- Email: [email protected]
Experience of Product Engineering in a Group Design Project
0263–8762/04/$30.00+0.00 # 2004 Institution of Chemical Engineers Trans IChemE, Part A, November 2004 Chemical Engineering Research and Design, 82(A11): 1467–1473
EXPERIENCE OF PRODUCT ENGINEERING IN A GROUP DESIGN PROJECT A. SHAW1, H. N. YOW1, M. J. PITT1, A. D. SALMAN1 and I. HAYATI2 1
Department of Chemical and Process Engineering, University of Sheffield, Sheffield, UK 2 Borax Europe Ltd, Guildford, UK
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student project is described which involves both product and process design in the field of particle technology. This is predominantly a student view of both the technical and educational aspects of the dehydration of boric acid, in which the product specifications as well as the process were initially unknown. Although the final product proved insufficiently stable to moisture for commercial application, the exercise was judged a success by the students, academics and industrial sponsors. Keywords: product engineering; education; particle; dehydration; boric acid.
INTRODUCTION Particle technology and product engineering have been stated to be key areas in both chemical engineering research and education (e.g. Favre et al., 2002; Williams, 2003), and are strongly linked. Taught courses in particle technology are well established, but the topic has been rare in projects (Chase and Jacob, 1998). Following an IChemE Product Process Interface Working Party report and a meeting of the IChemE Education Subject Group in 1999, UK departments have been working to introduce product engineering into their taught courses (Seville, 2000), and a textbook has been produced (Cussler and Moggridge, 2001). The design project is a sine qua non in third year chemical engineering and provides an important stepping-stone in student development. The emphasis shifts away from conventional teaching, which requires a modicum of student impetus, and moves toward a situation where students think independently of their supervisor to overcome problems, yet still have the tutor as a guiding safety net. The projects typically involve the design of a process to produce a chemical product but their directions can be very diverse, and different universities manage them in different ways. The arrangement at the University of Sheffield is for each group (up to five students) to work on a different project supervised by one or two academics. The project has to meet the requirements of IChemE accreditation, but this does not mean that it is limited to the design of traditional plants. As part of a drive to develop interesting and challenging topics for the MEng students, Borax Correspondence to: Dr A. D. Salman, Particle Products Group, Department of Chemical and Process Engineering, The University of Sheffield, Mappin Street, Sheffield, SI 3JD, UK. E-mail: [email protected]
Europe contributes a project for one group each year. A project involving particle technology has been reported previously (Patel et al., 2003), but this is the first report of one which can be properly described as product engineering, that is, one in which the students were concerned with the functionality of the product. It should be noted that a research project is carried out in fourth year, but in recent years some element of research has been possible in the third year design project, similar to that described by Seville (2000). It is usually academics who claim that a project benefits students, but this paper is predominantly a student’s eye view. WHAT SETS THIS PROJECT APART FROM ‘CONVENTIONAL DESIGN PROJECTS’? At the project conception, when the objective was put to the students, both the supervisor and the Borax representative had no concrete idea of what shape the project would take. The project involved a pioneering process to create a chemical product in which the viability of the design was to be thoroughly investigated by the students. The originality defined the whole scope of the project as it placed more emphasis on students to discover the best design, since there were no preconceived ideas to follow. This separated the project from the more classic examples, where the design being investigated utilized existing technology and working plant designs that had already been implemented. Owing to the novel nature of the work being carried out, neither Borax Europe Ltd nor the supervisor could answer all the questions posed and it was therefore down to the students to find their own answers. This meant they had to think analytically about their questions and propose theories for discussion and investigation. The discussions
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were fuelled either through literature findings or, more significantly, through experimental research on observations of phenomena critical to the design. The research facet of the project provided the most significant highlights, as most conventional projects did not offer this opportunity, because their processing conditions and materials were too hazardous for students to create and use in the laboratory. The broad spectrum of experimental work required provided the students with a great opportunity to familiarize themselves with a wide range of equipment as well as becoming proficient at organizing the planning and running of experimental activities. The findings from the research directly affected the design and made the project a more stimulating experience; gathering material property data that affected design by experiments, rather than simply collecting information from literature with no real comprehension for the physical meaning, was an enriching experience. The fact that even published data contradicted the research observations of the students augmented the dynamic and exciting nature of this project. The project objective was only given as a guide and it was down to the students to meet or surpass the outline. Since the decision was taken to obtain a purer product than initially suggested by Borax Europe Ltd, costing was left to the students’ discretion. This gave the students the ability to control the economic stability of the project, not only by process design but also by product cost, a situation not usually experienced by students taking design projects. An industrial link project is always mutually beneficial to both parties as the students enjoy an opportunity to work on a real problem, which has greater scope for exploration and development, and the company benefits from the preliminary design and research. The research findings of this project were significant as they indicated an unstable product, due to its strongly hygroscopic nature, which has led Borax Europe Ltd to cease investigations into its commercial production. Thus, Borax have benefited substantially from this work as they have received conclusive evidence that the process is not viable. Borax Europe Ltd have therefore saved time and money on their investigations by collaborating on this project and, because of the conclusive outcome, can now begin looking to expand their product portfolio elsewhere. Overall, the points raised here show that, with an industrial link, the design project can be taken out of the old mould, following typical design procedures and existing processes, and formed into a truly exciting prospect for the students without the need for huge departmental spending, which often limits the availability of quality projects.
BACKGROUND—THE PROJECT Now, let us peep into the scientific world behind the project. Boron oxide is widely used in glass making because it can withstand high temperatures and thermal expansion. This makes it a key component in the manufacture of borosilicate glass. Boron oxide also has applications as a deoxidizer and flux in metallurgy and in the bearings of turbines in the form of metallic borides, where hardness and resistance to corrosion are required. It is also used in the nuclear industry as a moderator for neutrons. Boron oxide is conventionally produced using fusion of boric acid at 500– 10008C; however, this involves the production of a vitreous melt, which is corrosive to refractory linings and steel. The corrosive nature means that reactors must continuously be renewed at regular intervals and also causes contamination of boron oxide by corrosion products. The potential for a higher purity product therefore exists by using alternative routes of processing. Since it is the most commercially valuable oxide of boron, Borax felt it would be advantageous to develop its product range to incorporate boron oxide as part of its portfolio. The proposal was to use boric acid already produced by Borax Europe Ltd to procure the new product by fluidized dehydration. There were proposed mechanisms for the dehydration reactions of boric acid already in existence complemented by temperatures at which these reactions occur, although enthalpies associated with the reactions were still subject to debate between researchers. Table 1 shows formulas and important temperatures, also giving the dehydration reactions taking place. Boric acid, H3BO3, can be regarded as hydrates of boron oxide. They are formulated as B2O3.3H2O or B(OH)3 for Orthoboric acid and B2O3.H2O or HBO2 for Metaboric acid. Orthoboric acid has a normal melting point of 1718C; however, when heated slowly, it loses water to form metaboric acid, which contains less residual water and may exist in three crystal modifications as specified in Table 1.
