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MINUTES OF 4th PIN MEETING, YORK UNIVERSITY, 30 NOVEMBER 2000 Welcome Colin Ramshaw, Chairman, opened the meeting by emphasising the two main areas of interest for the day: Rotation, perceived as unreliable by some, and bulk chemicals – in particular the need to acquire chemical kinetics to rationally design reactors.. Robin Perutz, Head of Department in Green Chemistry, York Univ., welcomed PIN members to York. Robin stressed the desirability to get a positive interest in chemistry at a young age. The chemistry side at York had good collaboration with industry, including involvement in degree courses. The BSc in Chemistry covered management in industry, and the MChem involved a year secondment to industry.. PIN Review David Reay reviewed activities in PIN over the last six months (overheads). Membership had now reached 260, with 50% from industry. Good progress was being made on the Guide to PI, and it will be launched at the BHRG PI Conference in Bruges in September 2001. It will also be announced at UK Heat Transfer 2001, where PI is a major theme. Discussions are also under way with NOVEM and Henk van den Berg about combining the proposed Dutch Guide with ours. Plans were in hand for the next PIN meeting, to be held at Heriot-Watt University, Edinburgh, in the Spring of 2001.. Richard Bahu has offered to liaise between PIN and a SOCSA visit to the USA, (led by Stan Higgins of Laporte) where some PI companies there will be contacted. Please send possible US contacts to DAReay@aol.com . David distributed a questionnaire (available to all PIN members on the web site) to solicit feedback on the features of most (and least) interest within the PIN ‘porfolio’.. Technical Presentations The first talk was by Malcolm Holmes of URENCO (mdh@cap.urenco.co.uk ). Malcolm described the centrifuge uranium enrichment process. Following on from Colin’s point in the Welcome, he said that URENCO’s existence depended upon the reliability of high speed rotating equipment. The uranium enrichment service, which uses gas centrifuges, is a mature business of over 25 years standing and an annual turnover of £300 million. Centrifuge improvements keep the plant competitive.. Many tens of thousands of centrifuges are used in cascade. The feed is uranium hexafluoride, with 0.7% U235 and this is concentrated by the bank of centrifuges to 3-5% U235. The UF6 is pumped to containers in cooling chambers. The original centrifuge was the Zippe type, later types are confidential. The gas centrifuge creates a very steep pressure ramp across the radius, gas entering at the axis and being removed at the periphery. Novel bearings (pin in a cup of oil) and magnetic bearings) are used, and the rotor is under vacuum.. The separation power is proportional to (peripheral speed)4 and length. R&D is driven by this need to attain higher speeds without proportional increases in manufacturing cost. The original aim was a design life of ten years and a 1% failure rate per annum. However, much older units are still running (second generation machines, URENCO now looking at the sixth generation). Essentially no maintenance is needed, the centrifuges outliving other parts of the plant. Speeds are >1000 rps.. Qualification is the key to reliability, and this takes 3-4 years, based on a pre-production run of several hundred units. Consistency of manufacture is important.. URENCO has looked at diversification – using the concept for other isotope enrichment; the production of composite products such as tubes and flywheels for energy storage. One application for the latter would be underground trains, with a 100 kg flywheel of 300 mm diameter x 1 m long storing 10 MJ. See: www.TheFlywheel.com . The keys to success, Malcolm said, were:
Some interesting points were raised in discussion. A chemical manufacturer said that he could not take 8 years to do the (development) work, and until rotating equipment of the quality of URENCO’s, he will not consider it. At this point Alfa Laval was asked when they would be marketing spinning disc reactors – they replied that design and prototyping was done, and the unit would be available in the near future. Tommy Noren of Alfa Laval said that his company had worked with centrifuges for many years (see Minutes of 3rd PIN Meeting, UMIST). He agreed that it was difficult for chemical companies to go into this technology. In response to another question, Malcolm said that as a separator to replace distillation, the centrifuges did not look attractive in cost terms. Reaction kinetics was the subject of the talk by Tony Haynes of Sheffield University, (a.haynes@sheffield.ac.uk ) (overheads). In particular the kinetics of the acetic acid process was examined. The basis was the BP Cativa process which is iridium-based. See www.shef.ac.uk/~ch1ah/ The route to acetic acid is via methanol and CO. The CO is inserted in the C-O bond of methanol, and needs a catalyst to give a good rate. (The reaction is important as world demand for acetic acid is 5.5 mt/a). The process is moving from the use of rhodium as a catalyst to iridium. The main components in the process are the reactor, flash tank (for catalyst recycle), a light ends column and dryer, leading to the product