The high temperature workshop at Woburn

Citation

Cox, W.M. (2002), "The high temperature workshop at Woburn", Anti-Corrosion Methods and Materials, Vol. 49 No. 5. https://doi.org/10.1108/acmm.2002.12849eaa.001

The high temperature workshop at Woburn

The high temperature workshop at Woburn

Just occasionally, normally by accident, I find myself in a meeting that I would never have expected to attend, but which turns out to be massively interesting or exciting. Although the sleepy village of Woburn might well be described as interesting, my guess would be that the last time anything exciting happened there was around about the time of the reform of the monasteries. It was a Dutch colleague who first mentioned that he was thinking of attending, and attendance was by invitation only and capped at 50 delegates, but luckily I could be invited. The main reason why I eventually signed up was that an American co-worker had offered a paper on some work in which I was involved. In any case, the attendance fee was reasonable and included accommodation at the "Inn at Woburn". It was June in the Bedfordshire countryside, and the weather was that particular blend of clear skies, intermittent showers, light wind and sunshine that make the fields seem especially green and soporific. I drove down from Manchester on Sunday evening, forgetting that it was the end of the spring half-term school break, and what should have been a two-hour journey took all of twice as long.

The key protagonists who had organised the event, the 3rd International Workshop on "Life Cycle Issues in Advanced Energy Systems", were Jim Norton, formerly based at the Petten laboratories in The Netherlands, Wate Bakker, still essentially Dutch, despite years of exposure to the USA at EPRI, Ian Wright, still essentially North of England, despite years at Battelle, then EPRI, and now Oak Ridge, and Shigemitsu Kihara, now the general manager of the Research Laboratory at Ishikawajima-Harima Heavy Industries.

I would have been happy to go to Woburn, or just about anywhere else for that matter, to meet any of these individuals, so to find them together, and virtually on my doorstep, was a superb bonus. However, that was just the start. John Oakey, now getting things nicely together at the University of Cranfield, opened the proceedings and Ian Wright chaired the first session, which was on "Advanced energy systems". It is not feasible to cover in detail all the excellent presentations made over the course of the meeting, but I will highlight just a few to give you a flavour of the workshop proceedings.

The first presentation was given by Neville Holt of EPRI, who has been closer to the various gasification programmes than anyone else in the world. Birendra Nath from Innogy (formerly National Power) summarised experience on coating degradation and refurbishment on power generation gas turbines. Larry Ruth, who is reportedly one of the main movers behind the US DoE's "Vision 21" initiative, followed up with an incisive and pragmatic overview of the energy picture in the USA. For those of us who might have concluded that the age of fossil energy was passed, Dr Ruth pointed out that the USA has the largest coal reserves of any country in the world and, furthermore, USA coal reserves are equivalent to the entire rest-of-the-world reserves of oil. This is not a resource that is going to be ignored. The goals of the Vision 21 initiative are to remove all the environmental issues by means of the application of new technology for coal. This translates to a target of 60 per cent thermal efficiency, CO₂ sequestration, and the development and introduction of innovative new technologies for coal utilisation. Envisaged new technology developments would almost certainly include gasification in one form or another, the use of fuel cells, and the much-trialled hydrogen fuel economy.

No sooner had we assimilated this information than the first speaker from Japan, Kensuke Yamamoto from IHI, informed the workshop about progress in the ultra-super-critical (USC) steam condition plants and PFBC combined cycle systems currently under development in Japan. In particular, the application of new ferritic stainless steels in superheater headers is allowing unit efficiencies to be increased, yet the thickness of superheater headers and other high pressure components to be reduced, thereby cutting the capital cost of such units by approximately 10 per cent.

The information deluge continued: Richard Fordham (Petten) on increased reliability and efficiency in Waste-to-Energy systems, Fred Starr (formerly British Gas, now with European Technology Development) on the impact of load-following and two-shifting operation on advanced energy system plants. John Wheeldon (EPRI) gave a particularly amusing but nonetheless in-depth review of hot gas filtration and then the frighteningly fragile but dauntingly obvious bare-tube slag-coated heat exchanger development at EERC, North Dakota, was described by John Hurley. We had only got as far as lunch-time on the first day. Could this pace really continue?

Yes it could. Jim Norton chaired the afternoon session – back on his home territory of oxidation. Juan Carlos Nava summarised the thinking at ABB (now Alstom) in Spain, Hans Pastoors updated everyone on the excellent current operational experience at the Buggenum gasification project in The Netherlands, and then the excellent Kiyokazu Nakagawa (IHI) surprised and delighted everyone by proving without doubt that steam conditions on the inside of a pipe could affect oxidation performance on the outside. Clearly, this was a ridiculous idea – until presented with the detailed results of a comprehensive investigation programme on the new ferritic alloys, and there was no doubt at all that the IHI findings were completely correct.