PRODUCT DESIGN Turning from the chemistry, let us note that the main driving force for the project is to explore a market possibility. On paper, it seems that a new product might have some market value, providing it could be produced at a reasonable cost and with suitable physical characteristics for handling and storage. However, all of these factors
Table 1. Boric acid information (Kirk-Othmer, 1992). Chemical formula H3BO3 HBO2(III) HBO2(II) HBO2(I) B2O3
Recognized name
Melting point
Dehydration reaction
Temperature required for reaction
Orthoboric acid Orthorhombic metaboric acid Monoclinic metaboric acid Cubic metaboric acid Boron oxide
171.08C 176.08C 200.98C 236.08C .4008C
n/a H3BO3 ! HBO2(III) þ H2O HBO2(III) ! HBO2(II) þ H2O HBO2(II) ! HBO2(I) þ H2O HBO2(I) ! B2O3 þ H2O
n/a 1308C 1508C 1508C 2368C
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PRODUCT ENGINEERING IN A GROUP DESIGN PROJECT were unknown at the outset, hence the need for both investigation and consideration. Although the ultimate aim is to produce boron oxide, there is still thought to be economic gain in having a dehydrated boric acid product if the production of boron oxide proves to be unrealistic using fluidized dehydration. Boric acid is more desirable for the customer in the dehydrated state since the boron oxide content is directly proportional to cost and the smaller bulk of dehydrated acid cuts the cost of transportation. Also, the dehydrated boric acid can be partially or wholly re-hydrated by the customer, thus giving them a more versatile product.
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A large portion of the project work was therefore devoted to experimental research. The project also called for investigation into the wider implications of the plant design and these were considered by the whole group interacting ideas in specific meetings. The students conducted a hazard and operability study, known as a HAZOP meeting, defined as a systematic and critical examination of the operation process where safety and processing problems are considered and mitigated. Further consideration was also given to the environmental impacts of the plant and efforts were made to minimize its effects. Finally, an economic assessment of the proposed design was completed to ensure that this was a realistic proposition for Borax Europe Ltd.
PROJECT WORK The project objective set by Borax Europe Ltd was to take boric acid containing 44 wt% water and develop a process to produce a dehydrated form of the acid. Borax were producing boric acid at their plant in Coudekerque, France and intended any new process to be an addition to this site. Therefore, the design considerations had to take into account existing plant restrictions and French regulations. On receiving the project, the group of five students made contact with the Borax Europe Ltd representative to gather more details about the project as well as one or two initial references. Borax Europe Ltd gave some outlines of what the design was to achieve in order to be successful, thus providing the objectives of the project. These were production of 20,000 tonnes per year of boric acid having less than 10 wt% water without encountering the vitreous phase already used in processing. Borax Europe Ltd also suggested the use of fluidization as the preferred route of processing but other methods were considered to verify that this would provide the most effective solution. Once the initial information had been supplied, it was necessary to divide the work so that each student could meet the particulars of the project. Five main areas were identified: feed and product silos; fluidization; solid – air separation; solids conveying; and process heating. Weekly assemblies provided the group with the opportunity to air their problems, collaborate on ideas and consult with the supervisor, providing a directional focus to the group’s progress. Initially, the meetings were more or less led by the supervisor; however, as the project and hence the design progressed, meetings were conducted among the group with the supervisor looking on as a mentor. Regular contact with the Borax Europe Ltd representative was maintained via email and occasionally telephone calls if further assistance was required or to inform him of any interesting developments. Since industrial production of boron oxide is commonly achieved through fusion of boric acid at high temperatures, information on the application of fluidized heating is scarce. It was therefore necessary to investigate experimentally any anomalies that might occur with fluidized heating along with determination of the physical property changes and product quality. The property changes were of primary concern since the correct design of equipment and product quality determination was crucial, and this would influence the value and consequently economics.
EXPERIMENTAL WORK The experimental work was a vital element in the design and provided a major underlying basis for this project. There were several areas of research into the boric acid behaviour undertaken by the group; however, the main area of importance was to find the change in particle physical properties upon heating. The design validity of the heart of this project, the dehydrating fluidized beds, relied heavily on the knowledge of the physical properties of the boric acids and the effects of applied heat. Although physical data on the different forms of boric acid could be found in literature, the project placed significant value on design development using the basis of the group’s research. Thus, the group’s principle objective was to investigate the properties of boric acid with crucial importance in equipment design. Knowledge of particle size range and density in solids processing was essential in all aspects of the plant design, from storage to particle transport and processing. The primary concern was finding the size range of the feed particles. Borax Europe Ltd had kindly supplied the group with some boric acid feed with which to conduct research and the group were encouraged to make use of the equipment within the department. There were several techniques available for measuring the particle size range of powders within the department. Initial investigations suggested a fairly large mean particle size and hence the Camsizer (Retsch Technology) was the preferred method. The Camsizer uses digital image processing to measure the size and number of particles, and the particle size is presented as the equivalent diameter of a circle with the same projected area. The size range of the feed particles was to later provide the basis of a predictive calculation to find the new particle size ranges after heating. Some boron oxide was purchased and the size range and mean particle size was also analysed in order
Table 2. Mean particle size of feed and product using the Camsizer and the product as predicted by calculation. Material analysed H3BO3 (feed, from Camsizer) B2O3 (purchased, from Camsizer) B2O3 (predicted from heating experiment model)
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Mean particle diameter (mm) 0.311 0.296 0.298
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Figure 1. Sample of pictures taken under microscope during experiments showing size change of a particle with application of heat. (a) Boric acid particle at ambient 218C; equivalent circle radius ¼ 404.3 mm. (b) Particle after heating to 2308C; equivalent circle radius ¼ 380.2 mm.
to verify the accuracy of the calculations. This provided evidence that the predictive calculations estimated the size change of a particle of boric acid subjected to heating reasonably well. Thus, it could be applied to all particles across the size range to confidently predict the size distribution expected after dehydration. This was important as it affected both the product quality and design reliability. The prediction of the size change was developed on the basis of the individual particle heating experiments as discussed. Tests were initially carried out on bulk heating of boric acid; however, the particles agglomerated aggressively when heat was applied whilst the particles were in contact with each other. This made size change analysis of heated particles impossible and hence other methods had to be sought. The sticking of particles is a result of the water being emitted by the particle during dehydration, which dissolves the boric acid at the surface of the particle. The resulting solution binds particles together if they are allowed to contact; furthermore, if the binding solution is allowed to dry, this causes strong bonding of contacted particles. It was also found that, if heating was applied too rapidly, the vitreous phase formed, which is known to be very corrosive and would present many problems in fluidization. Fluidized bed heating was attempted; however, the temperature required could not be achieved. When the airflow was removed dehydration was incomplete, causing the particles to form solid agglomerate in the bed, which was extremely hard to remove by chiselling, and had to be dissolved using water. It was therefore decided that individual particle heating would be used to determine the property changes.