and propionic acid as a byproduct. One can remove one of the columns in the process by improving selectivity or getting rid of some of the water. Cativa can be retrofitted, and has promoters in the catalyst, which can more than double catalyst activity. There is high catalyst stability, higher solubility and faster rates at low water content. There is greater selectivity (better yield on CO).. Research has found how the promoters are working, correlations giving a good comparison with BP data.. In discussion, it was pointed out that with gas and liquid present in the reactor, can you be sure that the reaction rate was limited by kinetics only. Tony said yes, the experiments were done with high stirring rates, where mass transfer is not significant.. Mike Pilling of Leeds University (m.j.pilling@chem.leeds.ac.uk ) discussed gas phase processes. Laboratory studies of elementary processes form the basis, within the context of the Leeds Kinetic Data Centre. Here explicit chemical mechanisms are constructed, associated mainly with combustion and tropospheric chemistry. Combustion diagnostics & reduction of chemical mechanisms also feature.. With regard to elementary gas phase reactions, there is a good but insufficient data base of rate coefficients. Some fuels, and high temperature/high pressure data are not well covered. However, one can still construct explicit mechanisms for small species. Mike said that expert systems could help here. Once the mechanisms are constructed, they can be tested against experimental data. The results are made available via the WWW, requesting feedback.. An example is the Leeds methanoxidation mechanism. This considers VOCs affecting ozone. The oxidation behaviour of 123 VOCs has been described, in conjunction with AEA Technology and the Meterological Office. The data are being used by the DETR to develop an air quality strategy.. The mechanisms can be very large and demand excessive computer power. By mechanism reduction one can eliminate some species and reactions. The following site gives the methodology: http://www.chem.leeds.ac.uk/Combustion/Combustion.html#KINALC . Applications of mechanism reduction include combustion chemistry, HC cracking (propane pyrolysis) etc. 422 reactions & 48 species can be reduced to 50 reactions and 18 species. QSSA species are identified and the system can be described in 12 ordinary differential equations, rather than 48. As an example, one can plot the conversion and product distribution against distance along the reactor, for a typical steam cracker used by ICI.. Mike then went on to describe ‘lumping’ – where chemistry can be represented more simply by lumping species together in some way. Lumping could be used most easily with linear systems, whereas non linear lumping is complex. Mike said that timescale separation was a good way of looking at this. (See reference – Computers & Chemistry, 18, 45, 1993).. Coming onto home ground, Karen Wilson of the Green Chemistry Dept. at York (kw13@york.ac.uk ) reported on the kinetics of catalytic reactions, in particular designing new catalysts for liquid phase reactions. Karen said that the key to green chemistry was that it was better to prevent waste at source than to treat it afterwards. Catalytic methodologies were the preferred route to this. It was important, however, in heterogeneous reactions with recycling to ensure that the catalyst is working to its optimum performance. The rate limiting step can be diffusion in the pores, therefore one wants a large uniform pore structure, with ease of separation (filtration), high activity and high selectivity.. Karen described methods for preparing the catalysts – take mesoporous oxide & make it undergo post-modification and/or organic modification. She described the preparation of mesoporous silicas.. York has developed a range of catalysts based upon mesoporous structures for esterification, condensation reactions, as base catalysts and sulphonic acid catalysts. . One case study that was discussed concerned the production of linear alkylbenzene (LAB), from benzene and olefins which is conventionally catalysed by HF and AlCl3, which have problems with their associated waste. Using supported AlCl3/SiO2 there is an enhancement in selectivity towards LAB formation, and moving further using mesoporous silicates with 20-30Å pore size there is even greater enhancement.. All this, said Karen, had been enabled by progress in materials chemistry. Catalytic chemists can exploit mesoporous materials for new heterogeneous catalysts. In collaboration with engineers the applications can be tailored to batch reactors, plug flow, etc.. Colin Ramshaw said that this work highlighted the fact that heterogeneous catalysts can be stuck on surfaces and do not have the catalyst disengagement problems encountered with slurries.. Alison Wall and Lizzie Foord of EPSRC then gave comprehensive information on the chemistry and chemical engineering programmes and collaborations possible and being actively sought. Alison, Programme Manager for the Chemistry Programme, kicked off by giving the objectives and key issues. The chemistry support is directed at maintaining the health of the discipline and to identify key areas of industrial relevance, plus the training of