMaterial and Process ConditionsConditions for Successful Usefor Successful Use of Extractiveof Extractive

Sampling TechniquesSampling Techniques

Presented by Barbara Marshik, PhD MKS Instruments, Inc.

Barbara_Marshik@mksinst.com

Presented at EPA Region 6 - 25th Annual Quality Assurance Conference October 21st, 2015

Acknowledgement

All of the testing and work as well as the EPA CEMs summaries presented here was performed by Roberto Bosco – Principal Applications Engineer at MKS Instruments, Inc. – In the Process & Environmental Analysis Solutions group

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Continuous Emissions Monitoring US EPA Clean Air Act

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Certifying Emissions Compliance Relative Accuracy Test Audit

3rd Party Stack Tester

Cal Line

Sample Line (191oC)

Emissions Testing Process

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Emissions Monitoring and Ratification by Extractive FTIR

Continuous Emissions Monitoring (CEM) – Continuous deployment in climate controlled hut

or enclosure

– Stack Emissions compliance recorded regularlyfollowing Governing body regulations (EPA, EU)

– Cement kiln, Power plants, Incinerators

Emissions Ratification (Stack Testing) – Transport equipment to site for Validation Test – Certifying emissions compliance

Demonstrate compliance based on site-specific air permit

Monthly, quarterly, biannually or yearly basis as listed on permit

Some Good Engineering Practices for On Site Certification Testing

Validate that the Analyzer is functioning properly – Follow Manufacturer’s requirements

Validate that the Sampling system is working properly – Make sure the wetted components are clean with no particulates – Perform a system Leak Test – Perform a system response test (spike recovery or other test)

Run the analysis – Zero and Span the analyzer – Perform pre-tests as required by regulatory agency – Run the Certification Test – Perform pre-tests as required by regulatory agency

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Sampling System Issues that Produce Errors in Analysis

ANY analyzer using extractive techniques experience these issues!!!

Sample gas recoveries are not within specification – Sampling system has a leak – all gases report low – Sample gas flow rate may be too low

Retention or Condensing of analyte components – Gaseous compounds may adhere to sample line, regulator,

filter, etc. Proper material selection is needed

– Gaseous Analytes can condense out of the vapor phase Cold spots in sample line or components Moisture in regulators and on lines

– Chiller will drop out polar analytes

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Sampling System Leak Test

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3rd Party Stack Tester

Spike Line (RT)

Sample Line (191oC)

Sampling System and Analyte Validation via Analyte Spiking

Reference Spike gas replaces 10% of sample gas

Compare Native concentration, added spike gas concentration to Analyzer value to get % Recovery

Retention or Condensing of Analyte Components

Reactive Gases – React with other gaseous species – React/adsorb with wetted materials – Water soluble – Examples: HCl, NH3, NO2, Formaldehyde, HF

Excessive response times – Failure to achieve acceptable t95 times – Inability to achieve the certified gas concentration

Failed concentration tests Failed spike tests

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Sampling System Considerations

Wetted Components – Calibration Gas Cylinder Pressure Regulator – Sample gas probe, heated sampling line, unheated calibration gas line – Analyzer internal wetted surfaces – FTIR gas cell

Sampling System Temperatures – Typical extractive sample line temperatures 191 °C – Some emissions tests allow lower temperatures ~120 °C

Typical Wetted Line Materials – HDPE – High-density polyethylene (max temp 110 °C ) – PTFE – Polytetrafluoroethylene (max temp 260 °C ) – PFA – Perfluoroalkoxy (max temp 260 °C ) – Stainless Steel coated with SilcoNert® or uncoated

Gas flow rate – Higher flow rates preferred (3 to 7 LPM)

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Pressure Regulator

Initial Regulator Installation – Back purge regulator with dry N2 – Install on tank while still purging

Pressure/Purge line – Close valve to probe, open gas

cylinder – Close gas cylinder valve, open

valve to probe – Repeat 10x

Best practice – Leave regulator on cylinder – do

not remove. – Do not use regulator on any other

gas component

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N2V-4

To Probe

HCl

 

 

   

    

Pressure Regulator NH3 Example

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0

1

2

3

4

5

6

0:00 0:05 0:10 0:15 0:20 0:25 0:30 0:35

NH3 [ppm

]

Time [HR:MN]

N2 Purge No Purge

Saturated at 70F Expected

NH3 On

20.0

New vs Old Pressure Regulator HCHO Example

SS-No N2 Purge SS-N2 Purge SS-Saturated at 70 F

0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

16.0

18.0

Expected HCOH On

0:00 0:10 0:20 0:30 0:40 0:50 1:00 Time [min]

15

 

 

             

   

      

New vs Old Pressure Regulator HCHO Example

0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

16.0

18.0

20.0

HCH

O [p

pm]

New Stainless Regulator 1 LPM 100’ PFA Line

SS‐N2 Purge SS‐No Purge

SS‐Saturated at 70 F Expected

HCHO On

0:00 0:05 0:10 0:15 0:20 0:25 0:30 0:35 0:40 0:45

Time [HR:MM]

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Gas Regulators What Did We Learn?