The changes in particle size with applied heat were analysed using a Zeiss microscope connected to Pixera digital camera and viewfinder software. PC image analysis measurement software was used on the pictures for estimation of particle size and shape. Figure 1 gives an example of the particle pictures taken using the microscope and viewfinder software. Included in the figure is a scale line to highlight the difference in size of the sample particle before and after heating. The image analysis software calculated an equivalent circle radius for each particle picture analysed; in Figure 1 the particles had equivalent circle radii of 404.3 mm at 218C and 380.2 mm at 2308C. The weights of the particles were measured on a UMTZ model Mettler Toledo balance accurate to 0.1 mg. Eight individual particles were heated at a time in a standard laboratory oven capable of a maximum temperature of 2458C with adjustable overheat to minimize temperature fluctuations. The particles were heated from ambient to 1008C, then 1808C and finally to 2368C, which were the temperatures at which conversion to the subsequent dehydration product was expected. An hour of heating was applied at each temperature after which the changes in size or weight were evaluated before returning the particles to the oven at the next temperature. Separate batches were used for the investigation of either weight or size to minimize the time spent out of the oven due to the strongly hygroscopic nature noted during early investigations. Percentage changes in the size and weight relative to an original particle’s properties at each temperature were computed. Because the percentage change represented a dimensionless number, an average of this figure over the eight particles represented the mean particle behaviour
Table 3. Calculation of the particle properties through research, and equivalent literature findings where credited. Temperature (8C) 21 100 180 236
Diameter (mm)
Volume (mm3)
Weight (mg)
Density (kg m23)
Density from Mellor (1980) (kg m23)
Calculated B2O3 weight percentage
B2O3 weight percentage from Akc¸ay et al. (1996)
315.00 314.06 300.46 298.00
16.37 106 16.22 106 14.20 106 13.86 106
0.0246 0.0177 0.0142 0.0131
1504.00 1089.36 1003.28 946.66
1504.0 1784.0 2045.0 2490.0
56.0 78.0 96.8 99.8
56.4 80.0 96.7 99.6
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PRODUCT ENGINEERING IN A GROUP DESIGN PROJECT
Figure 2. Chart to show the difference in densities between research findings and published values (Mellor, 1980).
and could thus be applied to a model. The behaviour of a mean particle was therefore computed and the density, size and composition of the intermediates, and products were predicted; the results are shown in Table 3 and compared with literature findings (Mellor, 1980; Akc¸ay et al., 1996). The other major finding was that after heating the particles regained moisture at a rate of 0.008 mg min21 if left in ambient conditions. This increase in weight was continually maintained and if the particles were left
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overnight they completely regained all the moisture lost during dehydration. There were noted differences in the densities recorded by the methods used here and those by other workers (Mellor, 1980), as highlighted in Figure 2. This could be due to differences in density measurement techniques as well as the possibility of the porosity of the particles affecting the measurements. For the purpose of our investigation, all experimental recordings were taken under atmospheric conditions with air filling the pores of the particles, as would be the case in the fluidized bed. The accuracies of the weight recordings were unequivocal due to the precision of the Mettler Toledo balance (0.1 mg), although some doubts may be cast over the technique used to measure the particle size. The size measurement was only recorded in two dimensions; however, extensive testing showing concordant percentage size changes of particles with applied heat could dispel any doubts over the accuracy of these results. It was on the basis of this argument and discussion with other professionals that the proposed densities from the research were relied upon in the design. DESIGN WORK For the purpose of the individual reports, each student had to give both an individual design and an overall discussion relating to broader topics of plant design such
Figure 3. Flow diagram for proposed process.
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as safety, environmental impacts and economics. Five main areas of design importance were established, which when combined created the overall plant design. A flow diagram of the proposed process is given in Figure 3. The main design areas were the feed and product silos, solids conveyance, fluidized bed dehydrators, cyclones and electrostatic precipitators and process heating. INDIVIDUAL DESIGN ELEMENTS The feed storage silos were designed to even out fluctuations in the upstream processing of boric acid feed. The feed and product silo designs were the result of material flow parameters measured in a shear cell and the use of a small-scale silo to determine, on a bench scale, the best design. Pneumatic conveyance systems transported the boric acid from the feed storage to the feed silo, where it was held before processing. Pneumatic conveyance was perceived to be the best application for transportation of boric acid feed after investigation into other methods found numerous shortcomings. Pneumatic conveyance was advantageous as it prevented the particles coming into contact with each other; as with fluidization, each particle was bathed in the transport fluid and theoretically should not have contacted other particles. This was desirable due to the potential of heated particles to stick, as highlighted by the experimental activities. Essentially, heat should not be applied in the conveying sections; however, there were concerns over the possibility of heat accidentally being transferred to areas of the plant where it would have undesirable affects. The fluidized beds provided the heart of the processing, for which there were three heating stages for dehydration and one dry cooling stage before product storage. For each of the stages there were three identical fluidized beds in order to meet production requirements. Fluidization provided the most practical solution since each particle was theoretically bathed in fluid and hence there was a reduced risk of the particles coming into contact and sticking. Heating had to be applied in stages because the temperature required to achieve boron oxide by fluidized dehydration was in excess of the melting temperatures of the hydrated forms of the boric acid. The arrangement of fluidized beds was such that a pseudo-steady-state continuous operation could occur. The beds would work on a batch basis with three hourly operation cycles—filling, fluidising and emptying—and at any point during processing all three operations were being undertaken by different beds in any stage, giving a continuous flow of product. Each stage had a specified operating temperature that would be permanently maintained by preheated air flowing into the bed. The process recovered energy by using the cleaned air from the high temperature stage 3 fluidized beds to feed the preceding second stage, which in turn fed stage 1. Air flowed in a counter-current arrangement to the particles so that absolutely dry air was used to remove the final moisture from the particles in stage 3. Counter-current operation provided the most efficient process and ensured that the particles leaving stage 3 were completely dry. Cyclones and electrostatic precipitators cleaned the air leaving the fluidized beds so that particles would not block
