biapws 2014 power plant chemistry symposium highlights

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Highlights of the BIAPWS 2014 Power Plant Chemistry Symposium

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INTRODUCTION

The 15th Power Plant Chemistry Symposium, organised bythe British and Irish Association for the Properties of Waterand Steam (BIAPWS) and supported by the Royal Societyof Chemistry (RSC) Water Sciences Forum, was held on2–3 April 2014 at the Village Hotel, Nottingham. Thismarked the return of the event after an absence in 2013due to BIAPWS involvement in co-hosting the 16th

International Conference on the Properties of Water andSteam (ICPWS16) on behalf of the International Associa -tion for the Properties of Water and Steam (IAPWS).

The Symposium consisted of introductory sessions on thefundamentals of plant preservation and closed circuitcooling water chemistry, which were targeted at develop-ing chemists and new entrants to the industry, followed bymore detailed technical presentations on 'Power PlantChemistry and Corrosion' and 'Environmental and WaterTreatment Issues'.

Through contacts made via IAPWS, the opportunity wastaken to invite guest speakers from across Europe to pro-vide additional perspectives on power plant chemistryexperiences and developments.

The event was very well attended, with close to one hun-dred delegates for both days (Figure 1). This demon-strated both the continued interest in developments incycle chemistry and water treatment and the networkingopportunities offered by the event. The proceedings of thesymposium are summarised in this report.

POWER PLANT CHEMISTRY FUNDAMENTALS

Power Plant Preservation Thomas Walsh, RWE npower, and Peter Hanney, EDFEnergy

Thomas Walsh reviewed the underlying corrosion princi-ples and mechanisms relevant to the preservation ofpower plants. The factors influencing localised pitting,crevice corrosion and dew point corrosion were dis-cussed. The importance of the corrosion triangle (elec-trolyte, material and environment) was explained in that itis only required to remove one of the three factors to effec-tively control corrosion. The different corrosion mechan-isms involved in general and localised corrosion wereexplained and the application of electrode potential versuscurrent density diagrams was emphasised to understandthe corrosion potential of different materials. The presen-tation finished on discussing the two principle ways ofpreserving plants, i.e. dehumidification or nitrogen cap-ping. Other options such as filming amines were alsomentioned.

Peter Hanney gave the second part of the preservationpresentation and detailed how the underlying corrosionfundamentals discussed previously can be applied toactual power plant preservation. Case studies from theEDF Energy nuclear fleet were used to demonstrate whatcan realistically be achieved. Examples were provided ofwhat can go wrong if plant is not preserved effectively.Having senior management "sign on" to the preservationprogramme was stressed. The importance of identifyingall plant areas that require preservation was discussed

Highlights of the BIAPWS 2014 Power Plant ChemistrySymposium

© 2014 by Waesseri GmbH. All rights reserved.

ABSTRACT

The British and Irish Association for the Properties of Water and Steam (BIAPWS) held its annual Symposium on PowerPlant Chemistry on 2–3 April 2014 in Nottingham. Summaries of the event proceedings are provided. The Symposiumconsisted of introductory sessions on the fundamentals of plant preservation and closed circuit cooling water chem-istry, followed by presentations on 'Power Plant Chemistry and Corrosion' and 'Environmental and Water TreatmentIssues', which included a case study of poor steam quality as a result of boiler water carryover at a new plant, theapplication of film forming amines and the environmental consenting of a new build nuclear power plant in the UK.

Paul McCann and Mark Robson

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since missing even a small bit of plant can be critical if itcan cause a single point of failure. During outages, theimportance of deciding when to remove preservation fornuclear plants was also highlighted in case outages over-run (on occasions, it has been necessary to extend outages by a number of weeks or even months). This isparticularly important at nuclear plants due to the planningand time required to implement preservation measures.Premature removal of preservation measures can exposecomponents to a corrosive environment with potentiallyserious consequences. The local environment also has tobe taken into account in assessing corrosion risks, partic-ularly if the plant is located in a coastal environment withgreater risk of salts being present.

