Measuring trace elements during the December 2012 Callide Oxy-Fuel - - PowerPoint PPT Presentation

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Measuring trace elements during the December 2012 Callide Oxy-Fuel - - PowerPoint PPT Presentation

Mar 12, 2023 238 likes •468 views

Measuring trace elements during the December 2012 Callide Oxy-Fuel trial Peter Nelson a *, Anthony Morrison a , P. Sargent Bray a , Hugh Malfroy b , Rohan Stanger c , Chris Spero d a Graduate School of the Environment, Macquarie Unibversity, NSW,

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SLIDE 1

Measuring trace elements during the December 2012 Callide Oxy-Fuel trial

Peter Nelsona*, Anthony Morrisona, P. Sargent Braya, Hugh Malfroyb, Rohan Stangerc, Chris Sperod

a Graduate School of the Environment, Macquarie Unibversity, NSW, Australia, 2109 bMalfroy Environmental Strategies, 18/37 Nicholson Street, East Balmain, NSW, Australia, 2041 cFaculty of Engineering and Built Environment,,Newcastle University, University Drive, Callaghan,

NSW, Australia, 2308

dCS Energy/Callide Oxyfuel Services Pty Ltd, Level 2 540 Wickham Street, Fortitude Valley

Queensland Australia 4006

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SLIDE 2

Project Parameters

  • Examination of trace metal fate and concentration
  • Four coal feeds (Coal C, Blend 1, Blend 2, Coal M)
  • Combination of sampling:

– solids inputs and outputs (coal and ash) – at the stack exhaust (under both air and oxyfired conditions) – at various points of the CO2 Processing Unit (CPU)

  • Sampling targets:

– Mercury (using both sorbent traps and continuous analysis) – Other trace metals (As, B, Be, Cd, Co, Cr, Cu, Mn, Ni, Pb, Sb, Se, Zn) – Halides (HBr, HCl, HF, Br, Cl, F) – Particulates

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SLIDE 3

Stack, Ash and CPU Sampling

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SLIDE 4

Stack Sampling Methods

  • Sampling probes and collection trains

complied to the following standards where practicable:

– Metals : USEPA Method 29 – Halides : USEPA Method 26/26a – Particulates: Australian Standard 4323.2 – Mercury : USEPA Method 30b ( sorbent trap modified for measurement of Hg++)

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SLIDE 5

CPU Sampling Methods

  • Pressurised process stream
  • no sampling probes used
  • collection trains identical to

those on the exhaust stack

  • Continuous Tekran mercury

analyser:

– deployed at several locations within the CPU – parallel determinations of mercury using sorbent tubes

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SLIDE 6

CPU Sampling Locations

Blower Outlet Compressor Outlet Dryer Outlet Coldbox Outlet

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SLIDE 7

Outcomes

Halides: Location Air Oxy HBr

0.06-0.61 <0.10

HCl

10 - 67 9 - 18

HF

9 - 36 4 - 12

Br Cl F STACK <MDL <MDL <MDL (mg/Nm³) CPU <MDL <MDL <MDL <MDL <MDL <MDL (mg/Nm³)

*MDL Minimum Detection Limit for Method

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SLIDE 8

0.0 1.0 2.0 3.0 B Cr Mn Ni Zn mg/Nm³ 0.00 0.05 0.10 0.15 0.20 Cd Co Cu Pb Se mg/Nm³ Airfiring Oxyfiring The elements Sb, As, Be were below MDL under both air and

  • xyfiring conditions, Cd was below

the MDL under airfiring conditions.

Outcomes

All elements were at or around MDL values in the CPU beyond the first low pressure scrubber.

Metals:

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SLIDE 9

Summary of Outcomes

  • Halides and Metals – variations in stack gas

concentrations appear influenced by both firing method (oxy or air) and coal type;

  • Halides – detectable in stack gases; all species

below method detection limits beyond blower

  • utlet (i.e following initial low pressure gas

scrubbers)

  • Metals - elemental concentrations at very low

levels in the CPU at the blower outlet and beyond; often below method detection limits

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SLIDE 10

Mercury Mass Balance

Mercury analysis at the following stages of the process:

  • Coal Input
  • Ash Outputs (fly ash, bottom ash, rear pass and

air heater ash)

  • Flue gas concentration at stack
  • Process gas concentration in CPU

– Blower outlet – Compressor Outlet – Dryer Outlet – Coldbox outlet

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SLIDE 11

Coal feed stockpile

Hg in coal feed 22.9 -39.4 (ng/g)

5-13% 87-95% Slag & Ash 100%

Mercury Distribution Airfiring

Total mercury concentration in flue gas 0.1- 0.8 µg/m³

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SLIDE 12

UBC in Flyash (%)a

Location Air Oxy Coal C

4.4 1.0-2.6

Blend 1

10.6 4.0

Blend 2

6.0 3.5

Coal Mb

11.0 12.5

STACK

a Weighted averaged from 8 hoppers b Results likely to be sub-optimal due to failure of

coal swirler during testing period

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SLIDE 13

Coal feed stockpile

Total mercury concentration in flue gas 2.7-4.9 µg/m³ Hg in coal feed 22.9 -39.4 (ng/g)

23-33% 64-74% Slag & Ash 100%

Approx 80%

  • f flue gas Hg

to CPU removed at scrubber Total mercury concentration in process gas 0.4-0.9 µg/m³ Total mercury concentration in process gas <0.1 - 2 ng/m³

Mercury Distribution Oxyfiring(%)