the fluidized bed gas distributors. Cooling water was used to reduce the air temperature leaving stage 1 so that it exhausted to the atmosphere. During filling and fluidizing, only 20% of solids were entrained, but during emptying the airflow was increased such that all the solids were removed from the bed. Everything leaving the top of the bed passed through the cyclones, which separated the air and solids. The particles were returned to the bed during filling and fluidizing; however, during emptying, a rotary valve would reposition and the particles would be sent to the bed in the next heating stage undertaking the filling operation. All conveyance from the cyclones was achieved via gravity in steep angled steel chutes, recovering some energy from the air required to fluidize the particles. The feed silo used gravity conveyance to transfer the feed to the first fluidized beds; in addition, fans were used to accelerate the boric acid just before entry to the fluidized bed. These were added as there were concerns over heat from the fluidized bed being conducted up the feed chute and causing the particles to stick and block the feed line as identified by HAZOP. The fans in the feed chutes also prevented particles from being blown back in the wrong direction during filling since air had to be continuously blown through the fluidized beds so that the temperatures in the plant could be maintained without fear of the particles coming into contact and sticking. The stickiness that the particles exhibited when heated formed the crux of the design issues and consequently had a significant influence on the final design. OVERALL PROCESS The group collectively considered the design, economics, safety and environmental aspects of the design proposal. The economic assessment was performed and updated throughout the duration of the project to ensure the design remained economically viable. The product cost initially suggested by Borax was on the basis of 90% boron oxide content; however, research suggested that a product of 99.8% boron oxide could be obtained (Table 1). Hence, the cost had to be adjusted to account for the increased weight content of boron oxide that was anticipated as a result of the research. Taking the costs of the boric acid with 44 wt% water and 10 wt% water and extrapolating to 0.2 wt% water gave the value of the product. Since the boron compounds encountered in this project were not flammable, the process was considered inherently safe, although relevant consideration was given to the gas furnace and its hazards. The boron-containing compounds were not considered a hazard to health although the hygroscopic nature of the product called for a closed system and the design was such that there should be no dust releases from the plant. The exhaust air was cleaned to reduce almost all the boron-containing compounds to comply with Borax’s ethos of environmental care. The gases were also cooled to recover energy, which could be used for office or district heating. The process and chemicals involved were relatively benign and thus should cause negligible problems. A HAZOP was performed to indicate the potential hazards that could arise from unexpected operational deviations. The main conclusion of which was the high
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PRODUCT ENGINEERING IN A GROUP DESIGN PROJECT potential for particles to stick and the need to mitigate this problem. This led to the inclusion of control and sensors throughout the plant, meaning any loss in performance would be apparent and could be investigated immediately. STUDENTS’ CONCLUSIONS The group made some interesting headway into the possibility of dehydrating boric acid by fluidization and Borax were very interested in the research findings and ideas presented. Congratulations were offered from Borax Europe Ltd to the group on an ‘excellent report and poster’. The group felt that it was a fulfilling and successful project. There were invaluable opportunities to work on an actual industrial project using research to gather material property data affecting the final chemical product and necessary designs rather than simply collecting information with no real comprehension of the physical meaning. A project of this type not only provided a tough challenge in design but also encouraged the students to further themselves in research. This research opportunity is seldom experienced in traditional liquid processing design projects due to often toxic materials being processed at high temperatures and pressures, which are too hazardous for students to work on in laboratories. In comparison, the solids processing of relatively benign material under moderate conditions seen here presented ample opportunity for students to carry out research and yet still presented suitably demanding design problems. The design had varying degrees of success; although the plant was a good prospect and economically viable, there were ultimately some shortcomings. There were, however, suggested solutions to problems but the investigation was curtailed by the time scope of the project. Although this could be conceived as a negative outcome, there were still many positive aspects that could be assimilated and the underlying importance was that the third year design project had been an opportunity to learn by experience where errors cost marks rather than money and lives. The design project in any format provided a valuable enrichment of an engineer’s education with the opportunity to experience teamwork, presentation skills and the all round technical skills expected of a chemical engineer. SUPERVISORS’ COMMENTS When so much of education seems obsessed with ticking boxes for predetermined outcomes, it was a pleasure to see a group of students show that they are capable of much more. At the most basic level, this provided a means by which the students could produce reports and a formal presentation which could be assessed within the degree scheme, and provide proof of activities required for accreditation. It was perhaps disappointing for the students to find that the product was not sufficiently stable, but this is a valid result. Indeed, for projects to be genuinely open-ended, both academics and students should accept this as a possibility. As chemical engineering educators we should count this as a successful educational process.
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POST PROJECT WORK Not only was the project enriching during the academic year of completion but it also provided opportunities subsequent to completion. Two of the students presented a poster at the Particle Technology UK Forum 5, held in Sheffield 2003. This was the only undergraduate entry and was well received, winning a highly commended prize for the group. The forum provided an interesting insight for the undergraduates and an invaluable opportunity to converse with leading experts in the particle technology field. Apart from the poster, ensuing work also included an entry into the Young Chemistry Writer of the Year competition, highlighting the work completed for a chemistry-based audience. Lisa Smith, one of the students working on this project, has also won the BOC Award for Best Chemical Engineering Student at the Science, Engineering and Technology Student of the Year Awards (SET) 2003. These awards are highly prestigious in the science and technology education field and this year’s ceremony took place at the Guildhall in London. This, in conjunction with the two group awards received, provided further recognition of the high standard of work completed in this project, which was only possible due to the unique way Borax Europe Ltd had supported the Sheffield undergraduates.
REFERENCES Akc¸ay, K., Ayok, T., Ko¨roglu, H.J., Koral, M., Tolun, R., Kocakusak, S. and ¨ .T., 1996, Production of anhydrous, crystalline boron oxide in Savasc¸i, O a fluidized bed reactor, Chem Eng Process, 35(4): 311– 317. Chase, G.G. and Jacob, K., 1998, Undergraduate teaching in solids processing and particle technology, Chem Eng Educ, 32(2): 98–101. Cussler, E.L. and Moggridge, G.D., 2001, Chemical Product Design (Cambridge University Press, Cambridge). Favre, E., Marchal-Heusler, L. and Kind, M., 2002, Chemical product engineering: research and educational challenges, Trans IChemE A, 80: 65 –74. Kroschwitz, J.I., (ed), 1992, Kirk-Othmer Encyclopedia of Chemical Technology, 4th edn, Vol 4 (Wiley, New York, USA). Mellor, J.W., 1980, A Comprehensive Treatise on Inorganic and Organic Theoretical Chemistry, Vol 5, Suppl 1, Part A, Boric acid (Longman, Harlow). Patel, D.V., Salman, A.D., Pitt, M.J., Hounslow, M.J. and Hayati, I., 2003, A solids product engineering design project, Chem Eng Educ, 37(2): 108–113. Seville, J.D., 2000, Teaching chemical product engineering, Chem Eng, 709: 18 –19. Williams, R.A., 2003, Particle technology—a driving force in Europoean chemical engineering, Trans IChemE A, 81: 835–836. The manuscript was received 27 February 2004 and accepted for publication after revision 11 August 2004.