Closed Circuit Cooling Water ChemistryStephen Turgoose, Intertek, and Alan Pomfret, GE Power& Water

Stephen Turgoose reviewed the underlying principles oflow temperature corrosion and the use of corrosioninhibitors in closed cooling water systems. The presenta-

tion began with a discussion of the various types of cool-ing water systems (i.e. open and closed) and the differentissues and inhibitor types for these systems. This was followed by a discussion of the various factors which influ-ence the effectiveness of corrosion inhibitors and how thecritical inhibitor concentration varied with these parame-ters. The importance of maintaining the correct level ofinhibitor was discussed in relation to the inhibitionmechanism and synergistic effects of multi-componentcorrosion inhibition products. The impact of corrosionproducts and existing corrosion on the required level ofinhibitor was discussed. This included the little appreci-ated fact that once you have corrosion or corrosion prod-ucts in a system, it is very difficult to predict what concen-trations of corrosion inhibitors are necessary to mitigateagainst further corrosion from this point.

Alan Pomfret introduced the concept of the water treat-ment "triangle" when treating a closed cooling water sys-tem where the three competing factors of corrosion,deposition and biological control all need to be consid-ered. The considerations needed when different metalsand polymers are present were outlined and how this

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Figure 1:

Symposium proceedings.


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varies depending on the type of water used in the system.A comprehensive list of the different types of inhibitorswas presented and a number of the more common groupswere discussed in detail. Particular emphasis was placedon the application of different classes of biocides to treat-ing closed cooling systems and their effectiveness at con-trolling different types of microbiological contamination.The importance of a monitoring programme to assess theeffectiveness of the control regime was discussed andsome typically acceptable corrosion rates and contamina-tion levels were presented.

POWER PLANT CHEMISTRY AND CORROSION

Boiler Water Carryover and Poor Steam Quality at NewPlantAndrew Mosley, RWE npower

Commissioned in 2010, the Staythorpe combined cyclegas turbine (CCGT) power station is owned and operatedby RWE npower in the UK. The station consists of 4 x425 MW single shaft units. The heat recovery steam generators (HRSGs) in each unit are of triple-pressurerecirculating drum-type design, with each drum independ-ently fed. Steam/water cycle chemistry is based on feed-water conditioning with ammonia and boiler water condi-tioning with tri-sodium phosphate.

During commissioning, the following problems with poorsteam and feedwater purity were identified in all four of theunits:

• Elevated feedwater dissolved oxygen concentrations;

• Persistent elevated steam and feedwater after cationconductivities;

• Elevated sodium in steam concentrations;

• Prolonged times to reach steam purity for start-ups.

The main cause of problems with steam purity was boilerwater carryover into the steam. This occurred mainly dur-ing load changes and start-ups, but with carryover ratesalso increasing with unit load. The carryover problemsmainly affected the low pressure drums, with spikes insteam sodium concentrations regularly recorded well inexcess of 100 µg · L–1 (Figure 2).

During commissioning, high levels of make-up water werebeing used as a result of various system leaks. Thiscaused the elevated levels of dissolved oxygen in thefeedwater, whilst the presence of carbon dioxide in themake-up water was largely responsible for the elevatedfeedwater and steam after cation conductivities. Theseissues have been resolved by fixing the leaks to reducemake-up water demand.

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Spikes in LP steam sodium concentrations as a result of boiler water carryover.



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The problems with drum carryover have been much moredifficult to address. Carryover risks were initially managedby reducing the phosphate concentrations targeted in thelow-pressure (LP) and intermediate-pressure (IP) boilers,not dosing phosphate during start-ups and not dosingphosphate at all to the high-pressure (HP) boilers.Changes to normal drum working levels were also tested,but these had no noticeable effect.

Consequently, it has been necessary to make significantmodifications to the original LP drum furniture to improvesteam separation by changing the design to reduce the LPevaporator riser pipe exit velocities and by directing thereturn flows away from the roof of the drum. Early indica-tions are that the LP drum modifications have resulted in asignificant reduction in carryover rates, though steampurity remains to be fully validated.

