Following the successful 'CryoPrague 2008' conference and the gasworld review of this event, Professor Ralph Scurlock provides a cryogenics industry professional's view of the conference.

Prague as a conference centre
The Czech series of biennial IIR conferences on cryogenic technology include Commission A1 ( Cryophysics and Cryoengineering ), A2 ( Liquefaction and Separation of Gases ) and A3 ( Cryobiology and Cryomedicine ). Cryogenics 2008 was the tenth conference in the series organised by the Czech National Committee, and was held in the south of Prague at the Pankrac Conference Centre, some five stops on the Metro from Wenceslas Square.

Prague is becoming a centre for international conferences and two years ago the Cryogenics 2006 IIR conference was subsumed by the ICEC and ICMC conferences to create a mega-conference of 600-plus participants called ‘CryoPrague 2006.’ In three years time (2011) some 2000-plus participants of the giant ‘IIR Congress on Refrigeration and Cryogenics’ will meet at the Prague Congress Centre.

It was therefore very pleasant this year to take part in the smaller Cryogenics 2008 conference, organised by Vaclav Chrz, Stanislav Safrata, Pavel Schustr and their local organising committee. The number of delegates attending was about 150, representing 23 countries. A total of 55 papers were presented, including 40 oral and 15 poster papers, while the accompanying exhibition included nine exhibition booths.

The full texts were available at registration as a book of proceedings with accompanying CD’s, while the full list of papers can be found on the conference website www.icaris.info/Cryogenics2008

Centenary of the International Institute of Refrigeration
2008 is the centenary of the creation of the IIR, in 1908. Didier Coulomb, Director of the IIR, described how on 5th October 1908, some 3000 specialists in the rapidly expanding field of ‘artificial cold’ gathered in the Sorbonne, Paris for the formal opening of the First International Congress of Refrigeration. The Congress culminated in the founding of the International Association of Refrigeration, which was renamed the International Institute of Refrigeration in 1920.

Now in 2008, while the IIR has changed, its principles are still alive: the role of refrigeration in agriculture and food, the importance of science and technology in refrigeration and especially cryogenics, and the need for scientists to share their research.

Coulomb described the committee structure and how its Science and Technology Council comprises ten Commissions. The IIR also has its own publications and newsletter, while a major activity exists in the holding of conferences and congresses. The most important challenges in the 21st century are in health and the environment, where the importance of refrigeration will be carried forward by the IIR.

Centenary of liquefaction of helium: A tribute to Professor Kamerlingh Onnes
2008 is also the centenary of the first liquefaction of helium, and so the
Cryogenics 2008 conference began with Prof. Ralph Scurlock’s tribute to Professor Kamerlingh Onnes of the Cryogenic Laboratory, University of Leiden in The Netherlands. His successful liquefaction of helium back in 1908 was achieved when gases and material resources were almost non-existent, and when the necessary infrastructure had to be built up ‘in-house.’

Kamerlingh Onnes was probably the first scientist to adopt a ‘big science’ approach in building up his new cryogenic laboratory from the year 1882, and together with his colleague and mentor, Professor Van der Waals of the University of Amsterdam, he was able to estimate correctly the critical parameters of helium. This enabled him to design, build and operate the coldest portion of his liquefaction cascade with a JT expander and refrigerator, which produced liquid helium for the first time on 10th July 1908.

The tribute included a brief outline of how Kamerlingh Onnes opened the door to the physics of macroscopic quantum phenomena. His success led to the extraordinary range of cryogenic applications we know today, culminating in the 2008 inauguration of the enormous cryogenic system of the LHC particle accelerator at CERN, Geneva, with its 27km of superconducting magnets operating in superfluid helium at 1.8 K

Fifty years of liquid helium in Czechoslovakia
As a reflection on this historical introduction, we were introduced by Z. Kaiser of Ingersol Rand in Prague, to the first helium liquefactions in Czechoslovakia nearly 50 years ago. After the founding of the Department of Low Temperatures of the Institute of Nuclear physics of the Czechoslovak Academy of Sciences in 1956, the first helium liquefier was commissioned with the support of Piotr Kapitza in Moscow, manufactured in the KSB works in Decin (now Chart Ferox as.) and installed in the Low Temperature Department in Rez, just outside Prague.