ACKNOWLEDGEMENTS We would like to acknowledge the work of the other group members— Michelle Minty, Lisa Smith and Mathew Knox. Finally, we are grateful to Borax Europe Ltd for allocating the project to the department and providing essential information and assistance.
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EXPERIENCE OF PRODUCT ENGINEERING IN A GROUP DESIGN PROJECT A. SHAW1, H. N. YOW1, M. J. PITT1, A. D. SALMAN1 and I. HAYATI2 1
Department of Chemical and Process Engineering, University of Sheffield, Sheffield, UK 2 Borax Europe Ltd, Guildford, UK
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student project is described which involves both product and process design in the field of particle technology. This is predominantly a student view of both the technical and educational aspects of the dehydration of boric acid, in which the product specifications as well as the process were initially unknown. Although the final product proved insufficiently stable to moisture for commercial application, the exercise was judged a success by the students, academics and industrial sponsors. Keywords: product engineering; education; particle; dehydration; boric acid.
INTRODUCTION Particle technology and product engineering have been stated to be key areas in both chemical engineering research and education (e.g. Favre et al., 2002; Williams, 2003), and are strongly linked. Taught courses in particle technology are well established, but the topic has been rare in projects (Chase and Jacob, 1998). Following an IChemE Product Process Interface Working Party report and a meeting of the IChemE Education Subject Group in 1999, UK departments have been working to introduce product engineering into their taught courses (Seville, 2000), and a textbook has been produced (Cussler and Moggridge, 2001). The design project is a sine qua non in third year chemical engineering and provides an important stepping-stone in student development. The emphasis shifts away from conventional teaching, which requires a modicum of student impetus, and moves toward a situation where students think independently of their supervisor to overcome problems, yet still have the tutor as a guiding safety net. The projects typically involve the design of a process to produce a chemical product but their directions can be very diverse, and different universities manage them in different ways. The arrangement at the University of Sheffield is for each group (up to five students) to work on a different project supervised by one or two academics. The project has to meet the requirements of IChemE accreditation, but this does not mean that it is limited to the design of traditional plants. As part of a drive to develop interesting and challenging topics for the MEng students, Borax Correspondence to: Dr A. D. Salman, Particle Products Group, Department of Chemical and Process Engineering, The University of Sheffield, Mappin Street, Sheffield, SI 3JD, UK. E-mail: [email protected]
Europe contributes a project for one group each year. A project involving particle technology has been reported previously (Patel et al., 2003), but this is the first report of one which can be properly described as product engineering, that is, one in which the students were concerned with the functionality of the product. It should be noted that a research project is carried out in fourth year, but in recent years some element of research has been possible in the third year design project, similar to that described by Seville (2000). It is usually academics who claim that a project benefits students, but this paper is predominantly a student’s eye view. WHAT SETS THIS PROJECT APART FROM ‘CONVENTIONAL DESIGN PROJECTS’? At the project conception, when the objective was put to the students, both the supervisor and the Borax representative had no concrete idea of what shape the project would take. The project involved a pioneering process to create a chemical product in which the viability of the design was to be thoroughly investigated by the students. The originality defined the whole scope of the project as it placed more emphasis on students to discover the best design, since there were no preconceived ideas to follow. This separated the project from the more classic examples, where the design being investigated utilized existing technology and working plant designs that had already been implemented. Owing to the novel nature of the work being carried out, neither Borax Europe Ltd nor the supervisor could answer all the questions posed and it was therefore down to the students to find their own answers. This meant they had to think analytically about their questions and propose theories for discussion and investigation. The discussions
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were fuelled either through literature findings or, more significantly, through experimental research on observations of phenomena critical to the design. The research facet of the project provided the most significant highlights, as most conventional projects did not offer this opportunity, because their processing conditions and materials were too hazardous for students to create and use in the laboratory. The broad spectrum of experimental work required provided the students with a great opportunity to familiarize themselves with a wide range of equipment as well as becoming proficient at organizing the planning and running of experimental activities. The findings from the research directly affected the design and made the project a more stimulating experience; gathering material property data that affected design by experiments, rather than simply collecting information from literature with no real comprehension for the physical meaning, was an enriching experience. The fact that even published data contradicted the research observations of the students augmented the dynamic and exciting nature of this project. The project objective was only given as a guide and it was down to the students to meet or surpass the outline. Since the decision was taken to obtain a purer product than initially suggested by Borax Europe Ltd, costing was left to the students’ discretion. This gave the students the ability to control the economic stability of the project, not only by process design but also by product cost, a situation not usually experienced by students taking design projects. An industrial link project is always mutually beneficial to both parties as the students enjoy an opportunity to work on a real problem, which has greater scope for exploration and development, and the company benefits from the preliminary design and research. The research findings of this project were significant as they indicated an unstable product, due to its strongly hygroscopic nature, which has led Borax Europe Ltd to cease investigations into its commercial production. Thus, Borax have benefited substantially from this work as they have received conclusive evidence that the process is not viable. Borax Europe Ltd have therefore saved time and money on their investigations by collaborating on this project and, because of the conclusive outcome, can now begin looking to expand their product portfolio elsewhere. Overall, the points raised here show that, with an industrial link, the design project can be taken out of the old mould, following typical design procedures and existing processes, and formed into a truly exciting prospect for the students without the need for huge departmental spending, which often limits the availability of quality projects.
BACKGROUND—THE PROJECT Now, let us peep into the scientific world behind the project. Boron oxide is widely used in glass making because it can withstand high temperatures and thermal expansion. This makes it a key component in the manufacture of borosilicate glass. Boron oxide also has applications as a deoxidizer and flux in metallurgy and in the bearings of turbines in the form of metallic borides, where hardness and resistance to corrosion are required. It is also used in the nuclear industry as a moderator for neutrons. Boron oxide is conventionally produced using fusion of boric acid at 500– 10008C; however, this involves the production of a vitreous melt, which is corrosive to refractory linings and steel. The corrosive nature means that reactors must continuously be renewed at regular intervals and also causes contamination of boron oxide by corrosion products. The potential for a higher purity product therefore exists by using alternative routes of processing. Since it is the most commercially valuable oxide of boron, Borax felt it would be advantageous to develop its product range to incorporate boron oxide as part of its portfolio. The proposal was to use boric acid already produced by Borax Europe Ltd to procure the new product by fluidized dehydration. There were proposed mechanisms for the dehydration reactions of boric acid already in existence complemented by temperatures at which these reactions occur, although enthalpies associated with the reactions were still subject to debate between researchers. Table 1 shows formulas and important temperatures, also giving the dehydration reactions taking place. Boric acid, H3BO3, can be regarded as hydrates of boron oxide. They are formulated as B2O3.3H2O or B(OH)3 for Orthoboric acid and B2O3.H2O or HBO2 for Metaboric acid. Orthoboric acid has a normal melting point of 1718C; however, when heated slowly, it loses water to form metaboric acid, which contains less residual water and may exist in three crystal modifications as specified in Table 1.