At-Temperature ORP Optimisation in a Two-ShiftingPower Station – Cause and EffectShauna Concannon, ESB Energy International

At ESB's 400 MW Coolkeeragh CCGT power station, astudy has been completed to optimise the cycle chemistryprogramme to mitigate flow-accelerated corrosion (FAC).

Coolkeeragh has a triple-pressure, vertically tubed, drum-type HRSG. As the LP circuit includes a combined LPdrum/deaerator, the feedwater is only dosed with ammo-nia, whilst the HP and IP boiler waters are conditionedwith tri-sodium phosphate.

As well as evidence of FAC, the station has also had prob-lems with high levels of iron transport, which has causedproblems with the operation of the IP feedwater controlvalve due to blockages. Consequently, the chemistryimprovement project was initiated. A number of optionshave been tested, with the effectiveness of each changeevaluated using At-Temperature Oxidation ReductionPotential (AT-ORPTM) and particle monitoring equipmentinstalled at the condensate and IP economiser inlet andoutlet sample points.

Initial monitoring showed the AT-ORP to be highly reduc-ing at all three locations (condensate –400 to –450 mV; IP economiser inlet and outlet –600 to –650 mV; referenceelectrode Ag/AgCl 0.1 N KCl), with on-line monitoring dataalso confirming very low level dissolved oxygen levels inthe condensate and feedwater (< 5 µg · L–1). Therefore, thefirst change made was to increase oxygen levels in the IPfeedwater by reducing the effectiveness of deaeration andthen by introducing oxygen directly into the condensate.However, neither change had any effect on the IP feed -water AT-ORP, though a correlation was seen betweencondensate AT-ORP and oxygen levels.

In the next stage of testing, the target condensate pH25was increased to 9.8. This resulted in a clear reduction incorrosion product transport at the IP economiser inlet, butmade little difference to the AT-ORP at this location. Also,the station had practical difficulties in using the 10 %ammonia solution that was needed to achieve the targetpH. A blend of monoethanolamine and ammonia was thentrialled with the aim of increasing the LP evaporator waterphase pH, but this resulted in high steam after cation con-ductivities.

The next phase of the programme returned to increasingoxygen levels in the IP feedwater, this time by the directinjection of air into the feedwater, rather than into the con-densate. This resulted in an immediate and significantincrease in the IP economiser inlet AT-ORP value fromapproximately –650 mV to –150 mV. In contrast, the AT-ORP at the IP economiser outlet took some time toincrease to –150 mV, showing that dissolved oxygen wasbeing consumed, probably as the internal oxides changedwith the presence of oxygen.

At the current stage of the optimisation, the changesmade have already had clear benefits for the station. Ironsampling has shown a significant reduction in corrosionproduct transport and there have also been distinctimprovements in the condition of the internal oxides in allthree boiler drums.

Properties and Application of Film Forming Amines forWater/Steam Cycle TreatmentWolfgang Hater, ICL Water Solutions

Boiler water treatment with film forming amines involves acombination of pH adjustment by the use of alkalisingamines and protection of the complete system due to filmformation by amines such as Cetamine®. Some film form-ing amine formulations may also use polymers for the dispersion of solids.

In developing Cetamine technology for power plant appli-cations, ICL has completed research both in-house and incollaboration with universities and industrial partners todemonstrate product performance. This has shown thefollowing:

• Magnetite layer stabilisation. A shell boiler simulationshowed much smoother and homogeneous surfaceswith Cetamine in comparison to the use of tri-sodiumphosphate [1]. The use of Cetamine in a 90 bar paperindustry water tube boiler showed much reduced oxidegrowth in comparison to ammonia and phosphatetreatment.

• Improved heat transfer in a shell boiler simulation incomparison to phosphate treatment [2].



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• Minimal effect on resins in a condensate polishing unitafter six years of operation with Cetamine.

• Development of photometric laboratory and on-linemethods so that film forming amine concentrations canbe measured directly [3].

• Tests carried out with SWAN Analytical Instruments inwhich the compatibility of Cetamine with pH, conduc-tivity, sodium and silica on-line sensors was demon-strated, though use resulted in a loss of sensitivity andreduced speed of response with ORP sensors [4].