Next, the delegates had an update on the Elcogas IGCC power plant in Spain from Ana Maria Lancha (CIEMAT), and Tan Levi rounded off the day with a review of power plant life cycle issues from Australia and New Zealand, gave a new perspective on it (geothermal power) and highlighted the absolute contrast between conditions in two countries that invariably are lumped together for no reason other than the fact that they appear to be relatively close when looked at from Western Europe.

Richard Fordham chaired the first session of the second day, continuing the Mixed Oxidation Gaseous Corrosion theme. John Nichols (University of Cranfield) provided an update on the LEAFA project, modelling oxide spallation behaviour, pointing out that the rate of corrosion in combustion gas is always quicker than in air. The young Japanese researcher, Mitsutoshi Ueda (in another high quality presentation from IHI) presented the detail of oxidation behaviour on steam side oxidation of the new ferritic alloys in USC service environments. Yet another "heavy hitter", Joe Quadakkers, from Forschungszentrum Julich in Germany, presented the most recent ideas on fuel cell materials for advanced energy systems, explaining in detail the development of the metallic (chromium-based) alloys for interconnect materials (see Plate 1). His presentation was followed by some interesting observations from David Young (School of Materials Science & Engineering, New South Wales) relating to high temperature carbon corrosion in solid oxide fuel cells and, in the final paper of this session, Nigel Simms, John Oakey's trusted cohort from the Coal Research Establishment, who is now also at Cranfield, reviewed the objectives, mechanics and progress towards the Materials Degradation Database that forms the basis of the "COST 522" European Collaborative Project.

Plate 1 Joe Quadakkers (Forschungszentrum Julich) gives his presentation in the session chaired by Richard Fordham (Petten)

The third session was entitled "Deposit-induced corrosion" and it was chaired/presented/orchestrated by Wate Bakker. Michael Spiegel (Max-Planck Institute, Düsseldorf) led off with an update and clarification on fundamental aspects of chloride-induced corrosion in power plants – a subject of hot international debate because of the NO_x reduction initiatives presently under way in Europe and North America. On the one hand, for many years the received wisdom was that high chloride coals did not cause higher rates of corrosion/degradation to radiant section tube walls. Then, with the introduction of staged combustion and more or less effective designs of "low NO_x" pulverised coal burners, online corrosion suddenly was recognised to be a significant contributor to attack, but the reasons why this occurred were not fully understood.

Wate himself gave the next presentation on the subject, effectively summarising the results of numerous EPRI projects, together with accumulated knowledge, personal opinion and the latest developments in the corrosion theory. It appeared that the so-called "pyrite theory" of high temperature attack in reducing conditions had receded somewhat, but the contribution of chloride in reducing conditions is gaining in certainty, especially in North America.

Martin de Jong (KEMA) reported recent results from the simple but elegant "KemCop" corrosion probe investigations in Europe and North America, and Kevin Davis (REI, Salt Lake City) reviewed recent online high temperature electrochemical corrosion monitoring in laboratory trials and field experience that has been conducted in a context of advanced CFD modelling of power generation and waste-to-energy boilers. A particularly interesting aspect of this work was the precision metrology approach that has been developed in conjunction with the University of Utah to verify the capability of modern instrumentation to provide quantitative tube wastage rates. Davis also clarified that high temperature chloride attack was not a problem as long as the boiler operated in oxidising conditions, nor was there much in the way of hard experimental evidence to support the idea that high temperature attack was a function of pyrite content, though chloride corrosion under oxidising conditions in the absence of sulphur needs more investigation. However, as soon as low alloy steel furnace wall tubes operated at high heat flux under reducing conditions, or under alternating oxidising and reducing conditions, then even comparatively minor chloride content in the fuel had a very marked impact on high tube wall corrosion, the wastage rate being primarily a function of the heat transfer rate. He concluded, however, that there did not appear to be any overriding reason why the problems could not be avoided with appropriate control of combustion environments.

Throughout the proceedings thus far delegates had become aware of the tendency of a rather noisy German engineer to voice comments that were evidently not fully in sympathy with the assembled wisdom of the high temperature cognoscenti. This individual turned out to be Joerg Krueger, from the MSB Waste-to-Energy plant in Schwandorf, and his presentation came next. However, it gradually became evident that Herr Krueger was not talking out of his hat. He was, in fact, speaking with the direct authority that comes only with direct hands-on plant experience and responsibility. I believe, that over the course of the meeting, all delegates came to recognise the quality and importance of Joerg Krueger's contributions. It was true that he was not in tune with the academic in-crowd, but he brought a depth of perspective and insight that added significantly to the relevance of discussion and evaluation in the Workshop.

Jeff Blough (Foster Wheeler/McDermotts, USA) rounded off this session with an overview of materials-testing results in waste-to-energy plants in the USA. Jeff has been working on this for many years and has conducted a series of plant materials trials on behalf of EPRI and DoE in power plants and waste-to-energy boilers. In one aspect of his talk he also highlighted an interesting cracking feature that was attributed to corrosion fatigue that, it was concluded, was "definitely not a fabrication error" (but which, nevertheless, was remedied by means of a post-fabrication annealing procedure).