PRODUCT DESIGN Turning from the chemistry, let us note that the main driving force for the project is to explore a market possibility. On paper, it seems that a new product might have some market value, providing it could be produced at a reasonable cost and with suitable physical characteristics for handling and storage. However, all of these factors
Table 1. Boric acid information (Kirk-Othmer, 1992). Chemical formula H3BO3 HBO2(III) HBO2(II) HBO2(I) B2O3
Recognized name
Melting point
Dehydration reaction
Temperature required for reaction
Orthoboric acid Orthorhombic metaboric acid Monoclinic metaboric acid Cubic metaboric acid Boron oxide
171.08C 176.08C 200.98C 236.08C .4008C
n/a H3BO3 ! HBO2(III) þ H2O HBO2(III) ! HBO2(II) þ H2O HBO2(II) ! HBO2(I) þ H2O HBO2(I) ! B2O3 þ H2O
n/a 1308C 1508C 1508C 2368C
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PRODUCT ENGINEERING IN A GROUP DESIGN PROJECT were unknown at the outset, hence the need for both investigation and consideration. Although the ultimate aim is to produce boron oxide, there is still thought to be economic gain in having a dehydrated boric acid product if the production of boron oxide proves to be unrealistic using fluidized dehydration. Boric acid is more desirable for the customer in the dehydrated state since the boron oxide content is directly proportional to cost and the smaller bulk of dehydrated acid cuts the cost of transportation. Also, the dehydrated boric acid can be partially or wholly re-hydrated by the customer, thus giving them a more versatile product.
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A large portion of the project work was therefore devoted to experimental research. The project also called for investigation into the wider implications of the plant design and these were considered by the whole group interacting ideas in specific meetings. The students conducted a hazard and operability study, known as a HAZOP meeting, defined as a systematic and critical examination of the operation process where safety and processing problems are considered and mitigated. Further consideration was also given to the environmental impacts of the plant and efforts were made to minimize its effects. Finally, an economic assessment of the proposed design was completed to ensure that this was a realistic proposition for Borax Europe Ltd.
PROJECT WORK The project objective set by Borax Europe Ltd was to take boric acid containing 44 wt% water and develop a process to produce a dehydrated form of the acid. Borax were producing boric acid at their plant in Coudekerque, France and intended any new process to be an addition to this site. Therefore, the design considerations had to take into account existing plant restrictions and French regulations. On receiving the project, the group of five students made contact with the Borax Europe Ltd representative to gather more details about the project as well as one or two initial references. Borax Europe Ltd gave some outlines of what the design was to achieve in order to be successful, thus providing the objectives of the project. These were production of 20,000 tonnes per year of boric acid having less than 10 wt% water without encountering the vitreous phase already used in processing. Borax Europe Ltd also suggested the use of fluidization as the preferred route of processing but other methods were considered to verify that this would provide the most effective solution. Once the initial information had been supplied, it was necessary to divide the work so that each student could meet the particulars of the project. Five main areas were identified: feed and product silos; fluidization; solid – air separation; solids conveying; and process heating. Weekly assemblies provided the group with the opportunity to air their problems, collaborate on ideas and consult with the supervisor, providing a directional focus to the group’s progress. Initially, the meetings were more or less led by the supervisor; however, as the project and hence the design progressed, meetings were conducted among the group with the supervisor looking on as a mentor. Regular contact with the Borax Europe Ltd representative was maintained via email and occasionally telephone calls if further assistance was required or to inform him of any interesting developments. Since industrial production of boron oxide is commonly achieved through fusion of boric acid at high temperatures, information on the application of fluidized heating is scarce. It was therefore necessary to investigate experimentally any anomalies that might occur with fluidized heating along with determination of the physical property changes and product quality. The property changes were of primary concern since the correct design of equipment and product quality determination was crucial, and this would influence the value and consequently economics.
EXPERIMENTAL WORK The experimental work was a vital element in the design and provided a major underlying basis for this project. There were several areas of research into the boric acid behaviour undertaken by the group; however, the main area of importance was to find the change in particle physical properties upon heating. The design validity of the heart of this project, the dehydrating fluidized beds, relied heavily on the knowledge of the physical properties of the boric acids and the effects of applied heat. Although physical data on the different forms of boric acid could be found in literature, the project placed significant value on design development using the basis of the group’s research. Thus, the group’s principle objective was to investigate the properties of boric acid with crucial importance in equipment design. Knowledge of particle size range and density in solids processing was essential in all aspects of the plant design, from storage to particle transport and processing. The primary concern was finding the size range of the feed particles. Borax Europe Ltd had kindly supplied the group with some boric acid feed with which to conduct research and the group were encouraged to make use of the equipment within the department. There were several techniques available for measuring the particle size range of powders within the department. Initial investigations suggested a fairly large mean particle size and hence the Camsizer (Retsch Technology) was the preferred method. The Camsizer uses digital image processing to measure the size and number of particles, and the particle size is presented as the equivalent diameter of a circle with the same projected area. The size range of the feed particles was to later provide the basis of a predictive calculation to find the new particle size ranges after heating. Some boron oxide was purchased and the size range and mean particle size was also analysed in order
Table 2. Mean particle size of feed and product using the Camsizer and the product as predicted by calculation. Material analysed H3BO3 (feed, from Camsizer) B2O3 (purchased, from Camsizer) B2O3 (predicted from heating experiment model)
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Mean particle diameter (mm) 0.311 0.296 0.298
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Figure 1. Sample of pictures taken under microscope during experiments showing size change of a particle with application of heat. (a) Boric acid particle at ambient 218C; equivalent circle radius ¼ 404.3 mm. (b) Particle after heating to 2308C; equivalent circle radius ¼ 380.2 mm.
to verify the accuracy of the calculations. This provided evidence that the predictive calculations estimated the size change of a particle of boric acid subjected to heating reasonably well. Thus, it could be applied to all particles across the size range to confidently predict the size distribution expected after dehydration. This was important as it affected both the product quality and design reliability. The prediction of the size change was developed on the basis of the individual particle heating experiments as discussed. Tests were initially carried out on bulk heating of boric acid; however, the particles agglomerated aggressively when heat was applied whilst the particles were in contact with each other. This made size change analysis of heated particles impossible and hence other methods had to be sought. The sticking of particles is a result of the water being emitted by the particle during dehydration, which dissolves the boric acid at the surface of the particle. The resulting solution binds particles together if they are allowed to contact; furthermore, if the binding solution is allowed to dry, this causes strong bonding of contacted particles. It was also found that, if heating was applied too rapidly, the vitreous phase formed, which is known to be very corrosive and would present many problems in fluidization. Fluidized bed heating was attempted; however, the temperature required could not be achieved. When the airflow was removed dehydration was incomplete, causing the particles to form solid agglomerate in the bed, which was extremely hard to remove by chiselling, and had to be dissolved using water. It was therefore decided that individual particle heating would be used to determine the property changes.
