Mercury (Hg) inMercury (Hg) inMercury (Hg) in Mercury (Hg) in OxyOxy--Coal Fired Power Plant with COCoal Fired Power Plant with CO22 CaptureCapture

What is the Real Score???What is the Real Score???What is the Real Score???What is the Real Score???

by

Stanley SantosIEA Greenhouse Gas R&D Programme

Cheltenham, UK

http://www.ieagreen.org.uk*Corresponding Author’s Email: stanley@ieaghg.org

AcknowledgementsAcknowledgements• Lesley Sloss (IEA Clean Coal Centre)

J t W dt (Ut h U i it )• Jost Wendt (Utah University)• Vince White (Air Products)• Minish Shah, Sho Kobayashi (Praxair)• Denis Cieutat Jean Pierre Tranier (Air Liquide)• Denis Cieutat, Jean Pierre Tranier (Air Liquide)• Rodney Allam• …

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Objectives of this PresentationObjectives of this Presentationjj• To provide awareness the impact / risk of ignoring

Hg in any Oxy-Coal Combustion Power Plant withHg in any Oxy Coal Combustion Power Plant with CO2 Capture

• To initiate discussion on the issue of Mercury in• To initiate discussion on the issue of Mercury in Oxy-Coal Combustion Power Plant

• To initiate a review on the different factors to reconsider on the design of coal power plant in the perspective of Hg.

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CO2 Compression and Purification System –Inerts removal and compression to 110 bar

Flue Gas Expander

Aluminium plate/fin exchangerFlue GasHeater

Flue Gas Vent

1 1 bar Expander1.1 bar20°C

25% CO275% 55°C75% inerts

-55°C

Driers

CO2 product110 bar

96% CO

30 bar Raw CO

96% CO24% Inerts-60°C dp

4

30 bar Raw CO2Saturated 30°C

76% CO2 24% Inerts

Case Study:Case Study:

M b G P i Pl t Fi I id tM b G P i Pl t Fi I id tMoomba Gas Processing Plant Fire IncidentMoomba Gas Processing Plant Fire Incident(01 January 2004)(01 January 2004)

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Safety Incident• Moomba Gas Processing Plant owned by Santos is the main

supplier of natural gas to South Australia and New Southsupplier of natural gas to South Australia and New South Wales○ Liquids separated from raw natural gas via 2 trains of LRP (Liquids q p g ( q

Recovery Plant)○ Liquids (condensate and LPG) sent to Port Bonython for export (about

650Km south of Moomba)650Km south of Moomba)

• About 02.43 in the morning, 1st January 2004 – an explosion & fire occurred at Train A of the LRP section& fire occurred at Train A of the LRP section.○ The fire incident also damaged Train B.

• Effect: liquids production interrupted for 8 months

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• Effect: liquids production interrupted for 8 months

Moomba Gas Processing Plant(L t)(Layout)

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Process Scheme of Liquid Recovery Plant

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Location of the Failure

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Failure Location

• Failure occurred at the base (6 o’clock) of the gas nozzle• Evidence of de-lamination consistent with Liquid Metal Embrittlement

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q(LME) caused by mercury in contact with aluminium

Other potential failure caused by HgFurther inspection of the cold box after the incident showedbox after the incident showed evidence of pitting to the aluminium surface in several parts of the heat exchanger.

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This is How Mercury attacksThis is How Mercury attacks the Aluminium

Figure 1: A small amount of mercury attacking an aluminium beam in less than an hour

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[courtesy of Popular Science website].

Discussion PointsDiscussion PointsDiscussion PointsDiscussion Points

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Understanding Failure Mechanisms• Failure Mechanisms

○ Amalgamation○ Amalgam Corrosion○ Amalgam Corrosion○ Liquid metal embrittlement○ Galvanic Corrosion

• Factors that could increase the probability of failure are:○ Hg accumulation (i e due to shut down and process upsets)○ Hg accumulation (i.e. due to shut down and process upsets)○ In addition to the presence of mechanical and thermal stress, and○ moisture

• Accumulation would not occur under normal operating condition (i e -40oC and below)

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condition (i.e. 40 C and below)

Understanding Failure MechanismsUnderstanding Failure Mechanisms

• Statement from ALPEMA:• Statement from ALPEMA: In general, mercury will not react with aluminium unless it is allowed to exist in contact with the heat exchanger in its li id t t d th i t t If th ditiliquid state and there is water present. If these conditions exist within a heat exchanger, then mercury contamination can result in problems. This attack is most severe when pcoupled with another corrosion process.

• QUESTION #1: How dry do we need to go?

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Understanding Failure Mechanisms

• Known failures of BAHX due to mercury attack (i.e. Algeria, y ( g ,Thailand, Australia) are random events!!!

• Statement from UOP Background Paper:Since the level of mercury that can be tolerated is not established, most operators want to remove it “all ” That is remove it to a level where itoperators want to remove it all. That is, remove it to a level where it can not be detected with the available analytical capability. Currently, this means reducing the mercury to less than 0.01 μg/Nm3.