2.0-2.9%

Approx 10% of total flue gas flow

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SLIDE 14

Mercury loss from CPU process gas

0% 20% 40% 60% 80% 100%

Flue Gas IN LP Scrubber Blower Compressor HP Scrubber Dryers Coldbox

CPU Process Operation Approximate Mercury Loss from Process Gas

Total mercury concentration in process gas <0.1 - 2 ng/m³ Total mercury concentration in flue gas input 2.7 - 4.9 µg/m³ Total mercury concentration in process gas 0.4 - 0.9 µg/m³

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SLIDE 15

Gas Phase Mercury Speciation

  • Estimations of Hg++ using KCl segments in sorbent traps;
  • Imperfect technique for Hg++ as some breakthrough in

the KCl occurred even at low sampling flow rates;

  • Will result in small underestimation of Hg++ ;
  • Total mercury estimation unaffected, negligible

breakthrough to second activated carbon segment ;

  • Total of 115 sorbent tubes analysed (71 stack, 34 CPU).

KCl segments (Hg++) Activated carbon segments FLUE GAS FLOW

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SLIDE 16

Averaged Ratio Hg++/Hgtotal

Location Air Oxy Blower Outlet Coal C

0.52 0.68

Blend 1

0.65 n.a.

Blend 2

0.47 0.68

Coal Ma

0.63 0.72

STACK CPU

0.08 n.a. 0.11 0.06

a Results likely to be sub-optimal due to failure of

coal swirler during testing period n.a not available

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SLIDE 17

Hg increases* following CPU depressurisation

TEKRAN LOG 12th Dec

10 20 30 40 50 60 70 80 00 02 04 07 09 12 14 16 19 TIME (HRS) Hg Concentration (ng/m³) Compressor Trip Compressor Restored

* Sampling location CPU compressor outlet

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SLIDE 18

Summary Hg outcomes

  • Hg was more likely to report to slag and ash under

air firing conditions, most likely a result of generally higher UBC (%) in flyash when air firing;

  • Ratios of Hg++/Hgtotal seem relatively unaffected by

firing condition (air or oxy);

  • Approximately 80% of Hg in CPU process gas was

removed by the initial low pressure scrubber;

  • Following depressurisation of the CPU, evidence of

significant Hg concentration increases was

  • bserved using the Tekran continuous Hg analyser;
  • Final CPU process gas Hg approached the levels

measured in ambient air (<2 ng/m³).

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SLIDE 19

Conclusions

  • Successful sampling campaign;
  • Initial analysis of data completed;
  • Minimal transfer of trace elements beyond

the first scrubber in the CPU;

  • Hg levels in CPU produced process gas

approach those measured in ambient air.

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SLIDE 20

Acknowledgements

  • The authors acknowledge the significant input to the

success of the project made by the sampling team from ECS Pty Ltd, Simon Newbigin, Michelle Yu, Henry Diona and Dante Mude.

  • The authors wish to also acknowledge financial

assistance provided through Australian National Low Emissions Coal Research and Development (ANLEC R&D). ANLEC R&D is supported by Australian Coal Association Low Emissions Technology Limited and the Australian Government through the Clean Energy Initiative.

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SLIDE 21

Outcomes

Metals:

Location Air Oxy

Blower Outlet Compressor Outlet Antimony <MDL <MDL Arsenic <MDL <MDL Beryllium <MDL <MDL Boron 0.60 - 1.11 1.22 - 2.03 0.004 - 0.011 Cadmium <MDL <0.006 Chromium 0.34 - 0.98 0.01 - 1.22 Cobalt 0.005-0.019 0.003-0.013 Copper 0.041-0.110 0.024-0.065 Lead 0.008-0.021 0.009-0.017 Manganese 0.085-0.390 0.097-0.375 Nickel 0.205-1.700 0.009-0.649 Selenium <0.015 <0.043 Zinc 0.073-0.410 0.047-0.172 <MDL <MDL <0.0013 <0.005 <0.006 <MDL <0.001 <MDL <0.002 <MDL <MDL 0.002-0.008 <MDL <MDL <MDL <MDL 0.003-0.010

CPU (mg/Nm³)

<MDL <MDL <MDL <0.0008 0.001-0.019 <0.0008 0.001-0.039 <0.001

STACK CPU (mg/Nm³) (mg/Nm³)

*MDL Minimum Detection Limit for Method

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SLIDE 22

Method Detection Limits

Stack CPU MDL (mg/dsm³) MDL (mg/dsm³) Halides HBr

0.038 - 0.077 0.016 - 0.033

HCl

0.19 - 0.39 0.082 - 0.17

HF

0.19 - 0.39 0.082 - 0.17

Br

0.031 - 0.077 0.016 - 0.033

Cl

0.15 - 0.39 0.082 - 0.17

F

0.031 - 0.077 0.016 - 0.13

Metals Antimony

0.0017 -0.0043 0.00055 - 0.00082

Arsenic

0.0042 - 0.0110 0.0014 - 0.0021

Beryllium

0.0017 -0.0043 0.00055 - 0.00082

Boron

0.0042 - 0.0110 0.0014 - 0.0024

Cadmium

0.0017 -0.0043 0.00055 - 0.00082

Chromium

0.0017 -0.0043 0.00055 - 0.00082

Cobalt

0.0017 -0.0043 0.00055 - 0.00082

Copper

0.0017 -0.0043 0.00055 - 0.00082

Lead

0.0017 -0.0043 0.00055 - 0.00082

Manganese

0.0017 -0.0043 0.00055 - 0.00082

Nickel

0.0017 -0.0043 0.00055 - 0.00082

Selenium

0.0043 - 0.0110 0.0014 - 0.0021

Zinc

0.0042 - 0.0110 0.0014 - 0.0021