Two case studies were presented on the use of Cetaminefor the treatment of the steam/water cycle at E.ONThüringer Energie's Jena combined heat and power (CHP)plant and for the dry preservation of the brown-coal-firedpower plant.

E.ON's Jena CHP has three HRSGs that operate at a pres-sure of 9.8 MPa with a final steam temperature of 510 °C.Initial steam/water cycle conditioning was with ammoniaand hydrazine; however, the local authority required thesubstitution of hydrazine, with Cetamine chosen as thereplacement. Since use, the results of most chemicalmeasurements have not changed, with iron and copperlevels remaining below the analytical detection limit. Anelevation in steam after cation conductivity from< 0.2 µS · cm–1 to 0.8 µS · cm–1 was seen, so that addi-tional degassed after cation conductivity analysers wereinstalled, with readings typically of 0.3 µS · cm–1. Furtheranalysis showed a contribution to the steam after cationconductivity of 0.5 µS · cm–1 from carbon dioxide and0.2 µS · cm–1 from acetate.

At the brown-coal-fired power station, dry preservationwith the original oxygenated treatment was not satisfac-tory because the unit could not be completely drained andthe plant was not equipped for nitrogen blanketing (plantre-engineering was considered too expensive). On returnto service, the cycle chemistry took approximately 35hours to return within normal targets and high iron levelswere measured. To improve plant preservation, it wasdecided to dose Cetamine instead of ammonia for aperiod of one month before shutdown. With this approach,visual inspections showed the system remained free fromcorrosion and deposits during preservation (note that thesteam turbine was preserved with dry air). On return toservice, the cycle chemistry was within normal targetswithin only 12 hours.

Thermal Decomposition of Alkalising Amines at Super -heater ConditionsDavid Moed, TU Delft

Despite the relatively wide use of organic alkalising aminesin power plant steam/water cycles, there remains a needfor comprehensive data to be produced on their thermalstability and degradation kinetics. Consequently, DelftUniversity of Technology (TU Delft) has started tests in aflow reactor towards developing a kinetic model for thebreakdown of morpholine (MOR), monoethanolamine(ETA), dimethylamine (DMA) and cyclohexylamine (CHA)under typical boiler (352 °C/17.5 MPa) and superheater(470 to 510 °C/17.5 MPa) conditions.

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Variables investigated so far have included temperature,pressure, time and wall effects. In the tests, amine andorganic acid concentrations were measured by ion chro-matography.

The first stage of the test work investigated amine degra-dation kinetics as a function of typical boiler and super-heater temperatures and pressures. These tests showedthe following results:

• The order of thermal stability was CHA > DMA > MOR >ETA.

• Decomposition followed first order kinetics nicely(Figure 3).

• Degradation can be rapid at superheater temperatures.

• The potential for degradation to acetate and formatedepends on the amine structure.

• Formate itself was not stable.

• Tests with MOR showed stability increasing with pres-sure for a given temperature.

The second stage of the test work investigated the influ-ence of wall effects on amine decomposition by complet-ing tests using tubing with different surface area to volumeratios at approximately superheater temperatures (500 to530 °C). This showed that wall effects have a large influ-ence on decomposition kinetics, with higher rates ofdegradation measured in smaller bore tubing. This sug-gested that decomposition kinetics were overestimated inthe first stage of the study.

There remain a number of other possible variables to beconsidered in the tests. In the next stage of the study, it isproposed to investigate pressure and temperature rela-tionships further and also the possible influence of heatflux on wall effects.

The contribution of the Electric Power Research Institute(EPRI) and Evides Industriewater as project sponsors wasgratefully acknowledged.

ENVIRONMENTAL AND WATER TREATMENTISSUES

Seveso III Directive and New COMAH Regulations2015 – An UpdateChristina Roberts, Health and Safety Executive

The EU Seveso III Directive on the control of major accidenthazards involving dangerous substances was published on24 July 2012. The new Directive is necessary as EU chemi-cal classification legislation is being changed by 2015. Theoverall purpose and approach of the Directive remains thesame as previously (i.e. identification of relevant sites, con-

trols and mitigation), but with changes primarily to require-ments for public information and participation.

