determining the variability of continuous mercury monitors … · 2017-05-15 · determining the...

Determining the Variability of Continuous Mercury Monitors (CMMs) at Low Mercury Concentrations

with the Addition of Bromine

AIR QUALITY VIII, International ConferenceOctober 24–27, 2011Arlington, Virginia

Jeff Thompson, Dennis Laudal, John Pavlish, Chuck Dene

© 2011 University of North Dakota Energy & Environmental Research Center.

EERC . . . The International Center for Applied Energy Technology®

UW School of Energy Resources – Ms. Diana Hulme

Illinois Clean Coal Institute (ICCI) – Dr. Francois Botha

U.S. Department of Energy National Energy Technology Laboratory (DOE NETL) – Mr. Andrew Jones

Electric Power Research Institute (EPRI) – Mr. Charles Dene

Center for Air Toxic Metals® (CATM®) Affiliates Program – Mr. John Pavlish

Thermo Fisher Scientific – Dr. Dieter Kita

Tekran – Mr. Karl Wilbur

OhioLumex – Mr. Joseph SipersteinUniversity of Wyoming

Program Partners


Project Drivers

EPA Maximum Achievable Control Technology (MACT) Regulations – To meet regulations may require Hg control <1.0 µg/m3. Compliance verification cannot be effected without accurate and traceable low-level Hg measurements. It is expected that many of the plants firing a PRB coal would be required to use either brominated compounds or bromine-impregnated activated carbons.

Hg Abatement System Control – Accurate low-level Hg measurements are required to economically operate Hg reduction systems.

Hg Abatement Research – Low-level Hg measurements are required to properly assess new control technology performance. There is evidence that bromine in the flue gas can result in interferences biasing CMM results.


Project ObjectivesThe primary goal of the project is to determine the effects of bromine on the accuracy and precision of CMMs at mercury concentrations <1.0 µg/Nm3.

Verify the accuracy of carbon trap measurements via quadtrain sampling and spiked traps while sampling bromine-laden flue gas for mercury.

Determine the accuracy and precision of the CMM measurements while natural gas is burned, with mercury and bromine added under controlled conditions.

Determine the accuracy and variability of the CMM measurements while burning Wyoming PRB coal, with mercury control to levels <1.0 µg/Nm3.


Activity 1 – Initial Test Preparation.

Activity 2 – Pilot-Scale Tests on Natural Gas.

Activity 3 – Pilot-Scale Tests on Coal.

Project Activities


Mercury Measurement Methods

CMMsTekran Model 3300Thermo Scientific Freedom System

Sorbent trap method (EPA Method 30B), with traps to be supplied by OhioLumex

Directly analyzed using the OhioLumex RA-915+ mercury analyzer with PYRO-915 attachment


Tekran

ThermoScientific


Baseline Mercury Concentration Firing PTC on Natural Gas

Sample 1 Sample 2

Date

Time Sampled,

min

Hg onTrap,

ng

Measured Hg Conc., µg/Nm3

Hg on Trap,

ng

Measured Hg Conc., µg/Nm3

2/15/10 180 12.0 0.033 12.1 0.0344/26/10 240 19.3 0.033 19.3 0.033

4/27/10 240 13.9 0.024 14.7 0.024

4/28/10 240 16.0 0.022 14.0 0.021

4/29/10 240 8.9 0.014 10.6 0.015

5/24/10 240 35.4 0.088 44.7 0.085

5/25/10 240 17.6 0.037 15.2 0.035

5/26/10 240 12.2 0.025 11.1 0.025

5/27/10 240 9.9 0.021 10.2 0.021

Ambient Air Background Hg = 12 ng/m3 (0.012 µg/Nm3)


Tekran Thermo Scientific

SampleSorbent Trap,

µg/Nm3Sorbent Trap

µg/Nm3

1 0.483 1.1092 0.472 1.0773 0.484 1.0864 0.478 1.0575 0.481 1.0786 0.490 1.0807 0.482 1.077Average, µg/Nm3 0.482 1.081Set Point, µg/Nm3 0.500 1.000Mean Recovery, % 96.4 108.0RSD, % 1.8 3.9λ(95%), µg/Nm3 0.005 0.014

Calibrator Testing Results


Summary of Overall Results

Sorbent Trap Data, µg/Nm3 on a wet basis

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2

Tekr

an R

esul

ts, µ

g/N

m3 o

n a

wet

bas

is0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

1.1

1.2

Natural Gas - No SO2 and HClNatural Gas - with SO2 and HClIllinois Coal

R2 = 0.990


0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2

Ther

mo

Res

ults

, µg/

Nm

3 on

a w

et b

asis

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

1.1

1.2

Natural Gas - No SO2 and HClNatural Gas - with SO2 and HClIllinois Coal

R2 = 0.745


Software change: The auto calibration sequence initiated by the system did not update the reference intensity which is used in the lamp compensation routine. This was previously not detected as most of the systems in the field are zeroed and calibrated by the plant data acquisition systems. This zero offset was considered to be the main contributor to the high bias that occurred during the initial coal test.