• QUESTION #2: Is the 0.01 μg/Nm3 to be used as well in the oxy coal combustion power plant?

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well in the oxy-coal combustion power plant?

What are the Concerns???What are the Concerns???• Mercury from LNG plant are mostly elemental Hg

and some organo Hg speciesand some organo-Hg species.○ There are no technical barrier in removing mercury. This

is achieved by using Activated Carbon Bed or otheris achieved by using Activated Carbon Bed or other adsorbent.

I C l Fi d C H ill i th f f• In Coal Fired Case, Hg will come in the form of elemental Hg (as particulates or vapour) or Hg2+

( tl i th f f H Cl )(mostly in the form of HgCl2)• QUESTION #3: What is the speciation of Hg in an

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oxy-coal combustion cases?17

Fate of Mercury During Oxy-CombustionPossibility of most mercury dumped in the CO2 clean up process

Conversion of Hg to HgConversion of Hg to Hg2+2+

• Clearly established in Air Fired Cases that the benefits of co removal of Hg with FGD and SCRbenefits of co-removal of Hg with FGD and SCR are due to conversion of Hg (elemental) to Hg2+

• Correlation with Cl content of the coal is well established – this promote conversion to Hg2+

• Question #5: What will be the rate of conversion from Hg to Hg2+ in oxy-combustion case?g g y

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Impact of SOImpact of SO33

Data from ANL Studies (1980s)Data from ANL Studies (1980s) Black Thunder CoalBlack Thunder CoalData from ANL Studies (1980s) Data from ANL Studies (1980s) -- Black Thunder CoalBlack Thunder Coal

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U i ität St tt t

Measured SO3 concentrations for Lausitz coalat AIR and OXYFUEL combustion conditions Universität Stuttgart

SO3 measured,ppm

at AIR and OXYFUEL combustion conditions

120

140

ppm

OXYFUELSO2 SO3

80

100

120 measured measured

ppm ppm

60

80AIR 733 8 (6 – 11)*

OXYFUEL 1758 85 (36 – 121)*

20

40AIR

00 500 1000 1500 2000 2500

SO t t itiSO2 at measurment position, ppm* ... min. / max. value measured

Impact of SO3 on Hg Removal Efficiencyg yAir Fired Case (CODEN Study) Oxy Fired Case

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Mercury Management in the CO2 Processing Plant

• No technical barrier in removing Hg. This has been done in LNG industry The consideration of cost isdone in LNG industry. The consideration of cost is the main question!

• There are 3 levels where Hg (both elemental and ionic) could be captured in the CO processingionic) could be captured in the CO2 processing plant.

Compression stage○ Compression stage○ Moisture Removal stage

Activated Carbon Guard bed

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○ Activated Carbon Guard bed

CO2 Compression and Purification System –2Removal of SO2, NOx and Hg

SO2 removal: 100% NOx removal: 90-99%1.02 bar

30°C67% CO28% H2O

30 bar to DriersSaturated 30°C

76% CO28% H2O25% InertsSOx

224% Inerts

BFW15 bar

Water

NOx BFW

Condensate

30 barcw

cw

cw

Dilute H2SO4

Dilute HNO3

24

2 4 HNO3

Hg

NG Industry Practice (Data from Calgon 1996)(Data from Calgon 1996)

• Activated Carbon bed is generally employed This isgenerally employed. This is expected to be applied to oxy-combustion oxy-PC as y ywell.

• It is important to be aware with regard to short term performance drop of the activated carbon bed during h t d t

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shut down or process upset.

Mercury Sorbent Technologies (From M. Wilhelm, 1995 – Mercury Technology Services)( , y gy )

Q ti 7 Wh t ibl i t fQuestion 7: What are possible impact of NOx and Oxygen to these substrates?

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Hg Cleaning Process Environmental ConsiderationEnvironmental Consideration

• It should be expected that future environmental regulation would require recovery of Hg and back torecovery of Hg and back to the commercial cycle!

• Question #8: Can we recover Hg from therecover Hg from the wastewater sludges, ash bin and other sink etc...

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bin and other sink etc...(M. Wilhelm, 1995)

Mercury Analysis Method(From M. Wilhelm, 1995 – Mercury Technology Services)(From M. Wilhelm, 1995 Mercury Technology Services)

• Colorimetric 2000 ng• X Ray Flourescence 10 ng• X-Ray Flourescence 10 ng• Neutron Activation 2 ng

G ld Fil 0 5• Gold Film 0.5 ng• Differential Pulse Voltametry 0.04 ng• Cold Vapor Atomic Absorption 0.01 ng• Cold Vapor Atomic Flourescence 0.0001 ng

Question #9: Can we really measure mercury at the

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very low level?

The Real Score…The Real Score…

• What is the real issue?○ The real issue is how much Hg we are

delivering to the CO2 processing unitg p g○ What type of Hg species we are introducing

to the CO2 processing unit?to the CO2 processing unit?○ What is the most cost effective way of Hg

l t b i l d d i thremoval process to be included in the power plant?

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