In the UK, the Seveso III Directive will come into force from1 June 2015. The Directive is implemented through theControl of Major Accident Hazards (COMAH) regulationsand planning legislation.

At present, there are around 1 000 sites in the UK that cur-rently fall under the COMAH regulations. Under Seveso III,the number of sites affected is expected to largely remainthe same and the current system for site inspections haslargely been maintained. Changes to the new Directive willrequire public information to be made available on safetymeasures for all COMAH sites, whereas currently publicinformation is only required for Top Tier sites. However,there are provisions within the Directive to address greatercommercial confidentiality and national security issueswhen making information publicly available.

The scope of the Directive has changed from 10 CHIP cat-egories (chemicals hazard information and packaging forsupply regulations) to 16 CLP categories (classification,labelling and packaging), with some amendments to sub-stances of relevance to power plant activities. Thisincludes the addition of sodium hypochlorite and anhy-drous ammonia as named substances. Heavy fuel oil(HFO) has been reclassified in the 'petroleum products'category instead of remaining in the 'dangerous to theenvironment' category, which has changed the qualifyinginventories that may be stored on site.

The classification of hydrazine will remain the same withqualification only if solutions are stored on site at concen-trations above 5 percent by weight.

Where dangerous substances are present in amountsequal to or less than 2 percent of the relevant qualifyingquantity, these can still be ignored when determining thetotal quantity present if they are separated such that theycannot act as a major accident initiator.

Environmental Permissions for Hinkley Point C:Chemical and Ecological PerspectivesRoss Pettigrew, EDF Energy

Hinkley Point C (HPC) is EDF Energy's proposed 2 x1 650 MW UK EPR® (a pressurised water reactor byAREVA) nuclear power plant development situated on theSevern Estuary. The site is considered to be suitable fornew nuclear development for various reasons, includingthe proximity to existing nuclear power stations, access tocooling water, existing grid infrastructure, location mainlyoutside designated areas of ecological importance, pro-tection from coastal flooding and ability to utilise existingroads for site access.



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As part of the project development process, various envi-ronmental and operational permissions are required forthe site. These include:

• Generic Design Assessment Statement of DesignAcceptability for the UK EPR;

• Nuclear Site Licence;

• Development Consent Order;

• Construction-related environmental permits and con-sents;

• Commissioning-related environmental permits (effluentdischarges);

• Radioactive Substances Regulation EnvironmentalPermit;

• Combustion Activity Environmental Permit (operation ofemergency diesel generators);

• Operational Water Discharge Activity EnvironmentalPermit (discharges of cooling water and chemical efflu-ents);

• COMAH registration (lower tier site);

• Hazardous Substances Consent (planning require-ment);

• Marine licences.

At HPC, the use of once-through cooling is considered torepresent best available techniques (BAT) for the site (sub-ject to implementation of various aspects of design). Aspart of the environmental permitting for the cooling watersystem, various fish protection measures have beenincluded in the design evolution in order to meet the con-servation objectives for the site. These include:

• Designing the intake to minimise fish capture by con-sideration of intake location in the estuary, reducinginflow velocities, drawing water in horizontally and orientation of the intake screens so that the inflowdirection is perpendicular to the main tidal currents;

• Installation of an acoustic fish deterrent (AFD) system atthe intake;

• Drum screens designed to assist fish recovery, includ-ing 5 mm mesh size with profiling to avoid sharp orabrasive surfaces;

• Fish return system using Archimedes screws to min-imise damage to fish.

In determining BAT for the HPC cooling water system, theframework set out in the UK Environment Agency's guid-ance document "Cooling Water Options for the NewGeneration of Nuclear Power Stations in the UK" was fol-lowed [5]. In this document, best practice for cooling

water system design and approaches for minimising envi-ronmental impacts are described.

To satisfy environmental permitting conditions, additionalwork is also being undertaken on hydrazine discharges towater. In the EPR design, hydrazine is used in the primaryand secondary circuits as an oxygen scavenger. However,hydrazine in the secondary circuit may be discharged intothe conventional island effluent tanks. Consequently, efflu-ent treatment options to remove hydrazine are beinginvestigated (e.g. hydrogen peroxide injection, catalyticremoval), as well as analytical techniques for hydrazine tosupport environmental monitoring of the treated effluent.