The liquefier was a sub-cooled nitrogen and hydrogen cascade, producing eight litres of LHe per hour and produced liquid helium for the first time in April 1960.

In 1964, the manufacture of the second generation ZH liquefiers (producing four and nine litres per hour) was started at Decin, with the support of Kapitza, using a piston expander instead of hydrogen sub-cooling.

Import restrictions from the US across the Iron Curtain, prevented the purchase of the successful Collins helium liquefiers, and so the Czechoslovak ZH liquefiers became widely used, particularly in universities and research institutes in Central and East European countries. With industrial demands for liquid helium increasing, rotating machines, including screw compressors and radial turbine expanders were the answer.

From the mid 1980’s, the development of miniature high speed turbine expanders commenced at Ateko in Hradec Kralove in cooperation with the State enterprise PBS in Velka Bites. The first liquefiers were built by Ferox in Decin (employing firstly turbine expanders, and later screw compressors).

However, following the Velvet Revolution in December 1989, the liquefier markets collapsed and the manufacture by Ferox of helium cryostats and liquefiers was abandoned after making a total of 45 liquefiers.

Subsequently, Ferox was taken over by Air Products and manufacture was concentrated fully on equipment for liquefied air gases systems, and later LNG. Meanwhile, the manufacture of turbine expanders was continued by both Ateko and PBS. For example, 258 turbines were delivered to Linde AG for its LKKA liquefier during the period 1988-1992. The quality of these turbines has established these
two firms with a wide market and is a reflection of the high value of Czech technology. With growing confidence, much larger turbines are now being made for the large 1-2 KW helium liquefiers now required, particularly for the CERN LHC
cryogenic systems.

Furthermore, expertise in making precision high speed rotating machines has led to another significant success, with PBS producing the large cold compressors needed by CERN and others in pumping the liquid helium used for cooling superconducting magnets down to 1.8K at a pressure of 0.002 bar.

Green Cryogenics: a recurrent theme throughout the conference
As cryogenics is so energy intensive, the seemingly never-ending rise in oil prices, and the associated step function in the rise of energy prices over the past year, caused considerable and serious concern throughout the conference. The introduction of the term ‘green cryogenics’ and the associated need to improve Carnot efficiency in the production and use of cold, provided a recurrent theme, with many papers describing efficiency and testing improvements which their respective authors were achieving.

The following examples, of the wide range of papers given at the conference, illustrate how cryogenic efficiency is now dominating the technology in industry and the laboratory.

Low loss management of cryogenic liquids under pressurised storage
A timely paper by T. Hnizdil, J. Suma, M. Kouba and V. Chrz, Chart Ferox a.s, described experiments on the performance of high pressure, vacuum insulated tanks in relation to stratification of both liquid and vapour, under various management procedures. The heat of vaporisation of nitrogen is very small at pressures around 30 bar, which causes high evaporation rate and short holding time.

For minimum loss, it was recommended that special tanks with multi layer insulation can provide twice as long holding times. Further, the remaining liquid before re-filling should be minimised and maximum filling should be optimised with respect to stand-by periods. PBU circuits should also be shut-off during stand-by periods.


Stand-alone LNG supplies via low loss, vacuum insulated, containerised tanks
In a paper by P. Matl, M. Lansky and V. Chrz, Chart Ferox a.s, the enabling of stand-alone LNG supplies or regular ‘virtual pipeline’ deliveries was described via the development of 40 foot LNG ISO containers, each holding currently the largest volume in the world of 43.5m3.

Progress of LNG technology for fuelling ferries also required the significant development of wide bore, 150mm, vacuum insulated pipelines in sections linked by demountable couplings, as was described in a paper by D. Takacs and V. Chrz, Chart Ferox a.s.