Water in the air can condense in regulator – It will absorb NH3, HF, HCl, NO2, and CH2O – SilcoNert® Stainless Steel coating

Reduces surface adsorption - Good HF reacts with coating - Bad

Prep required while installing regulator – Purge regulator with nitrogen for 15 to 30 minutes – Follow with Pressure Purging with cylinder gas 10x

Avoid using “used” regulators – Leave regulator on cylinder all the time – Once cylinder expires back purge with N2 while removing

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Calibration / Spike Gas Line Material Tests

Typical materials available – Stainless steel (SS) – High density polyethylene (HDPE) – Poly tetrafluoroethylene (PTFE) – Perfluoroalkoxy (PFA)

Line – ¼” Outside Diameter (OD) – 100 feet in length – Unheated

Flow rates of 1 to 3.5 LPM 18

 

  

 

Calibration Line Material 3ppm HCl @ 1LPM

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

HCl

[ppm

]

HDPE PFA PTFE Untreated SS HCl On

95%

Expected

0 15 30 45 60 75 90 105 120 Time [min] 19

Calibration Line PTFE 3ppm HCl @ Various Flows

HC

l [pp

m]

3.5

3.0

2.5

2.0

1.5

1.0

0.5

0.0

HCl On 1 LPM 2 LPM 3.5 LPM

Expected

95%

0 10 20 30 40 50 Time [min]

20

60

HC

l [pp

m]

Calibration Line Material 84 ppm HCl @ 3.5LPM

HDPE PTFE HCl On PFA Untreated SS

90 Expected

80

95% 70

60

50

40

30

20

0 2 2.5 3 3.5 4 4.5 5 5.5 6

Time [min] 21

10

 

 

   

Calibration Line HDPE HCl

[ppm

]

84 ppm HCl @ Various Flows 100

90

80

70

60

50

40

30

20

10

0

100’ HDPE

1 LPM 3.5 LPM

95%

HCl On

Expected

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Time [min] 22

 

 

 

NH3 [ppm

]

5

6 NH3 On

100’ Calibration Line 5ppm NH3 @ 1LPM

HDPE PFA PTFE Untreated SS

4

3

2

1

0 0:00 0:05 0:10 0:15 0:20 0:25

Time [HR:MM] 0:30 0:35 0:40 0:45 0:50 0:55 1:00

Expected

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NH3 [ppm

] Calibration Line Material

5ppm NH3 @ 3LPM HDPE PFA

6 NH3 On PTFE Untreated SS

5

4

3

2

1

0

Time [HR:MM]

Expected

0:00 0:05 0:10 0:15 0:20 0:25 0:30 0:35 0:40 0:45 0:50 0:55 1:00

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Calibration Lines What Did We Learn?

HPDE Lines work fine for all gases Flow matters

– Flow rate >3 LPM is good

For HCl - use higher concentration cylinders if possible and dilute

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Sample Line Material Test

Calibration / Spike Line Material – 100’ of HDPE - unheated

Sample Gas Line Material – 35’ - Heated to 191 °C – PTFE, PFA – Stainless Steel

Coated with SilcoNert® Uncoated

Flow rates of 1 to 3.5 LPM using low concentrations

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35’ Sample Line Tests ~5ppm NO2 at 191 °C

NO2 [ppm

]

6.0

5.0

4.0

3.0

2.0

1.0

0.0

Heated Sample Corrugated SilcoNert SS Corrugated SS PFA

NO2 On

Expected

Lines @191oC

100’ HPDE unheated Cal Line

0:00 0:10 0:20 0:30 0:40 0:50 1:00 Time [HR:MM]

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35’ Sample Line Tests 5ppm NH3 at 191 °C

NH3 [ppm

]

6

5

4

3

2

1

0

Corrugated SS Heated Sample Corrugated SilcoNert SS Lines @191oC PFA PTFE

Expected

NH3 On

100’ HPDE unheated Cal Line

0:00 0:07 0:14 0:21 0:28 0:36 0:43 0:50 0:57

Time [HR:MM]

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100’ Sample Line and Flow Tests on 3ppm HCl at 191 °C

PTFE/PTFE (2 LPM) PTFE/PTFE (3.5 LPM) HCl On

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

HCl

[ppm

]

HDPE/SS (2 LPM) HDPE/SS (3.5 LPM)

Expected

100’ Cal line @ 25oC 100’ Sample line @191oC

0:00 0:10 0:20 0:30 0:40 0:50 1:00 Time [HR:MM] 29

Heated Sample Lines What Did We Learn?