Reducing Power Station Water Demand by Treatmentof River WaterJulian Gibson, Ondeo Industrial Solutions

At EDF Energy's recently commissioned West Burton 3 x430 MW CCGT power station, water from the River Trentis treated for use as make-up for the cooling water systemand as feedwater for the boiler make-up water demineral-isation plant. The water treatment plants were designedby Ondeo Industrial Solutions and were commissioned in2013. The treatment plants are now operated by OndeoIndustrial Solutions UK on behalf of EDF Energy.

One of the main purposes of the treatment process is toreduce calcium hardness and suspended solids levels inthe river water so that it can be cycled up in the coolingwater system to achieve a concentration factor of approx-imately 2.5–3.0 in order to reduce site water usage andenvironmental footprint.

Densadeg® technology was selected as a key part of theinitial treatment process. To achieve the required treatedwater quality and quantity, the Densadeg plant is based on3 x 800 m3 · h–1 lines of lime softening, coagulation andflocculation. Sludge dewatering from sedimentation is byfilter press. For boiler make-up water production, thetreated water from the Densadeg process is passed to ademineralisation plant consisting of 2 x 50 m3 · h–1 lines ofion exchange treatment.

At West Burton CCGT, water treatment and control of thetreatment process is complicated by the river water qualityand power plant unit operation at the site. The river waterquality is variable, with calcium hardness concentrations of125 to 450 mg · L–1 as CaCO3, whilst suspended solidsconcentrations can be anywhere between 20 to1 900 mg · L–1. Furthermore, the power plant units areoperated flexibly, with frequent start-ups and shutdowns,such that water demand can also be highly variable.

Early operation has shown that the Densadeg plant provides robust treatment to provide good quality make-

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up water for the cooling system. Typical treated waterquality includes a reduction in calcium hardness to150–200 mg · L–1 as CaCO3 and a reduction in suspendedsolids concentrations to consistently less than 2 mg · L–1.However, it has been necessary to retrofit reverse osmosistrains at the outlet of the demineralisation plant in order tofurther reduce the total organic carbon (TOC) content.

With the variable operation of the power plant units, theDensadeg plant often operates in recycle mode to main-tain stable operation. To maintain satisfactory treatedwater quality, flow prediction software has been devel-oped based on advance notification of power plant unitoperation so that Densadeg water production rates can beramped up and down at the required design rate.

Due to the variable river water quality and water demand,the Densadeg plant is manned continuously by shift teamsto maintain satisfactory performance. Daily jar tests arecompleted so that chemical dosing can be adjusted tooptimise Densadeg operation for the river water condi-tions on any given day.

Handling Serious Sea Water Contamination of theWater/Steam Circuit of a Once-Through BoilerKarsten Thomsen, COWI A/S

In February 2012, a condenser leak occurred during thestart-up of the once-through (Benson type) coal-firedboiler unit AMV3 at Amagerværket in Copenhagen whichresulted in major contamination of the steam/water cycle.The cause of the leak was mechanical damage to the con-denser.

The plant has a titanium condenser, so the leak was unex-pected. The discovery of the leak was also delayed due totechnical problems during the start-up and the responsetime of the on-line chemical monitoring instruments. Theinitial leak could not be contained due to the design of thecondenser with a split hotwell (condensate flows fromdirty side to the clean side) and the design of the conden-sate polishing plant to only treat 8 % of the condensateflow. Consequently, feedwater with an after cation con-ductivity of approximately 300 µS · cm–1 entered the boiler.

In the first week after the contamination, initial flushingand draining from the condensate and feedwater trainswith the boiler in bypass operation was able to improvewater quality to achieve the criteria necessary for steamturbine operation. However, load increases with the boilerin recirculation mode and the steam turbine in serviceresulted in salt releases. When the boiler load was thenincreased past the Benson point, there was a large andrapid increase in steam after cation conductivity to above14 µS · cm–1 before a gradual fall over a couple of weeks toaround 0.1 µS · cm–1. These effects showed that the con-

tamination had also reached the superheaters and the turbine.