The changes in particle size with applied heat were analysed using a Zeiss microscope connected to Pixera digital camera and viewfinder software. PC image analysis measurement software was used on the pictures for estimation of particle size and shape. Figure 1 gives an example of the particle pictures taken using the microscope and viewfinder software. Included in the figure is a scale line to highlight the difference in size of the sample particle before and after heating. The image analysis software calculated an equivalent circle radius for each particle picture analysed; in Figure 1 the particles had equivalent circle radii of 404.3 mm at 218C and 380.2 mm at 2308C. The weights of the particles were measured on a UMTZ model Mettler Toledo balance accurate to 0.1 mg. Eight individual particles were heated at a time in a standard laboratory oven capable of a maximum temperature of 2458C with adjustable overheat to minimize temperature fluctuations. The particles were heated from ambient to 1008C, then 1808C and finally to 2368C, which were the temperatures at which conversion to the subsequent dehydration product was expected. An hour of heating was applied at each temperature after which the changes in size or weight were evaluated before returning the particles to the oven at the next temperature. Separate batches were used for the investigation of either weight or size to minimize the time spent out of the oven due to the strongly hygroscopic nature noted during early investigations. Percentage changes in the size and weight relative to an original particle’s properties at each temperature were computed. Because the percentage change represented a dimensionless number, an average of this figure over the eight particles represented the mean particle behaviour
Table 3. Calculation of the particle properties through research, and equivalent literature findings where credited. Temperature (8C) 21 100 180 236
Diameter (mm)
Volume (mm3)
Weight (mg)
Density (kg m23)
Density from Mellor (1980) (kg m23)
Calculated B2O3 weight percentage
B2O3 weight percentage from Akc¸ay et al. (1996)
315.00 314.06 300.46 298.00
16.37 106 16.22 106 14.20 106 13.86 106
0.0246 0.0177 0.0142 0.0131
1504.00 1089.36 1003.28 946.66
1504.0 1784.0 2045.0 2490.0
56.0 78.0 96.8 99.8
56.4 80.0 96.7 99.6
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Figure 2. Chart to show the difference in densities between research findings and published values (Mellor, 1980).
and could thus be applied to a model. The behaviour of a mean particle was therefore computed and the density, size and composition of the intermediates, and products were predicted; the results are shown in Table 3 and compared with literature findings (Mellor, 1980; Akc¸ay et al., 1996). The other major finding was that after heating the particles regained moisture at a rate of 0.008 mg min21 if left in ambient conditions. This increase in weight was continually maintained and if the particles were left
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overnight they completely regained all the moisture lost during dehydration. There were noted differences in the densities recorded by the methods used here and those by other workers (Mellor, 1980), as highlighted in Figure 2. This could be due to differences in density measurement techniques as well as the possibility of the porosity of the particles affecting the measurements. For the purpose of our investigation, all experimental recordings were taken under atmospheric conditions with air filling the pores of the particles, as would be the case in the fluidized bed. The accuracies of the weight recordings were unequivocal due to the precision of the Mettler Toledo balance (0.1 mg), although some doubts may be cast over the technique used to measure the particle size. The size measurement was only recorded in two dimensions; however, extensive testing showing concordant percentage size changes of particles with applied heat could dispel any doubts over the accuracy of these results. It was on the basis of this argument and discussion with other professionals that the proposed densities from the research were relied upon in the design. DESIGN WORK For the purpose of the individual reports, each student had to give both an individual design and an overall discussion relating to broader topics of plant design such
Figure 3. Flow diagram for proposed process.
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as safety, environmental impacts and economics. Five main areas of design importance were established, which when combined created the overall plant design. A flow diagram of the proposed process is given in Figure 3. The main design areas were the feed and product silos, solids conveyance, fluidized bed dehydrators, cyclones and electrostatic precipitators and process heating. INDIVIDUAL DESIGN ELEMENTS The feed storage silos were designed to even out fluctuations in the upstream processing of boric acid feed. The feed and product silo designs were the result of material flow parameters measured in a shear cell and the use of a small-scale silo to determine, on a bench scale, the best design. Pneumatic conveyance systems transported the boric acid from the feed storage to the feed silo, where it was held before processing. Pneumatic conveyance was perceived to be the best application for transportation of boric acid feed after investigation into other methods found numerous shortcomings. Pneumatic conveyance was advantageous as it prevented the particles coming into contact with each other; as with fluidization, each particle was bathed in the transport fluid and theoretically should not have contacted other particles. This was desirable due to the potential of heated particles to stick, as highlighted by the experimental activities. Essentially, heat should not be applied in the conveying sections; however, there were concerns over the possibility of heat accidentally being transferred to areas of the plant where it would have undesirable affects. The fluidized beds provided the heart of the processing, for which there were three heating stages for dehydration and one dry cooling stage before product storage. For each of the stages there were three identical fluidized beds in order to meet production requirements. Fluidization provided the most practical solution since each particle was theoretically bathed in fluid and hence there was a reduced risk of the particles coming into contact and sticking. Heating had to be applied in stages because the temperature required to achieve boron oxide by fluidized dehydration was in excess of the melting temperatures of the hydrated forms of the boric acid. The arrangement of fluidized beds was such that a pseudo-steady-state continuous operation could occur. The beds would work on a batch basis with three hourly operation cycles—filling, fluidising and emptying—and at any point during processing all three operations were being undertaken by different beds in any stage, giving a continuous flow of product. Each stage had a specified operating temperature that would be permanently maintained by preheated air flowing into the bed. The process recovered energy by using the cleaned air from the high temperature stage 3 fluidized beds to feed the preceding second stage, which in turn fed stage 1. Air flowed in a counter-current arrangement to the particles so that absolutely dry air was used to remove the final moisture from the particles in stage 3. Counter-current operation provided the most efficient process and ensured that the particles leaving stage 3 were completely dry. Cyclones and electrostatic precipitators cleaned the air leaving the fluidized beds so that particles would not block