PFA and Silconert SS Lines work well for most gases

Flow still matters – Flow rate >3 LPM is good

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NH3 Response Testing Tests performed at University of Michigan – John Hoard

Published in SAE 2014-01-1586 “NH3 Storage in Sample Lines” Hoard, J., Venkataramanan, N., Marshik, B., and Murphy, B.

Test Parameters – Line Length

20 or 35 feet (6.09 or 10.7 meter) – Line Diameter

1/4 or 3/8 inch (6.35 or 9.52 mm) – Line Material

SS, SS Corrugated, SS Corrugated Siliconert coated, PFA – Temperature

113° or 191°C – Hydration Effect

Dry or Wet (~5% H2O) – Flow Rate

5, 10, 15, and 20 SLPM 31

Table of Material Components Diameter Sample Lines

35 feet lines

Line 1 SS Straight

Line 2 SS Corrugated Silconert

Line 3 SS Corrugated

1 / 4 “ Line 4 Per-Fluro Alkoxy (PFA)

20 feet lines

Line 5 SS Straight

Line 6 SS Corrugated Silconert

Line 7 SS Corrugated

35 feet lines

Line 8 SS Corrugated

3 / 8 “ Line 9 PFA

20 feet lines

Line 10 SS Corrugated Silconert

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NH

3 C

onc.

(ppm

)

Typical “up” Response (NH3)

25 30

25 20

20

NH

3 C

onc.

(ppm

)

0 50 100 150 200 250 300 350 400 450 500 0 20 40 60 80 100 120 140 160 180 200

15

10

15

10

5 5

0 0

Time (secs) Time (secs)

NH3 response of SS Straight line at 113 C 5lpm NH3 response of SS Straight line at 113 C 20lpm

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20

25

NH

3 C

onc.

(ppm

)

NH3 Storage / Retention Area

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NH

3 C

onc.

(ppm

)

0 50 100 150 200 250 300 350 400 450 500 0 20 40 60 80 100 120 140 160 180 200

25

20

15

10

15

10

5 5

0 0

Time (secs) Time (secs)

NH3 response of SS Straight line at 113 C 5lpm NH3 response of SS Straight line at 113 C 20lpm

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ANOVA Main Parameters that affect NH3 Storage

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Summary of NH3 Storage / Retention Effects

For transport and mixing: – Flow > 5 SLPM; 10-15 seems a good range – Line length and diameter had little effect in this range – The sample line type of material: corrugated is slower

With respect to NH3 storage/retention effects: – Length and diameter not very critical in this range – Corrugated line stores most NH3 straight line least – Can be offset by coating corrugated line with Silconert – Presence of water reduces NH3 storage – Higher temperature reduces NH3storage

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Line Material Summary

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Gas Calibration Line (25oC) Sample Line (191oC)

PTFE PFA HDPE Stainless Steel PTFE PFA

Stainless Steel

SilcoNert® SS

HCl Very Good Good Good Bad Very Good Very Good Bad Very Good

NH3 Good Good Very Good Bad Bad Good Good Very Good

HF Good TBD Good Bad Good TBD TBD Bad

HCHO Good Very Good Very Good Bad Very Good Very Good Very Good Very Good

NO2 Very Good Bad Very Good Bad TBD OK Bad Very Good

   

         

 

     

         

   

Sample Probe and Filter Material Summary

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Gas

Sample Probe Filter Material

Stainless Steel

SilcoNert® SS

PTFE Borosilicate

Glass Stainless Steel

SilcoNert® SS

HCl Good Very Good Good Good Bad Bad

NH3 Good Very Good OK Very Good Good Very Good

HF Good Bad Good Bad Bad Bad

CH2O Very Good Very Good Very Good Good Very Good Very Good

NO2 Bad Very Good Good Good Bad Very Good

Conclusions / Best Practices

Prep required while installing regulator – Purge regulator with nitrogen for 15 to 30 minutes – Pressure Purge line with cylinder gas 10x – Use new regulators, leave on the cylinder all the time

Calibration gas wetted surfaces – HPDE works fine for all gases

Sample gas wetted surfaces – Silconert coated line and probe best for all except HF – Borasilicate glass heated filter material best for all

except HF – For HF use PTFE heated lines and PTFE filters

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