As the corrosion risk was considered modest during continued operation, but high at the next shutdown if theunit was left unprotected due to the extent of the salt con-tamination, it was firstly necessary to prepare and thenimplement detailed dry preservation procedures for layup.The next unit shutdown due to a trip occurred shortly afterthe preservation plans had been prepared.

At this point, various further possibilities to remove thesalts from the superheaters, reheaters and steam turbinewere considered. As superheater and reheater tube sam-ples were taken during the shutdown which indicated thatthe salts remained on the top of the bore oxides, ratherthan being more deeply embedded within the layers, itwas decided that the most practical option for saltremoval would be a wet steam wash of the superheaters,reheaters and steam turbine. This could be achieved byincreasing the amount of spray water injected duringoperation with limited steam production. Furthermore,additional condensate polishing had to be established totake care of the contaminated condensate.

Over a period of several days, wet steam washes werecompleted of the superheaters, reheaters (via the super-heater bypass) and HP and IP (reheat steam) turbinestages. In practice, wet steam conditions in the reheatersand IP turbines could only be achieved under transientconditions for short periods. However, salts were clearlyreleased during the washes, with the concentrations alsotending to reduce with each repeated wash, providingsome confidence that the salts were successfully beingremoved. It was estimated that around 0.5 kg of salts wereremoved during the washing procedures, so this will havereduced the corrosion risk resulting from the contamina-tion.

Following the condenser leak, improvements to arrange-ments for on-line chemical monitoring instrumentationhave been made to reduce the response times for poten-tial contamination. This has included the installation ofspecific conductivity sensors in the condenser hotwell andadditional chemistry training for operating personnel.

The clean-up operation has previously been reported infull in PowerPlant Chemistry [6].

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REFERENCES

[1] Topp, H., Hater, W., de Bache, A., zum Kolk, C.,PowerPlant Chemistry 2012, 14(1), 38.

[2] Topp, H., Steinbrecht, D., Hater, W., de Bache, A.,PowerPlant Chemistry 2010, 12(7), 388.

[3] Stiller, K., Wittig, T., Urschey, M., PowerPlantChemistry 2011, 13(10), 602.

[4] Lendi, L., Wuhrmann, P., PowerPlant Chemistry2012, 14(9), 560.

[5] Cooling Water Options for the New Generation ofNuclear Power Stations in the UK, 2010.Environment Agency, United Kingdom, SC070015/SR3. Available from http://publications.environmentagency.gov.uk.

[6] Thomsen, K., PowerPlant Chemistry 2013, 15(3),216.

THE AUTHORS

Paul McCann (M.S., Chemistry, University of Nottingham,UK) is a specialist in power plant steam/water cycle chem-istry, corrosion and water treatment at the E.ONTechnologies Ltd. global unit in the UK. He has over 14years' experience in the power industry, joining Powergen,subsequently E.ON, in 1999. Paul McCann is also the cur-rent chair of the British and Irish Association for theProperties of Water and Steam.

Mark Robson (Ph.D., University of Leeds, UnitedKingdom) joined the Central Electricity Generating Board(CEGB) in the north east regional laboratories in 1980 andworked on a range of topics within the chemistrygroup investigating plant problems for 10 years. On leav-ing the CEGB he carried out various chemistry-based R&Dfunctions and acquired a Ph.D. from Leeds University inanalytical chemistry. In 2001 he rejoined the power indus-try working with various companies until joining RWEnpower in 2008. Since rejoining the power industry he hasbeen responsible for plant chemistry and environmentalissues, working as a station chemist and more recently asa chemistry and environment engineer in the corporateengineering function of RWE npower.

CONTACTS

Paul McCannE.ON Technologies (Ratcliffe) Ltd.Technology CentreRatcliffe on SoarNottingham NG11 0EEEngland

E-mail: [email protected]

Mark RobsonRWE npowerDrax Business ParkPO Box 3SelbyNorth Yorkshire YO8 8PQEngland

E-mail: [email protected]

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biapws 2014 power plant chemistry symposium highlights

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