Changes Made by Thermo Scientific for Repeat Coal Test


New system: Thermo Scientific used a system that had been used on several field studies. Upon the system’s return to Thermo, the analyzer was taken apart, and there was evidence of contamination in the optical bench.

Operated in total mercury mode only: It was clear that the Thermo Scientific CMM was not providing accurate speciation in the first coal test, so the repeat test was completed using only the total mercury settings and a 5– minute averaging cycle.

Changes Made by Thermo Scientific for Repeat Coal Test



0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2

Ther

mo

Res

ults

, µg/

Nm

3 on

a w

et b

asis

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

1.1

1.2

Natural Gas Test – No SO2 and HClNatural Gas Test – with SO2 and HClFirst Coal TestSecond Coal Test

R2 = 0.745 (using data from the first coal test)R2 = 0.911 (using data from the second coal test)

Summary of the Thermo Scientific Results for All Tests


Rel

ativ

e Ac

cura

cy, %

0

10

20

30

40

50

60

70

80

90

100

Natural Gas Tests First Coal Test Second Coal Test

Tekran CMMThermo Scientific CMM

Relative Accuracy Results Compared to the Sorbent Traps


Overall, the testing went well.

The baseline mercury levels when firing natural gas was fired were very low (at or near ambient mercury levels).

Both the Tekran and Thermo CMMs worked well on natural gas with and without the addition of the acid gases.

The Tekran has a lower detection limit than the Thermo system, although both were challenged during the baseline conditions (no mercury added).

The quad train sorbent trap results for all the tests provided a high level of precision.

General Observations and Conclusions


The calibrators used for both instruments were consistent and within 10% of the stated value.

Although there was some variability in the mercury emissions, the mercury concentrations were consistent over the time each quad train sorbent trap sample was taken.

When coal was fired, the Tekran appeared to match the sorbent results, but the Thermo system had a high bias.



After modifications were made to the Thermo Scientific CMM, the coal test was repeated, and the results were considerably better. The relative accuracy was 21.4% for the second coal test, compared to 67.3% for the first test.



Testing to evaluate the effects of bromine addition when measuring low level mercury concentrations. This project has the same partners except for the Wyoming Clean Coal Program rather than ICCI.

Future Testing


Activity 1 – Initial Test Preparation

Develop final test plan.

Obtain the Wyoming PRB coal and brominated activated carbon.

Ensure the spiking systems are operating properly.spiking of mercury into the combustor (10 µg/Nm3)

spiking of mercury into the flue gas downstream of the baghouse (0–1 µg/Nm3)

spiking of bromine (HBr) into the combustor (10 – 50 ppm)

spiking of bromine (HBr) into the flue gas downstream of the baghouse (0–5 ppm)

Obtain spiked and non-spiked sorbent traps

Setup of the two CMMs


Boiler Baghouse (BH)

Reduce Mercury concentration to <1.0 µg/Nm3

at the sample points.

System Configuration

ACInjection

HBrInjection


Test Condition

Spiked Hg Location

SpikedHg Conc. µg/Nm3

Type of Bromine

Used

Location of Bromine/AC

Injection

BromineInjection

rates1-a After BH 0.05 HBr Combustor 10 ppm*1-b After BH 0.05 HBr Combustor 50 ppm*2 Comb. 10 Brominated AC Upstream of BH 1-3 lb/macf

3-a Comb. 10 HBr + AC Comb./Upstream of BH 10 ppm3-b Comb. 10 HBr + AC Comb./Upstream of BH 50 ppm

Activity 2 – Pilot-Scale Tests on Natural Gas

* Flue gas concentration


TestCondition

Type of Bromine

Used

Location of Bromine/AC

InjectionBromine/AC

Injection rates4 None – Only AC Upstream of BH 3-5 macf5 Brominated AC Upstream of BH 1-3 lb/macf6-a HBr + AC Combustor/Upstream of BH 10 ppm6-b HBr + AC Combustor/Upstream of BH 50 ppm

Activity 3 – Pilot-Scale Tests on Coal


Activity 1 – All equipment works as planned.

Activity 2 – At mercury concentrations <1.0 µg/Nm3 both CMMs match the sorbent trap quadtrain data within 20% relative accuracy when firing natural gas and adding various forms of bromine.

Activity 3 – Same as two but firing a Wyoming PRB coal.

Success Criteria


Project Status

The testing phase (activity 2) of the project is scheduled to start next week with the natural gas testing. The WY coal test is scheduled for the week of November 14th.


Potential for Future Projects

Talks with HCl monitoring vendors has resulted in interest in tests to evaluate HCl monitors at the low levels of chloride expected when firing a PRB coal and with bromine present.


Disclaimer

This presentation was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States

Government, nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or

responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed or represents that

its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name,

trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States

Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United

States Government or any agency thereof.

determining the variability of continuous mercury monitors … · 2017-05-15 · determining the...

Documents