Structured packing in floating ASU’s
In a paper by M.A. Kalbassi, B.Waldie, V. White and C. Bell, Air Products plc, was described the experimental modelling of liquid distributions across a 1m diameter, structured packing column and the effect of tilt angle and motion on floating air separation units. It was found that a tilt angle of 4 degrees caused significant mal-distribution, while tilts of 1 degree would still have to be taken into account in the column design with the structured packing employed. The solution was found in designing a special type of packing, which splits the volume of the column into parallel micro-columns, which keep regular distribution of liquid across the column area.

Doubling the output of helium cryocooler/condensers
In one paper on cryocoolers by C. Wang and R. Scurlock of Cryomech, it was shown that by stealing some cold from both regenerator and expander tubes for precooling purposes, the liquid helium output of a pulse-tube cryocooler/condenser can be doubled.

Efficient liquid helium management at the South Pole
Another paper which illustrated the drive towards greater efficiency was that by
R. Baker and P. Sullivan of Raytheon Polar Services, entitled ‘Efficient management of liquid helium at the South Pole Station during the Austral winter’.

The South Pole environment is the highest (at 3000 metres), the driest, the coldest (at -50°C, below the freezing point of rubber O-ring vacuum and gas-tight seals), and the windiest place on the planet - very hostile particularly to cryogenic systems. The Austral summer provides a 3 month slot for safely flying in and out, and liquid helium storage needs to last a whole year, otherwise many astronomers have to stop work.

A purpose built 3000 ft2 cryogenic laboratory, assembled in 2006 and heated by the compressors of the cryocoolers used for re-condensing the boil-off, has increased the handling efficiency enormously. Liquid helium is available for many more applications now with the major part of the boil-off gas being re-condensed.

Moreover, development work is demonstrating how pulse tube cryocoolers, with no moving parts in the cold head, can be employed outside in the harsh Antarctic environment to cool directly the detectors on the telescopes.

Cryobiology
A review paper by P. Mericka of the University Hospital of Hradec Kralove, described the widespread expansion of the applications of tissue preservation into many areas of hospital practice; and how the tissue bank at Hradec Kralove, established in 1952, had pioneered many of these applications.

He explained how initially, until the 1990’s, there was no regulation of tissue and cell bank activities, neither by voluntary standards nor by State health care authorities. However, the EEC has now become involved culminating in the issue of the 2006 EC Directives. For example, freezing and storage must now be via contact with gaseous rather than liquid nitrogen, to eliminate cross-contamination between different tissue/cell samples. This step makes the control of freezing protocols much more difficult.

In another paper, G. Sporl, Institute of Air conditioning and Refrigeration in Dresden, analysed freezing protocols and described a capsule technique, called a ‘hedgehog’, for controlling and homogenising freezing rates across the whole of tissue samples. This device supports the extended use of tissue banks today.

Mericka described how originally, tissue banks were for storing tissue some time prior to their clinical use. Today, tissue banks have started to introduce methods for ‘modifying the properties of the original tissue with the aim of lowering immunogenicity (ie. lowering the capability of cells to produce an immune
response), and to enhance or prevent tissue rebuilding in the organism of the host’.

Coping with and instituting safety procedures and accurate freezing protocols is therefore much more important today.

Technical Visits
The conference concluded with a day of technical visits, preceded by an introduction to whole body cryotherapy, a stimulating experience which is claimed to be ‘good’ for you in many ways. This technique was invented in Japan and has spread to Europe, particularly Poland where some 60 cryotherapy centres have been established.

A visit to the Prague Centre demonstrated how exposure to evaporated air at -120°C for 30-60 seconds was the basis of the cryotherapy. Younger participants had a trial session, but not the older members of the party who felt that perhaps sea-bathing was possibly just as stimulating.

Other technical visits included the two air separation plants at Litvinov, the recycling of Freons at Praktik Liberec, and the large superconducting magnet separator for cleaning kaolin ore at Lasselberger Kaznejov.

Conclusion
In conclusion, the Cryogenics 2008 conference covered a wide range of cryogenics over the four day meeting, showing once more that the biennial IIR series is an important international focus in the centre of Europe for the technology.