postgraduate students.. A business plan is prepared every year, and the issues within it this year are based on the observation that there is a generally good alignment to the needs of industry, but industry is ahead in some areas. There is a concern about chemists being introverted, therefore interaction needs to be stimulated. There are perceptions that it is difficult for academia to recruit researchers, and industry is concerned about the quality of PhD’s.. Chemistry research grants are £47 million pa, of which more than 60% is spent on responsive mode proposals. There are specific calls, including chemists + chemical engineers.. Lizzie gave an introduction along similar lines to the General Engineering Programme. Strategic issues here are to ensure that the quality of the research base continues to improve, to bring in excitement & vigour and to tackle ‘bid’ problems via programmes such as IMI, Sustainable Technology etc., looking for step changes in engineering problems. Networks (e.g. PIN) and the support of good quality postgraduates also feature. Funding in chemical & process engineering is >50 million pa. 85% of the General Engineering Programme goes via responsive mode proposals.. Alison then gave examples of the type of support relevant to the PIN audience. There is no problem with joint funding of chemists & chemical engineers. EPSRC is very flexible with regard to length of project (1-5 years) and cost. £60 k projects for networks and mobility can be supported, and support to allow postdocs to ‘discipline hop’ is available. EPSRC can help towards the 4th year salary of a researcher who spends that year in industry. Collaborative grants involving industry are available. Feasibility studies for high risk and adventurous projects can be submitted at any time – particularly for a one year study. Next year co-operative grants bring groups together will become available. New ‘Centres of Excellence’ (funding to £1 million plus) can be considered if the area proposed is strategic.. More collaboration is needed in chemistry/chem. engineering. The current call closes 5 January 2001, and is the last in this series at present.. Then Lizzie Foord returned to introduce the forthcoming IMI call for outlines on 12 January 2001. Four page outline proposals are needed. They should be strongly industry-led, and incorporate a business process element. Typically a project would include three or more companies with 50-50 matching funds.. Lizzie introduced the Sustainable Technology Initiative. The deadline for outline proposals is 12 January 2001. Each project needs an element of economic, environmental and social sustainability in it. Key themes include improved resource-efficient processes & equipment. Excluded are power generation, renewables, end of pipe/clean up technologies etc. In Sustainable Technology, £15 million is available over 5 years. For IMI, £2.5 million per annum from EPSRC is being set aside, with further input from other programmes.. During discussion, Janet Etchells of HSE said that there was a need for interchange, in areas such as applying the large amount of reaction kinetics work being undertaken to, for example, spinning disc reactors. Safety is considered separate from the environment. Green chemistry has a lot of safety advantages. On the other hand, one could see environmentally-friendly processes which were LESS safe. One would not like to see this, and green chemistry and environmentally friendly processes need to be combined.. After lunch, Simon Waldron of the Hazard Evaluation Laboratory then discussed ‘the dirty end of chemistry’ (overheads). Lots of SMEs wanted to make high added value chemicals, with small tonnage outputs, necessitating multi-purpose equipment which was difficult to make tightly engineered for a specific process. Most of the reactions taking place are batch and exothermic.. If they are exothermic, one can study them calorimetrically. Some reactions have poor safety records (runaways). Studies are needed to answer: How can the risk be minimised? How can the process be operated efficiently?. Simon said that confident scale-up was easy for slow single phase reactions, but hardest for multiphase, high heat transfer, fast kinetics systems. When going from a small unit to full scale, temperature, time and the concentration-space history should be the same. Generally, companies cannot follow the design procedure in an optimal manner because they do not know all these parameters.. Simon believed that PI could make a contribution where kinetics are intrinsically fast. In choosing the calorimetry route, on can measure temperatures rapidly (easier than concentrations). Experiments taking 10 secs. can allow calculation of the activation energy, for example. One needs similarity between lab and large scale situation. An example of a decomposition reaction was given, showing differences in runaway rates in different vessels. One can convert the data to reaction rate vs. T and get a kinetic description of the process.. Impromptu Presentations. Dag Eimer of Norsk Hydro (dag.arne.eimer@hydro.com ) reported on a carbon dioxide capture project (overheads). In particular his interest was post combustion/precombustion sequestration, and conventional technology is