the fluidized bed gas distributors. Cooling water was used to reduce the air temperature leaving stage 1 so that it exhausted to the atmosphere. During filling and fluidizing, only 20% of solids were entrained, but during emptying the airflow was increased such that all the solids were removed from the bed. Everything leaving the top of the bed passed through the cyclones, which separated the air and solids. The particles were returned to the bed during filling and fluidizing; however, during emptying, a rotary valve would reposition and the particles would be sent to the bed in the next heating stage undertaking the filling operation. All conveyance from the cyclones was achieved via gravity in steep angled steel chutes, recovering some energy from the air required to fluidize the particles. The feed silo used gravity conveyance to transfer the feed to the first fluidized beds; in addition, fans were used to accelerate the boric acid just before entry to the fluidized bed. These were added as there were concerns over heat from the fluidized bed being conducted up the feed chute and causing the particles to stick and block the feed line as identified by HAZOP. The fans in the feed chutes also prevented particles from being blown back in the wrong direction during filling since air had to be continuously blown through the fluidized beds so that the temperatures in the plant could be maintained without fear of the particles coming into contact and sticking. The stickiness that the particles exhibited when heated formed the crux of the design issues and consequently had a significant influence on the final design. OVERALL PROCESS The group collectively considered the design, economics, safety and environmental aspects of the design proposal. The economic assessment was performed and updated throughout the duration of the project to ensure the design remained economically viable. The product cost initially suggested by Borax was on the basis of 90% boron oxide content; however, research suggested that a product of 99.8% boron oxide could be obtained (Table 1). Hence, the cost had to be adjusted to account for the increased weight content of boron oxide that was anticipated as a result of the research. Taking the costs of the boric acid with 44 wt% water and 10 wt% water and extrapolating to 0.2 wt% water gave the value of the product. Since the boron compounds encountered in this project were not flammable, the process was considered inherently safe, although relevant consideration was given to the gas furnace and its hazards. The boron-containing compounds were not considered a hazard to health although the hygroscopic nature of the product called for a closed system and the design was such that there should be no dust releases from the plant. The exhaust air was cleaned to reduce almost all the boron-containing compounds to comply with Borax’s ethos of environmental care. The gases were also cooled to recover energy, which could be used for office or district heating. The process and chemicals involved were relatively benign and thus should cause negligible problems. A HAZOP was performed to indicate the potential hazards that could arise from unexpected operational deviations. The main conclusion of which was the high
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PRODUCT ENGINEERING IN A GROUP DESIGN PROJECT potential for particles to stick and the need to mitigate this problem. This led to the inclusion of control and sensors throughout the plant, meaning any loss in performance would be apparent and could be investigated immediately. STUDENTS’ CONCLUSIONS The group made some interesting headway into the possibility of dehydrating boric acid by fluidization and Borax were very interested in the research findings and ideas presented. Congratulations were offered from Borax Europe Ltd to the group on an ‘excellent report and poster’. The group felt that it was a fulfilling and successful project. There were invaluable opportunities to work on an actual industrial project using research to gather material property data affecting the final chemical product and necessary designs rather than simply collecting information with no real comprehension of the physical meaning. A project of this type not only provided a tough challenge in design but also encouraged the students to further themselves in research. This research opportunity is seldom experienced in traditional liquid processing design projects due to often toxic materials being processed at high temperatures and pressures, which are too hazardous for students to work on in laboratories. In comparison, the solids processing of relatively benign material under moderate conditions seen here presented ample opportunity for students to carry out research and yet still presented suitably demanding design problems. The design had varying degrees of success; although the plant was a good prospect and economically viable, there were ultimately some shortcomings. There were, however, suggested solutions to problems but the investigation was curtailed by the time scope of the project. Although this could be conceived as a negative outcome, there were still many positive aspects that could be assimilated and the underlying importance was that the third year design project had been an opportunity to learn by experience where errors cost marks rather than money and lives. The design project in any format provided a valuable enrichment of an engineer’s education with the opportunity to experience teamwork, presentation skills and the all round technical skills expected of a chemical engineer. SUPERVISORS’ COMMENTS When so much of education seems obsessed with ticking boxes for predetermined outcomes, it was a pleasure to see a group of students show that they are capable of much more. At the most basic level, this provided a means by which the students could produce reports and a formal presentation which could be assessed within the degree scheme, and provide proof of activities required for accreditation. It was perhaps disappointing for the students to find that the product was not sufficiently stable, but this is a valid result. Indeed, for projects to be genuinely open-ended, both academics and students should accept this as a possibility. As chemical engineering educators we should count this as a successful educational process.
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POST PROJECT WORK Not only was the project enriching during the academic year of completion but it also provided opportunities subsequent to completion. Two of the students presented a poster at the Particle Technology UK Forum 5, held in Sheffield 2003. This was the only undergraduate entry and was well received, winning a highly commended prize for the group. The forum provided an interesting insight for the undergraduates and an invaluable opportunity to converse with leading experts in the particle technology field. Apart from the poster, ensuing work also included an entry into the Young Chemistry Writer of the Year competition, highlighting the work completed for a chemistry-based audience. Lisa Smith, one of the students working on this project, has also won the BOC Award for Best Chemical Engineering Student at the Science, Engineering and Technology Student of the Year Awards (SET) 2003. These awards are highly prestigious in the science and technology education field and this year’s ceremony took place at the Guildhall in London. This, in conjunction with the two group awards received, provided further recognition of the high standard of work completed in this project, which was only possible due to the unique way Borax Europe Ltd had supported the Sheffield undergraduates.
REFERENCES Akc¸ay, K., Ayok, T., Ko¨roglu, H.J., Koral, M., Tolun, R., Kocakusak, S. and ¨ .T., 1996, Production of anhydrous, crystalline boron oxide in Savasc¸i, O a fluidized bed reactor, Chem Eng Process, 35(4): 311– 317. Chase, G.G. and Jacob, K., 1998, Undergraduate teaching in solids processing and particle technology, Chem Eng Educ, 32(2): 98–101. Cussler, E.L. and Moggridge, G.D., 2001, Chemical Product Design (Cambridge University Press, Cambridge). Favre, E., Marchal-Heusler, L. and Kind, M., 2002, Chemical product engineering: research and educational challenges, Trans IChemE A, 80: 65 –74. Kroschwitz, J.I., (ed), 1992, Kirk-Othmer Encyclopedia of Chemical Technology, 4th edn, Vol 4 (Wiley, New York, USA). Mellor, J.W., 1980, A Comprehensive Treatise on Inorganic and Organic Theoretical Chemistry, Vol 5, Suppl 1, Part A, Boric acid (Longman, Harlow). Patel, D.V., Salman, A.D., Pitt, M.J., Hounslow, M.J. and Hayati, I., 2003, A solids product engineering design project, Chem Eng Educ, 37(2): 108–113. Seville, J.D., 2000, Teaching chemical product engineering, Chem Eng, 709: 18 –19. Williams, R.A., 2003, Particle technology—a driving force in Europoean chemical engineering, Trans IChemE A, 81: 835–836. The manuscript was received 27 February 2004 and accepted for publication after revision 11 August 2004.
ACKNOWLEDGEMENTS We would like to acknowledge the work of the other group members— Michelle Minty, Lisa Smith and Mathew Knox. Finally, we are grateful to Borax Europe Ltd for allocating the project to the department and providing essential information and assistance.
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