In the final session of day 2, John Nichols returned to the podium to report recent results on the NSF/EU joint programme to investigate the erosion characteristics of electron beam physical vapour deposition thermal barrier coatings (EB PVD TBCs) and, lastly, Ian Wright (ORNL) reviewed accumulated experience from the recent history in bubbling PFBCs. I am sure that I was not the only person who felt that this talk would be a makeweight. I was wrong – what followed was the most comprehensive assembly of accumulated practical and research experience that I have ever heard. I mentioned it afterwards to John Oakey, who said that Ian had indicated that there was a story to tell and important information that should be recorded. We had to agree on both counts.

The meeting adjourned and Workshop delegates were taken for a tour of Woburn Abbey, followed by dinner in the Sculpture Gallery accompanied by live music played on a harp. I am not a big devotee of conference dinners, but this was special, and was a fine opportunity for the non-UK delegates to experience good British food in what could only be described as an exquisite environment (see Plate 2).

You would have thought that delegates would have been reaching information overload by the start of day 3, but you would have been mistaken. The session on "Future perspectives" was chaired by John Nichols. The European perspective was provided by Mike Henderson, formerly of DERA and now heading up R&D at Alstom. The sub-heading to his talk was "All change in the energy market", and Mike went on in the next half hour or so to give a comprehensive route-map of how this might translate in a European context.

Plate 2 Workshop delegates and their partners enjoy the atmosphere before dinner in the Sculpture Gallery at Woburn Abbey

The second presentation, representing the situation from the Japanese perspective, was given by Shigemitsu Kihara (IHI). In a strikingly thoughtful and perceptive talk, Dr Kihara contrasted the prevailing government view of continued growth and increased energy consumption with a new emphasis on improved energy utilisation efficiency, reduced pollution, and enhanced materials development. Details of active and scheduled R&D initiatives were intermingled with reports on current developments and targets for probable future goals in the areas of power plant technologies – USC plants, IGCC systems, advanced waste firing (" … the amount of waste is not increasing, but there is keen interest in reduction of toxic emissions … " and " … we do not need more plant. We need more efficient plant … "), and fuel cells.

The last presentation was by John Stringer (EPRI), and was little short of a tour de force on the US perspective, incorporating both DoE and EPRI considerations for future direction. Stringer first clarified that the EPRI interest differed in that it was concerned primarily with electricity production, whereas the attention of the DoE related to the strategic national view of energy sourcing and utilisation. What followed was what will, in all probability, be a blueprint for clean coal, clear skies, climate change management and homeland security for the next 20 to 30 years.

Stringer first acknowledged the input from Larry Ruth (DoE) and then went on to review issues such as the "3P" pollution reduction targets (NO_x, SO₂ and Mercury) by 2008/2010, while recognising that coal will remain competitive and will retain a large portion of the energy market. Nevertheless, innovation will be needed to meet the new energy and environmental challenges. Coal and gas generation will tend to increase, nuclear will remain steady, as will renewables. There will be new capacity additions – there will probably be a requirement for an additional 31GW of new generating capacity by 2020. Issues such as the reduction of carbon intensity, improvements in efficiency, sequestration of carbon dioxide, population reduction and the possible impact of reduced GDP were all mentioned and will be taken into consideration.

Other issues were again the impact of fuel cell systems, the Vision 21 initiative, targets for coal efficiency, the overriding importance of plant reliability, increased use of solid wastes, and the probable increased take-up of prognostic maintenance tools.

The depth of information provided by these last three strategic perspective presentations alone would have justified the Workshop attendance fee. After a quick break for coffee, the meeting reconvened for a panel discussion chaired by John Oakey, in which Len Pinder (PowerTech) took over from Mike Henderson (see Plate 3), and which included some excellent presentations from the floor, notably by Ken Natesan (Argonne National Laboratory), Jerry Sorrell (NiDe), Peggy Hou (Lawrence Berkeley National Laboratory) and Stuart Saunders (NPL), who also made a valiant attempt to act as Rapporteur for the discussion. The whole meeting ran precisely on time, there were no no-shows, no poor presentation, no one left early, and the venue and organisation were first-class.

Plate 3 Panel members (from left to right) John Stringer (EPRI), Shigemitsu Kihara (IHI) and Len Pinder (PowerTech) with discussion chairman John Oakey (Cranfield)

The meeting was sponsored by EPRI, Oak Ridge National Laboratory, the European Commission and Cranfield University. Regrettably, the proceedings will not be published by ACMM. However, they will be published (with an accompanying CD-ROM) via Materials at High Temperatures (www.mht.org.uk) and you can order your copy by contacting John Nichols, the UK and European Editor, on j.r.nichols@cranfield.ac.uk It is some years since the last Workshop, and no one seemed very certain when the next one might take place but, if you are involved in this field, do not miss the proceedings, and make sure of your invitation for the next meeting – this one was a peach!

William M. CoxTechnical Advisory Editor and Chairman of the Editorial Board, ACMM