too bulky and expensive. See http://www.co2captureproject.org/ Ideally costs should be $25/t CO2 net or less. A new radical technology, or new radical chemistry and less energy are needed. PIN, as a ‘group of unconventional radical thinkers’ may come up with the solution! Rob Klaassen of TNO (r.klaassen@mep.tno.nl ) described work on the integration of membranes in chemical reactors. In particular he has developed a membrane slurry reactor, for gas-liquid-solid reactions using a hollow fibre membrane. One feature is low hold up. A lab scale unit with a hydrogenation reaction has been tested, resulting in good conversion.. Good stability of filtration can be achieved. Applications include gas-liquid-solid reactions, small-scale fine chemicals and leading on to bulk applications. One avoids catalyst deactivation, reduces catalyst hold up, gets a broader size distribution and reduced attrition. John Hare of the Health & Safety Laboratory (john.hare@hsl.gov.uk ) talked on the lab’s activities associated with chemical reaction safety. These include venting, gas and liquid phase reactions etc. They possess reaction hazards calorimeters, where one can obtain concentration kinetics. This can be done at atmospheric or other pressures. There is a pilot scale reactor facility and a pilot plant for studying venting. The simulation of reaction heat electrically can be carried out. There is also a lab. scale reaction control facility. The lab carries out work for HSE and for industry, EU etc. They have employed students, and collaborate with universities for this, the students learning safe practices, etc. David Reay then outlined the recent Energy Efficiency Best Practice Programme call for proposals on low carbon technologies (see overheads in PIN Review presentation). A first assessment of proposals, following an announcement in October, was carried out in November, and two or three proposals relating directly to PI were considered. It is anticipated that the next assessment will be made in the Spring of 2001, and short (4 page) proposals will be considered in the interim period. In particular innovative 'out of the box' or 'off the wall' ideas are being looked for, with funding being offered in particular for feasibility studies, with typically DETR providing up to £20k per project, but this can be higher in exceptional cases. The main criterion for technologies is their potential to save significant amounts of energy/CO2. For further information, or comments on your ideas for a proposal, contact Cherry Tweed at ETSU (cherry.tweed@aeat.co.uk ) or Fiona Porter, who has responsibility for PI R&D, on Fiona.Porter@aeat.co.uk. Mick Hilton of Kvaerner Process Technology (mick.hilton@kvaerner.com ) discussed compact reforming technology, in the context of a collaboration with BP. The modern unit was more compact than traditional reformer technology, unchanged for 25 years, and Kvaerner had 250 of the new units installed world-wide. The capital cost of these units was 60% of that of the older design.. The tubes are put into the flames of the burner (rather than downstream). Thus there is an integral heat exchanger and a countercurrent unit. The pilot plant is at Warrensville (BP). CFD models revealed good flame propagation, and the resulting plant has 30% of the original plot area, 50% of the weight, 60% height saving, and has 90% efficiency (compared to 60% for the old design). The 20 t/h capacity makes it compatible with a ‘world unit’.. An update on the activities of the Dutch PI Group was given by Willem de Vries of NOVEM (w.de.vries@novem.nl ). He described the Spirit programme, looking at the breakthrough of new technologies leading to PI. The recent conference on the topic had 90 participants, mainly from chemical & food sectors. The ‘hot’ items were a ‘twister’ for gas treatment, removing moisture, and a starch process which gave 60% energy savings and 80% of the trouble of the process being replaced!. A questionnaire handed out there showed that more than 80% said they needed PI, 60% thought it a nice academic toy, and more than 80% felt that additional education was needed, (overheads). Willem said that they found that the biggest driver was cost reduction. Many opportunities were felt to exist in the paper & dairy sectors. A key to success was GOOD SUPPORT FROM MANAGEMENT.. Henk van den Berg (h.vandenberg@ct.utwente.nl ) followed Willem by stating that a systematic analysis of opportunities for PI ion their processes is not easy for many companies, and they should be invited to sit down with a consultant who can take them through the opportunities. (overheads). Representing ECN in the Netherlands, Luci Correia (correia@ecn.nl ) described activities there on heat exchanger reactors. A bench scale unit should be tested during January 2001, currently they are studying channel flows etc. with CFD. It is felt that the small channel unit will have up to 70% selectivity, compared to 40% with larger channels and 20% for a batch reactor.. Working Groups. Two parallel working groups were run, one on reactors (Colin Ramshaw) and the other on separations (Dag Eimer). The results were summarised in a common session:.
THE NEXT PIN MEETING WILL BE AT HERIOT-WATT UNIVERSITY, EDINBURGH, ON TUESDAY 15 MAY 2001 |